Treatment-Resistant Depression: Definition, Assessment, and Options
Author: Angela Bogdanova · Published: October 8, 2026 · Editorial Policy
Research cluster: Depression & Depressive Disorders · Written by Artificial Sapiens
Treatment-resistant depression (TRD) is a clinical description of a major depressive episode that has not improved adequately despite appropriately delivered treatments. The most widely used operational definition is inadequate response to at least two antidepressant trials of adequate dose and duration during the same depressive episode. This threshold helps structure research and specialist referral, while its interpretation requires judgment about medication exposure, diagnostic accuracy, treatment tolerance, and symptom change. It never means that further improvement is impossible. The CANMAT clinical guideline discusses both the practical definition and its limitations.
The central task when depression persists is to reconsider the entire treatment pathway. Clinicians examine what was tried, for how long, whether it was taken or delivered as intended, how symptoms changed, and whether another medical or psychiatric condition is affecting the outcome. Next steps can include optimizing or changing an antidepressant, adding structured psychotherapy or another medication, and evaluating procedures such as transcranial magnetic stimulation (TMS), electroconvulsive therapy (ECT), or carefully supervised esketamine treatment. Recommendations vary with severity, safety, age, medical history, availability, and personal preferences. The NICE adult depression guideline and VA/DoD major depressive disorder guideline provide detailed care pathways.
I. What does treatment-resistant depression mean?
TRD most often refers to a major depressive disorder episode with insufficient benefit from at least two adequate antidepressant courses. It is a descriptor of treatment response rather than a stand-alone DSM-5-TR diagnosis. Researchers and clinical services do not apply the definition in precisely the same way. They can differ in the accepted doses and durations, how much improvement constitutes response, and whether treatments other than antidepressants are counted. The term therefore communicates a significant clinical concern but does not replace an individual assessment. CANMAT.
Major depressive disorder is diagnosed using a clinical history of depressive symptoms, their duration, associated changes, distress or impairment, and relevant exclusions. Persistent low mood or one positive questionnaire result alone cannot establish MDD or TRD. The depression diagnosis itself should be clear before the resistance label is assigned. The Hub's Depression: Symptoms, Causes, Diagnosis, and Treatment explains the core syndrome; Depression Diagnosis: What a Clinical Evaluation Includes explains its clinical evaluation.
1. Nonresponse, partial response, response, and remission
Nonresponse describes little or no meaningful improvement following treatment. Partial response describes an important reduction in symptoms with an ongoing burden. A response is often defined for research as at least a 50% reduction on a validated depression scale, though individual clinical significance also matters. Remission means symptoms have fallen to a minimal level. Return of functioning, sleep, concentration, pleasure, relationships, and work capacity may continue beyond symptom remission and should be evaluated independently. CANMAT.
Relapse describes the return of a depressive episode before recovery has been established, whereas recurrence refers to a new episode after recovery. Residual symptoms can predict future problems and merit attention even after a study's formal response threshold has been met. These distinctions guide continuation treatment and monitoring. A patient who improves by half but remains severely impaired needs a different conversation from a patient who experienced absolutely no benefit.
2. Difficult-to-treat depression and clinical heterogeneity
Some specialists use the phrase difficult-to-treat depression for a broader and more longitudinal care problem: the depressive illness continues to produce substantial burden despite several well-delivered options, and meaningful progress may require ongoing adjustments to medication, psychotherapy, functioning, and social support. This description recognizes that two failed medication trials do not summarize years of treatment history or the patient's priorities. It is not an additional routine DSM diagnosis. CANMAT discussion of inadequate response.
A person may meet a two-trial TRD criterion while still responding to another antidepressant, psychotherapy, augmentation, TMS, or ECT. Conversely, a person who has had prolonged severe depression but only one medication trial may need highly coordinated care without meeting the usual research definition. Accurate language serves clinical decisions rather than assigning a fixed identity or prognosis.
II. What is an adequate antidepressant trial?
Adequacy means an appropriate medication was tried at a therapeutic or sufficiently tolerated dose for long enough, with enough actual exposure to judge its effect. Six to eight weeks at an adequate dose is a frequently used study convention, although the interval varies with the medication, dose titration, illness severity, adherence, and clinical risk. It is not a requirement to wait silently for eight weeks when symptoms are deteriorating. NICE recommends active reassessment when there is no response after four weeks at a recognized therapeutic antidepressant dose. NICE further-line recommendations.
A prescription history alone can overestimate treatment exposure. A medication that was collected only once, taken intermittently, stopped very early because of adverse effects, or never titrated to a potentially effective dose may count as an unsuccessful attempt but not an adequate efficacy trial. An intolerable drug still matters, because tolerance constrains later decisions. Clinicians should distinguish inadequate exposure, unacceptable side effects, and inadequate effect despite exposure.
1. Reconstructing the treatment timeline
A systematic record includes the generic name of each drug, maximum and sustained dose, duration, missed doses, symptom changes, adverse effects, reason for stopping, and whether the trial occurred during the current episode. A timeline should also record psychotherapy type, attendance, goals, completion, barriers, and measurable benefits. Pharmacy records, patient notes, earlier clinician correspondence, and a family member's observations, with consent, can help reconstruct uncertain periods.
The clinician may discover that one apparently failed treatment produced substantial benefit, another was never fully tried, and a third was interrupted for financial reasons. These facts are essential because they change both the TRD label and the safest next step. NICE specifically calls for reassessment of personal, social, environmental, physical, other mental health, and treatment-adherence factors when response has been limited. NICE NG222, section 1.9.
2. Does psychotherapy have to fail?
The conventional two-antidepressant definition does not require two failed psychotherapies. It consequently leaves out important evidence about psychological interventions. Someone can meet a conventional TRD threshold without ever receiving a structured course of cognitive behavioral therapy (CBT) or another evidence-based treatment. Another person may have had multiple psychological treatments and severe persistent symptoms without satisfying the medication-based definition. Both histories deserve individualized care. CANMAT guideline.
III. Why a diagnosis review comes before the next treatment
When adequate interventions have not worked, clinicians should revisit the underlying diagnosis, the current episode, possible bipolarity, safety needs, coexisting conditions, physical health, and current substances or medicines. Questionnaire scores support measurement, but they cannot determine the diagnosis or reliably reveal why an individual is not improving. A complete evaluation uses a clinical interview, course history, examination when indicated, and collaborative care planning. NICE guideline; NIMH depression information.
1. Bipolar disorder, mania, hypomania, and mixed features
Depressive episodes also occur in bipolar I and bipolar II disorders. Past hypomania or mania may have gone unrecognized because the person presented primarily with depression. Questions about unusually elevated or irritable mood, increased activity or energy, reduced need for sleep, marked changes in decisions, impulsivity, and episodes recognized by other people are therefore important. Mixed features can also alter assessment and safety. If bipolar disorder is diagnosed, treatment follows a different evidence base; repeating antidepressant-only strategies without recognizing bipolarity can create risks. The VA/DoD depression guideline emphasizes diagnostic differentiation.
2. Psychotic symptoms, catatonia, and urgent needs
Depression with psychotic features may involve delusions or hallucinations. Severe agitation, marked psychomotor slowing, catatonia, refusal of food or fluids, and inability to maintain basic self-care can signal a need for rapid specialist assessment. NICE describes specialist treatment of psychotic depression and considers ECT for severe depression when a rapid response is necessary or other treatments have not worked. These presentations warrant an individually assessed safety and treatment setting. NICE recommendations.
3. Persistent depressive disorder and other diagnoses
Persistent depressive disorder (dysthymia) describes a prolonged pattern of depressed mood and associated symptoms. Major depression can also have a chronic or recurrent course. Differential diagnosis includes conditions associated with anxiety, trauma, obsessive-compulsive symptoms, substance use, neurocognitive changes, sleep disorders, and medication effects. The goal is to identify all clinically relevant contributors, rather than attributing every symptom automatically to resistance. NIMH.
A person may have clinically significant anxiety together with depression. The relationship, and how it changes treatment planning, is explored in Anxiety and Depression: Why They Commonly Co-Occur. Previous adversity can matter for care formulation without proving a special neurobiological subtype of TRD; see Childhood Trauma and Depression.
4. Physical illness and medication effects
Thyroid disease, anemia, sleep apnea, chronic pain, neurological and endocrine illnesses, and medications or substances can contribute to mood, energy, sleep, and cognition. Clinicians order targeted investigations based on the history, examination, and clinical indications. No general blood panel independently diagnoses TRD. Drug interactions, substance use, alcohol, and severe insomnia may affect effectiveness and tolerability. Addressing them can improve function even while depression-specific care continues. VA/DoD guideline.
IV. Why antidepressants sometimes do not work
Depression is heterogeneous. Some people receive incomplete treatment exposure because of adverse effects, cost, access, stigma, confusing instructions, or practical obstacles. Others have multiple coexisting problems, severe or chronic illness, ongoing social stresses, or a biological and psychosocial profile that is poorly responsive to the intervention used. Sometimes a well-chosen and well-delivered treatment simply provides little benefit. No single currently established mechanism explains all nonresponse. CANMAT evidence review.
Neither nonresponse nor a TRD label proves a specific serotonin deficiency, inflammatory disease, genetic defect, abnormal brain scan, or permanent inability to recover. Group associations involving neural circuits, immune markers, metabolism, and genetics are scientifically relevant, but none is an accepted stand-alone diagnostic test or treatment selector for an individual with TRD. Clinical history and repeated outcome assessment remain central to individualized care.
V. A collaborative treatment algorithm
Once the diagnosis, trial adequacy, and urgent risks have been reconsidered, next steps can be organized into four broad decisions: optimize an inadequately tested strategy; switch to another evidence-based treatment; augment a partially effective strategy; or refer for a specialized intervention. These are decision categories, not a mandatory sequence. Severe psychotic depression or a crisis may require rapid specialist treatment regardless of the conventional number of past trials. NICE; VA/DoD.
1. Optimization
If a current antidepressant helps and is tolerated, a prescriber may review whether dosage and treatment duration are appropriate, whether interactions are reducing effectiveness, and whether side effects or missed doses can be addressed. Improving psychotherapy access, treating another medical problem, or arranging reliable follow-up can also matter. Escalating the dose is not automatically better: potential benefit must be balanced against increasing adverse effects. The clinician specifies what improvement would justify continuing the approach and when to evaluate it. NICE NG222.
2. Switching an antidepressant
A switch can involve another drug within the same class or a drug with a different pharmacological profile. Previous benefit, treatment tolerance, drug interactions, sleep and appetite changes, sexual side effects, medical comorbidity, overdose risk, and patient preference affect selection. Some transitions require tapering, cross-tapering, or a washout period. Stopping suddenly can cause antidepressant discontinuation symptoms and may complicate assessment of recurrence. Switching to or from monoamine oxidase inhibitors requires specialist precautions. NICE recommendations.
3. Augmenting an antidepressant
Augmentation means adding another treatment while keeping an antidepressant that has produced useful but insufficient improvement. Examples include an evidence-based psychotherapy, selected second-generation antipsychotics, lithium in appropriate cases, and other specialist strategies. Combining drugs can increase adverse effects, interactions, and monitoring requirements. Which augmentation is supported depends on the exact patient group and medication; the presence of a drug in a guideline is not an individual prescription. NICE combination treatments.
4. Revising or adding psychotherapy
CBT, behavioral activation, interpersonal psychotherapy, and other structured psychological treatments may reduce depression, improve coping, and address problems not resolved through medication. A later-line review asks which therapy was actually delivered, what its target was, whether sufficient sessions were available, whether it was tolerable or accessible, and what changed. An adequate pharmacological trial does not establish that psychological approaches will fail. NICE includes switching or combining psychological treatment in later-line care. NICE NG222.
5. Shared decisions and the next review date
The best option depends on benefits, harms, medical risks, functioning, time commitment, cost, insurance, transportation, cultural context, and personal priorities. A documented plan includes the chosen intervention, its therapeutic goal, side-effect monitoring, a realistic reassessment interval, and what happens if it is ineffective. It should also address sleep, work, relationships, housing or financial burdens, and primary-care coordination when relevant.
VI. What trials tell us about later-line medications
Randomized trials help compare options for groups of patients, but their eligibility criteria matter. In the VAST-D randomized trial, 1,522 predominantly male U.S. veterans with major depressive disorder and at least one inadequate antidepressant course were assigned to switching to bupropion, adding bupropion, or adding aripiprazole. By 12 weeks, the proportions meeting the trial's remission criterion were 22.3%, 26.9%, and 28.9%, respectively. Aripiprazole augmentation had a modest statistically significant advantage over switching to bupropion, while it also brought clinically important adverse effects. Because participants could enter after only one prior inadequate course, VAST-D does not represent strict two-failure TRD exclusively.
The OPTIMUM trial focused on adults aged 60 or older with treatment-resistant depression. In its initial step, augmentation with aripiprazole improved psychological well-being more than switching to bupropion; the study also examined bupropion augmentation and, in a later step, lithium augmentation or a switch to nortriptyline. These findings highlight age-specific choices and adverse-effect concerns rather than identifying a drug that works best for everyone.
1. Antipsychotic augmentation
Selected second-generation antipsychotics can be prescribed adjunctively for major depressive disorder under appropriate indications and specialist or qualified prescriber supervision. Aripiprazole and some other agents have supporting controlled trials. Monitoring may include akathisia, movement symptoms, sedation, weight change, metabolic effects, and individual interaction risks. Benefit shown in adjunctive MDD trials should not be extended automatically to every agent, dose, or TRD subgroup. VAST-D; NICE.
2. Lithium augmentation
Lithium can be considered in selected patients, commonly with specialist oversight. It requires blood-level monitoring and attention to kidney function, thyroid function, fluid balance, interactions, and toxicity. The margin between therapeutic exposure and harmful exposure can be narrow. Pregnancy-related considerations and significant medical illness may substantially change the decision. It should never be added or discontinued independently. NICE lithium monitoring recommendations; OPTIMUM.
3. Specialist antidepressants and combinations
Tricyclic antidepressants and monoamine oxidase inhibitors may be appropriate in selected later-line circumstances but involve important safety challenges, including cardiovascular or anticholinergic effects, dietary and drug interactions, and overdose hazards. Thyroid-hormone augmentation has been investigated and may sometimes be considered with specialist input; evidence and patient selection vary. These options require a clear diagnostic rationale and documented monitoring plan. NICE; VA/DoD.
VII. How effective are advanced treatments?
A systematic review and network meta-analysis of 69 randomized controlled trials, involving 10,285 adults and 25 interventions, found higher short-term response than placebo or sham for ECT, ketamine, rTMS, theta-burst stimulation, aripiprazole, and minocycline. The authors identified varying strength and certainty across interventions; trials excluded bipolar and psychotic depression. Some treatment estimates were based on small evidence networks and indirect comparisons. The finding for minocycline is not a recommendation for routine antibiotic treatment of depression. ECT, TMS, medications, and ketamine differ substantially in clinical roles and safety requirements.
1. Electroconvulsive therapy (ECT)
ECT is a medically supervised treatment in which a brief electrical stimulus induces a controlled therapeutic seizure under general anesthesia and muscle relaxation. It is among the established options for severe depression, particularly when a rapid response is needed, other interventions have failed, or symptoms present immediate serious health risks. Psychotic depression and some catatonic presentations are important specialist indications. NICE recommends considering ECT based on the person's preferences, urgency, and previous response. NICE ECT recommendations.
An ECT course requires medical and anesthesia assessment, consent procedures, repeated sessions, and planning after improvement. Confusion and memory-related adverse effects deserve explicit discussion; some cognitive problems can persist and individual risk depends on the treatment and patient. Relapse after acute response is possible, so continuation treatment is important. ECT is not simply a stronger version of taking an antidepressant; it is a distinct intervention with a specific risk-benefit profile.
2. Repetitive transcranial magnetic stimulation (rTMS)
rTMS uses a magnetic coil positioned near the scalp to deliver a patterned magnetic field, stimulating targeted cortical networks without general anesthesia. It is used in depression that has not improved sufficiently with standard treatments. A course usually requires multiple appointments, and treatment parameters, availability, and insurance coverage vary. Common adverse effects include scalp discomfort or headache; seizures are rare but clinically relevant. History of seizures, implanted devices, and other contraindications require specialist screening. VA/DoD guideline; Saelens and colleagues.
Theta-burst stimulation uses a more condensed patterned magnetic stimulation protocol and can reduce per-session time in supported settings. This does not mean every shortened protocol is equally effective or available. A specialist should explain the method, response assessment, maintenance options, and the plan if symptoms return.
3. Vagus nerve stimulation and experimental approaches
Implanted vagus nerve stimulation is a more invasive option evaluated in particularly chronic or highly treatment-exposed patients. It involves implantation and longitudinal device management, and availability and reimbursement depend on regulatory and clinical criteria. Deep brain stimulation and other experimental stimulation methods should be distinguished from standard indicated treatment. A research result or device authorization in a particular setting cannot be generalized into a universal next-step recommendation. CANMAT guideline.
VIII. Ketamine and esketamine
Ketamine-related interventions have attracted attention because some patients experience symptom improvement more quickly than with standard antidepressant treatment. Intravenous racemic ketamine and intranasal esketamine are different products, with distinct approvals, protocols, and evidence bases. A treatment offered by a clinic or online service is not necessarily an FDA-approved depression treatment. Monitoring, medical screening, substance-related risks, and maintenance planning are essential. FDA-approved esketamine prescribing information.
1. Intranasal esketamine in the United States
As confirmed in the September 2026 U.S. prescribing information, Spravato (esketamine) nasal spray is approved for treatment-resistant depression in adults as monotherapy or in conjunction with an oral antidepressant. This monotherapy option was added in 2025 and is important because older articles sometimes say an oral antidepressant must always accompany esketamine for TRD. A separate labeled indication addresses depressive symptoms in adults with MDD and acute suicidal ideation or behavior, where it is used alongside an oral antidepressant. The label explicitly states that efficacy in preventing suicide or reducing suicidal ideation or behavior has not been demonstrated. DailyMed current U.S. label.
Esketamine must be administered under healthcare supervision through a restricted REMS program. Risks include sedation, dissociation, respiratory depression, transient blood pressure elevation, abuse or misuse, and antidepressant-associated warnings concerning suicidal thoughts and behavior in younger patients. The label requires monitoring for at least two hours after administration, with assessment for continued risks. Transportation and next-day activity advice are part of the care plan. It is not approved for pediatric patients. Official labeling.
U.S. FDA approval and treatment recommendations in other health systems must be distinguished. NICE's January 2026 surveillance report noted that its earlier U.K. technology appraisal did not recommend esketamine for TRD because of clinical and cost-effectiveness uncertainties. Regulatory approval, guideline recommendation, reimbursement, and availability are separate decisions. NICE NG222 surveillance.
2. Intravenous ketamine
Intravenous racemic ketamine is used off-label for depression in some U.S. specialist services. Randomized evidence suggests a rapid antidepressant effect in selected adults, but questions remain about repeated treatment, optimal long-term maintenance, cumulative risks, and generalizability. In the ELEKT-D study, intravenous ketamine met the study's criterion for noninferiority to ECT in enrolled adults with nonpsychotic treatment-resistant depression. The result should not be transferred automatically to psychotic depression, other ketamine formulations, or every clinical setting.
The FDA's compounded-ketamine safety communications describe concerns about products marketed for psychiatric disorders, including sedation, respiratory problems, dissociation, blood-pressure changes, and misuse. Unsupervised home administration is fundamentally different from the medical monitoring established for licensed esketamine. A patient should review any ketamine offer with a clinician and understand which formulation is being used and why.
3. Rapid improvement and long-term recovery
A rapid reduction in symptoms does not itself establish sustained remission. Treatment planning must include continued care, symptom and functioning measures, side-effect assessment, relapse-prevention choices, and a defined review point. Short-term trial response percentages for ketamine, ECT, TMS, or augmentation cannot be compared as if participant populations, trial duration, controls, and outcome definitions were identical. Saelens et al..
IX. Emerging treatments, pharmacogenetics, and research uncertainty
Psilocybin-assisted interventions remain the subject of clinical investigation. In a randomized trial reported in the New England Journal of Medicine, a 25-mg psilocybin dose delivered with psychological support produced a short-term improvement compared with a very low dose in some participants with treatment-resistant depression, but sustained effectiveness and adverse effects require further evidence. As of October 2026, psilocybin is not an FDA-approved prescription therapy for depression. Research trials and various state-level legal frameworks do not amount to federal approval. FDA psychedelic drug development information.
Pharmacogenetic testing may sometimes help interpret how a particular drug is metabolized or a known interaction, especially when unusually strong adverse effects occur. It is not a generally validated diagnostic test for TRD or a guaranteed way to identify an effective antidepressant for each person. Similarly, commercial 'precision psychiatry' blood biomarkers, microbiome claims, and brain scans need evidence that using the result improves real clinical outcomes. The mechanistic plausibility of a test is not sufficient to establish usefulness. CANMAT.
X. Comparing advanced treatment options
An ECT referral may be appropriate when depression is severe, psychotic, medically dangerous, or urgently requires a response. rTMS can be attractive when a non-anesthetic outpatient intervention is feasible and compatible with the patient's clinical history. Medication augmentation can make sense when an existing antidepressant provides meaningful but incomplete benefit. Esketamine requires a specialized certified administration environment and medical monitoring. Each involves a distinct schedule, cost, adverse-effect profile, and continuation plan. NICE; VA/DoD.
A useful clinical comparison asks what benefit is expected and how likely it is given the person's history, what risks matter most, how rapidly change is needed, and how remission would be maintained. A person living far from a treatment center may find daily attendance impractical; someone with significant cognitive concerns may attach special importance to discussing memory effects of ECT. Eligibility, availability, medical safety, and the person's informed preference are part of effectiveness in ordinary life.
XI. Monitoring whether a treatment is working
Progress should be evaluated through symptoms, day-to-day functioning, adverse effects, safety, and personally meaningful goals. A PHQ-9 or similar scale may help measure change consistently, but it is a measurement tool rather than a self-diagnostic test or a stand-alone definition of treatment resistance. Changes in sleep, motivation, appetite, concentration, social connection, and work or caregiving ability may provide information a single score misses. The Hub's Depression Screening: What a Positive Questionnaire Result Means explains these limits.
Care teams can agree on a review schedule based on medication initiation, titration, psychotherapy progress, or a procedure's protocol. Monitoring includes whether the plan is feasible and whether it helps the person resume valued activity. Improvement sometimes comes in stages; if the chosen therapy is not helping, the plan needs timely reassessment rather than indefinite repetition. NICE monitoring and further-line recommendations.
XII. Safety and situations requiring urgent attention
Suicidal thoughts, intention or planning to self-harm, emerging psychosis, mania or severe agitation, inability to eat or drink, and inability to maintain basic safety require prompt clinical assessment. Immediate danger warrants emergency services or the nearest emergency department. In the United States, 988 provides crisis support; local services elsewhere vary. A person receiving treatment should contact their care team when symptoms suddenly deteriorate instead of waiting for a routine appointment. NIMH depression resource.
Antidepressants, lithium, antipsychotics, and other prescribed medications should not be stopped, increased, or combined without professional guidance. Antidepressant withdrawal can involve dizziness, insomnia, sensory disturbances, nausea, anxiety, or flu-like symptoms, and it should be differentiated from recurrence of depression. Some medication changes carry significant interaction risks. Unusual energy, reduced need for sleep, activation, or emerging suicidal thoughts after a treatment change merit reassessment. NICE medication discontinuation guidance; NIMH medication information.
XIII. Children, older adults, and medical complexity
1. Adolescents and children
Adult two-medication definitions and adult advanced-treatment results should not be applied uncritically to children or teenagers. Age-specific diagnosis, developmental stage, family involvement, psychotherapy, appropriate medication labeling, adverse-effect monitoring, and pediatric specialist evaluation matter. Esketamine nasal spray is not approved for children in the United States. Treating a young person whose symptoms persist should follow age-appropriate clinical pathways, including monitoring for worsening mood, activation, or suicidal thinking. Official esketamine label.
2. Older adults
In later life, polypharmacy, falls, cognition, cardiovascular health, kidney function, and access to regular appointments may have greater influence on treatment choice. The OPTIMUM randomized trial provides evidence directly relevant to treatment-resistant geriatric depression, while also illustrating that augmentation and medication switches need individual monitoring. ECT may be indicated in older patients, with careful anesthesia and cognitive risk assessment.
3. Pregnancy and the postpartum period
Treatment in pregnancy or after childbirth demands a separate evaluation of the risks and benefits of treatment, untreated illness, breastfeeding considerations, and available specialist support. Evidence and regulatory indications vary greatly by intervention. Unipolar TRD decisions cannot simply be copied into perinatal care. Medication decisions should be coordinated with clinicians experienced in reproductive mental health, and urgent symptoms require a timely response. NICE adult depression recommendations.
4. Chronic illness, substance use, and social barriers
Chronic medical disease, alcohol or other substance problems, painful conditions, unstable housing, financial strain, and inaccessible care can complicate recovery. Treating a contributing problem and coordinating primary care, psychiatry, psychological treatment, and community support may improve function. These factors must be assessed with clinical specificity rather than being used to dismiss the depressive disorder itself. VA/DoD clinical guideline.
XIV. A practical plan after two unsuccessful treatments
The first useful step is to request a structured review with the current prescriber or an appropriately qualified mental health clinician. Bring a treatment timeline, relevant previous medical records, medication doses and durations, adverse effects, psychotherapy history, other diagnoses, prescribed and nonprescribed substances, and notes about how symptoms and functioning changed. Clarify whether the past two treatment courses truly met adequacy criteria and whether bipolar symptoms, physical illness, or urgent safety issues require investigation.
Useful questions include: What diagnosis best fits my history? Which trials were adequate, and which were interrupted or poorly tolerated? What improved even slightly? What are the expected benefits and major harms of switching, augmentation, psychotherapy, rTMS, ECT, or esketamine? Which approaches are locally available and covered by insurance? What is the monitoring plan, and when will we review results? What alternative would be considered if the next intervention does not help? Such questions turn an intimidating list of possibilities into a structured shared decision. NICE NG222.
XV. Supporting someone with persistent depression
Loved ones can support care by listening, helping organize records and appointments when invited, assisting with practical needs, maintaining connection, and observing changes in safety or basic functioning. Complex depression can be exhausting for the person and their support network. Recovery may involve repeated treatment adjustments and uncertain schedules. Supporters can communicate encouragement without demanding immediate improvement and can seek guidance for their own stress.
Consent and autonomy matter. Sharing information with the clinical team should take the person's preferences and confidentiality into account, except where an immediate safety concern requires urgent intervention. A family member can help describe function and treatment history but cannot replace the person's clinical evaluation. NIMH guidance.
XVI. Three illustrative clinical situations
1. Early intolerance after a first prescription
An adult stops a new antidepressant after ten days because of severe nausea. Their depressive symptoms remain. This episode documents an important tolerability problem, but it usually cannot be counted as a full adequate efficacy trial for a strict TRD definition. A clinician might review alternative medication strategies, psychotherapy, symptom management, and informed preferences before describing the depression as medication-resistant.
2. Two therapeutic trials and persistent impairment
A second person has received two sustained therapeutic antidepressant courses during the current episode. Mood has improved slightly but severe anhedonia and inability to function remain. A clinician can document inadequate response, revisit diagnostic and medical factors, consider psychotherapy or augmentation, and evaluate specialist procedures depending on preferences and urgency. The TRD label should make the treatment plan more comprehensive.
3. Persistent depression and a possible hypomanic history
A third person reports several unsuccessful antidepressants but, during detailed evaluation, describes past episodes of unusually high energy, strikingly reduced need for sleep, impulsive activity, and marked behavioral change. The immediate need is bipolar diagnostic assessment. Another routine antidepressant switch without considering the episode history could be clinically inappropriate. These are explanatory examples, not criteria for self-diagnosis. CANMAT; VA/DoD.
XVII. Frequently asked questions
1. Is treatment-resistant depression permanent?
The label records previous inadequate response, not an irreversible prognosis. Additional treatments can help, and some people achieve remission after changing or augmenting care. A precise history and reassessment help select the next approach. CANMAT.
2. Is one failed antidepressant enough to have TRD?
Usually not under the common research definition requiring at least two adequate antidepressant trials. One unsuccessful treatment is nonetheless a valid reason for clinician-led reassessment, particularly when symptoms are disabling or safety is changing. Some clinical trials of later-line strategies include people after only one failed course. VAST-D.
3. What if a medication helps, but depression remains?
Partial response is clinically important. A prescriber may consider optimization, augmentation, psychotherapy, a medication switch, or referral. The choice depends on how much benefit exists, tolerability, remaining impairment, prior trials, and the person's goals. NICE.
4. Is there a blood test or brain scan for TRD?
No laboratory test or brain scan independently diagnoses TRD or reliably chooses the best treatment for every person. Targeted testing can investigate a suspected medical contributor. Treatment-history evaluation and clinical diagnostic assessment remain essential. CANMAT.
5. Can TRD be treated without another antidepressant?
Depending on the circumstances, psychotherapy, TMS, ECT, or specialist interventions may be appropriate. In the United States, intranasal esketamine for adult TRD can be used as monotherapy or together with an oral antidepressant under the approved labeling and supervision requirements. Eligibility requires professional assessment. DailyMed label.
6. Is TMS better than ECT?
They have different clinical roles, practical demands, and adverse effects. ECT is particularly relevant when depression is severe, psychotic, or a rapid response is needed, while rTMS is a non-anesthetic outpatient procedure for selected patients. Comparative effectiveness cannot be reduced to a universal ranking. NICE; systematic review.
7. Are ketamine and esketamine the same?
No. Intravenous racemic ketamine is used off-label for depression, while intranasal esketamine has FDA-approved adult indications, specific clinical monitoring, and a REMS program. Different products and delivery settings require separate evidence evaluation. FDA-authorized label.
8. Is psilocybin approved for treatment-resistant depression?
Psilocybin remains investigational for depression in the United States as of October 2026 and has not received FDA approval as a depression medication. Promising trial signals require confirmation, long-term evaluation, and attention to adverse effects and psychological support. FDA psychedelic drug development.
9. When should someone ask for a specialist referral?
A referral can be appropriate when meaningful impairment persists despite adequate treatment, diagnosis is uncertain, combination medicines or procedures are being considered, or serious adverse effects complicate care. Immediate safety concerns require urgent assessment rather than an ordinary appointment queue. NICE.
10. How long should treatment continue before reassessment?
The appropriate interval depends on dose, intervention, symptom trajectory, and safety. NICE recommends reassessing nonresponse after about four weeks at a recognized therapeutic antidepressant dose, while evaluation of a completed adequate treatment course may require additional time. A person should not remain indefinitely on a treatment that is unsafe or ineffective without clinical review. NICE further-line guidance.
XVIII. Conclusion
Treatment-resistant depression is a signal for a more precise and coordinated treatment plan. Establish the diagnosis, verify actual prior exposure and response, reassess bipolarity and other contributors, address immediate safety, then compare the benefits and harms of switching, augmentation, structured psychotherapy, brain stimulation, ketamine-related treatments, and continued recovery support. Long-term progress includes functioning and sustained remission as well as symptom relief. CANMAT; NICE; VA/DoD.
Related Articles
References
Food and Drug Administration. (2023). Compounding risk alerts: Compounded ketamine products. U.S. FDA.
Food and Drug Administration. (2026). Psychedelic drugs: Clinical investigation resources. U.S. FDA.
Goodwin, G. M., et al. (2022). Single-dose psilocybin for a treatment-resistant episode of major depression. New England Journal of Medicine, 387, 1637–1648. https://doi.org/10.1056/NEJMoa2206443.
Lam, R. W., et al. (2024). Canadian Network for Mood and Anxiety Treatments (CANMAT) 2023 update on clinical guidelines for management of major depressive disorder in adults. Canadian Journal of Psychiatry, 69(9), 641–687. https://doi.org/10.1177/07067437241245384.
Lenze, E. J., et al. (2023). Antidepressant augmentation versus switch in treatment-resistant geriatric depression. New England Journal of Medicine, 388, 1067–1079. https://doi.org/10.1056/NEJMoa2204462.
Mohamed, S., et al. (2017). Effect of antidepressant switching vs augmentation on remission among patients with major depressive disorder unresponsive to antidepressant treatment: The VAST-D randomized clinical trial. JAMA, 318, 132–145. https://doi.org/10.1001/jama.2017.8036.
National Institute for Health and Care Excellence. (2022). Depression in adults: Treatment and management (NG222). https://www.nice.org.uk/guidance/ng222/chapter/Recommendations.
National Institute for Health and Care Excellence. (2026). January 2026 exceptional surveillance of depression in adults: Treatment and management. Surveillance document.
National Institute of Mental Health. (n.d.). Depression. Official health information.
National Institute of Mental Health. (n.d.). Mental health medications. Official health information.
Saelens, J., et al. (2025). Relative effectiveness of antidepressant treatments in treatment-resistant depression: A systematic review and network meta-analysis of randomized controlled trials. Neuropsychopharmacology, 50, 913–919. https://doi.org/10.1038/s41386-024-02044-5.
Singh, J. B., et al. (2023). Ketamine versus ECT for nonpsychotic treatment-resistant major depression. New England Journal of Medicine. PubMed record.
U.S. Department of Veterans Affairs and U.S. Department of Defense. (2022). Management of major depressive disorder: Clinical practice guideline. https://www.healthquality.va.gov/guidelines/MH/mdd/.
U.S. National Library of Medicine, DailyMed. (2026). Spravato (esketamine) nasal spray: U.S. prescribing information, updated September 22, 2026. Official current label.