What Is Treatment-Resistant Depression? Signs You Have It and What to Do Next

You finally got help. You went to the appointments. You took the medication and waited the weeks they told you it would take. And you are still not better.

That experience has a name. Treatment-resistant depression does not mean your depression is untreatable. It means the standard first steps have not worked, and the clinical path forward looks different from what you have tried.

About 30% of people with major depressive disorder meet the definition. If you are in that group, you need clinical information that goes beyond “let’s try another antidepressant.” This guide gives you the clinical picture: what TRD means, how to tell whether you actually have it, and what the evidence-based options are after standard antidepressants have not been enough.

What This Page Covers

• The clinical definition of treatment-resistant depression
• How to determine whether prior antidepressant trials were actually adequate
• The most important differential diagnoses to rule out
• The clinical options after two failed antidepressants
• How esketamine, TMS, and ECT fit into the treatment algorithm
• What continuity of monitoring has to do with TRD outcomes
• What SiggyMD’s model addresses in the TRD picture

The Clinical Definition

The US Food and Drug Administration and the European Medicines Agency have adopted the most used definition of TRD: inadequate response to a minimum of two antidepressants despite adequacy of the treatment trial and adherence to treatment.

“Adequate” has two components: dose and duration. An adequate trial requires a therapeutic dose maintained for at least six to eight weeks. A trial that was stopped at three weeks due to side effects, or a trial at a sub-therapeutic dose, does not count as an adequate failure.

Treatment-resistant depression is most commonly defined as absence of remission using validated scoring tools despite trials of two or more antidepressant medications at adequate dose, duration, and adherence.

Approximately 30% of people with major depressive disorder meet this definition. It is currently estimated that at least 30% of persons with depression meet this definition.

Before Accepting the Label: Pseudo-Resistance

One of the most important clinical considerations in apparent TRD is distinguishing true treatment resistance from pseudo-resistance. A significant percentage of persons with TRD are actually pseudo-resistant, for example due to inadequacy of treatment trials or non-adherence to treatment.

The most common causes of pseudo-resistance:

Trials that were not long enough. Six to eight weeks at a therapeutic dose is the minimum. Many patients stop at three to four weeks because they feel nothing is happening. That is not a failed trial.

Doses that were too low. Starting doses are not always therapeutic doses. If a medication was started and not titrated upward to a therapeutic range before stopping, the trial was incomplete.

Poor adherence. Nonadherence rates for antidepressant medications have been estimated to be 46%. Medication that is not taken consistently cannot produce consistent effects.

Drug interactions. Some concurrent medications reduce antidepressant blood levels through enzyme induction. A prescriber can check for this.

Before progressing to complex TRD interventions, confirming that prior trials were genuinely adequate is a necessary and often valuable clinical step.

Rule Out These Conditions First

Bipolar Disorder

Diagnosis of bipolar disorder should specifically be considered; patients should be screened for symptoms of mania or hypomania because up to 25% of patients presenting with depression or anxiety in a primary care setting are diagnosed with bipolar disorder. Bipolar disorder is commonly misdiagnosed as unipolar depression, particularly when the patient presents between episodes. SSRI monotherapy in bipolar disorder can destabilize mood and produce rapid cycling. If there is any personal or family history of elevated, expansive, or irritable mood episodes, screening for bipolar disorder is critical before the next treatment step.

Medical Conditions

Consider physical health conditions that can sometimes cause or worsen depression, such as thyroid disorders, chronic pain, or heart problems. Hypothyroidism produces depressive symptoms. Untreated sleep apnea produces fatigue and low mood that mimics and exacerbates depression. Chronic pain conditions reduce quality of life in ways that look like treatment-resistant depression. Screening for these is part of a thorough TRD evaluation.

Personality Disorders and Trauma

82.9% of TRD patients in one clinical sample had at least one other psychiatric diagnosis, and 82.2% had at least one personality disorder. Personality disorders, particularly borderline personality disorder, do not respond well to antidepressants as primary treatment. Complex PTSD and unresolved trauma histories require treatment approaches that address the underlying history, not just the depressive symptoms on the surface.

Clinical Options After Two Failed Antidepressants

Switching Medication Class

Switching medications is a reasonable strategy, especially for patients experiencing adverse effects or intolerance to the initial antidepressant, or lack of response after appropriate titration over four to twelve weeks.

Switching from one SSRI to another within the same class has modest evidence for inducing response in partial responders. Switching to a different class, such as from an SSRI to an SNRI, bupropion, mirtazapine, or a tricyclic antidepressant, may capture a different mechanistic profile more suited to the individual patient’s biology.

Augmentation

Adding a second agent to a partially effective antidepressant is a standard second-step strategy.

Treatment options include second-generation antidepressants, second-generation antipsychotics, buspirone, tricyclic antidepressants, lithium, triiodothyronine (synthetic T3 augmentation), ketamine, and esketamine.

Second-generation antipsychotics with the strongest augmentation evidence include aripiprazole (Abilify), brexpiprazole (Rexulti), cariprazine (Vraylar), and quetiapine XR (Seroquel XR). These are FDA-approved as adjunctive treatments in partial responders. Some second-generation antipsychotics are proven effective as adjunctive treatments to antidepressants in partial responders.

Lithium augmentation has decades of evidence for TRD, requires monitoring of lithium blood levels, and is particularly supported for patients with melancholic features.

Esketamine (Spravato)

Esketamine is a significant advance in TRD treatment precisely because it works through a different mechanism than all conventional antidepressants. Intravenous ketamine and intranasal esketamine, co-administered with an antidepressant, are established as efficacious in the management of TRD.

Esketamine (Spravato) is an NMDA receptor antagonist. It targets the glutamate system rather than the monoamine system (serotonin, norepinephrine, dopamine) that all conventional antidepressants address. This entirely different mechanism is why it can produce response in patients who have not responded to multiple monoamine-targeting medications.

Its onset is measured in hours rather than weeks. Esketamine nasal spray is administered in a certified healthcare setting because of monitoring requirements. It is FDA-approved specifically for treatment-resistant depression in adults, and more recently for major depressive disorder with acute suicidal ideation.

Transcranial Magnetic Stimulation (TMS)

TMS is established as effective and FDA-approved for major depressive disorder in patients with TRD. Approximately 50 to 60% of patients with treatment-resistant depression respond to a standard rTMS course. It is non-invasive, requires no anesthesia, and is administered in an outpatient setting.

TMS is typically tried before ECT in patients who have not had psychotic features or medical urgency requiring faster response.

Electroconvulsive Therapy (ECT)

ECT remains the most effective treatment for severe treatment-resistant depression, with remission rates higher than any other available intervention. It is typically reserved for patients with the most severe presentations: psychotic depression, catatonia, acute suicidality, or TRD that has not responded to multiple other interventions.

Electroconvulsive therapy is generally only considered as a treatment option in severe cases of treatment-resistant depression. It is used when medication has repeatedly failed to improve symptoms, and usually when the patient’s symptoms are so severe that they have been hospitalized. ECT requires anesthesia, is administered in hospital settings, and carries risks including short-term memory impairment. For the patients who genuinely need it, these trade-offs are clinically justified.

Why Continuous Monitoring Matters in TRD

A pattern that appears frequently in TRD histories: the patient took a medication, felt only partial improvement, and the appointment was months away. When they finally saw their prescriber, they had been living in partial relief or deteriorating for weeks. The prescriber had no visibility into what was happening day to day.

The adherence and monitoring failures that produce pseudo-resistance, and the missed escalation opportunities that allow genuine TRD to worsen, share a common root: lack of continuous clinical data.

SiggyMD’s clinical model is specifically designed around this problem. Daily check-ins capture symptom trajectories, side effect patterns, and functional changes in real time. A licensed prescriber reviews this data continuously rather than at quarterly intervals. The result is that inadequate response is identified earlier, dose adjustments are made when the data supports them, and the escalation to specialized interventions is based on an actual pattern rather than a retrospective impression.

“The patients I see who arrive at a TRD label are often patients for whom the monitoring gap was the problem,” says Daniel Montville, MD, Psychiatrist, of the SiggyMD clinical team. “Not always, but often. Two adequate trials with real-time monitoring and early dose adjustment look different from two trials where the patient was alone with side effects for six weeks before anyone asked how it was going. The outcome can be different too.”

For patients who are currently struggling with depression that has not responded to one or more medications and want a clinical conversation about next steps, start your anonymous intake with SiggyMD and a licensed prescriber will review your full clinical picture.

About SiggyMD

SiggyMD pairs a clinical AI intake with licensed prescribers for ongoing mental health care, including continuous monitoring that keeps prescribers informed between appointments. Every treatment plan is reviewed and approved by a licensed clinician. For patients with treatment-resistant or difficult-to-treat depression, that level of clinical visibility changes what is possible.

For context on specific medications used in TRD management, our guide to antidepressant classes covers the full landscape from SSRIs to newer agents.

What Members Are Saying

DW

D.W., 44

Treatment-Resistant Depression

“I had been on antidepressants for nine years across four different medications. Each one helped initially and then stopped. My new psychiatrist asked me how long each trial had actually lasted at the therapeutic dose. Two of the four turned out to be inadequate trials. We actually got the diagnosis right on the fifth medication. I had never had someone look at the history that carefully before.”

CA

C.A., 37

Major Depressive Disorder

“I was referred for esketamine after three antidepressants did not produce remission. The process was different from anything I had experienced: administered in a clinic, I felt effects within a few hours. The first session was strange but by the third week the depressive symptoms that had been with me for four years had noticeably lifted. The difference from all the prior medications was that it worked on a different system entirely.”

Member stories reflect real experiences. Names and identifying details have been changed to protect privacy. Results vary. SiggyMD is currently invite-only.

The Most Important Thing to Know

Treatment-resistant depression is a clinical observation, not a life sentence. It tells you that the first-line path did not produce remission. It does not tell you that remission is impossible.

What it does mean: the clinical conversation needs to go deeper. Were prior trials adequate? Have comorbid conditions been fully evaluated? Has the diagnosis been confirmed? And what are the specific evidence-based options for someone with your clinical history?

Those questions have answers. Start your intake with SiggyMD and a licensed prescriber will work through them with you.

Sources

1. McIntyre RS, et al. Treatment-resistant depression: definition, prevalence, detection, management, and investigational interventions. World Psychiatry. 2023;22(3):394-412.

2. Gaynes BN, et al. Depression: Managing Resistance and Partial Response to Treatment. American Family Physician. 2024;109(5):417-424.

3. Cleveland Clinic. Treatment-Resistant Depression: What It Is and Symptoms. Accessed June 2026.

4. Mayo Clinic. Treatment-resistant depression. Accessed June 2026.

5. Zhdanava M, et al. The Prevalence and National Burden of Treatment-Resistant Depression and Major Depressive Disorder in the United States. Journal of Clinical Psychiatry. 2021;82(2).

6. Ruberto VL, et al. The complexity of treatment-resistant depression: A data-driven approach. Journal of Affective Disorders. 2024.