Treatment-Resistant Depression Options: Beyond Standard Antidepressants

You finally got help. You took the medication for the weeks they told you it would take. You are still not better.

That experience has a name, and it has a clinical path forward. Treatment-resistant depression does not mean untreatable. It means the first-line options have not produced adequate response, and the conversation needs to go deeper.

What This Page Covers

• The clinical definition of TRD and how to determine whether it actually applies
• What pseudo-resistance is and why it matters before escalating
• The full range of TRD-specific options and how each works
• How esketamine, TMS, and ECT differ from one another and from conventional antidepressants
• Why augmentation and MAOIs still have a meaningful role
• How continuous monitoring reduces the gap that contributes to TRD

The Clinical Definition of TRD

Treatment-resistant depression is defined by the FDA and EMA as inadequate response to at least two antidepressants of adequate dose and duration. An adequate trial means a therapeutic dose maintained for at least 6 to 8 weeks. Trials stopped early due to side effects, or trials at sub-therapeutic doses, do not count as adequate failures.

Approximately 30% of people with major depressive disorder meet this definition. This represents millions of people who are working through a clinical challenge that standard first-line treatment cannot fully address.

Before the TRD Label: Pseudo-Resistance

One of the most important steps in TRD evaluation is distinguishing true treatment resistance from pseudo-resistance.

A significant percentage of people with apparent TRD are actually pseudo-resistant, due to inadequacy of treatment trials or non-adherence. Common causes:

• Inadequate dose: If a medication was not titrated to the therapeutic range before stopping, the trial was incomplete.
• Inadequate duration: Six to eight weeks at a therapeutic dose is the minimum. Stopping at three to four weeks is not a failed trial.
• Poor adherence: Nonadherence rates for antidepressant medications are estimated at 46%. Medication taken inconsistently cannot produce consistent results.
• Unrecognized bipolar disorder: Up to 25% of patients presenting with depression or anxiety in a primary care setting are diagnosed with bipolar disorder. SSRI monotherapy in bipolar disorder can worsen the course rather than treat it.
• Underlying medical conditions: Thyroid dysfunction, sleep apnea, and chronic pain can all maintain depressive symptoms that look like TRD.

Confirming that prior trials were genuinely adequate can reveal that what looks like TRD is actually treatable with the right approach to first-line agents.

When True TRD Is Confirmed: The Options

Switching Medication Class

After two SSRI or SNRI trials, switching to a different class addresses a different mechanistic profile. Switching medications is reasonable especially when a patient has experienced adverse effects or inadequate response after appropriate titration. Options include bupropion (NDRI), mirtazapine, tricyclic antidepressants, and vortioxetine.

Augmentation

Adding a second agent to a partially effective antidepressant is a standard second-step strategy. FDA-approved augmentation options for partial responders include atypical antipsychotics (aripiprazole, brexpiprazole, cariprazine, quetiapine XR), lithium, and thyroid hormone. Some second-generation antipsychotics are proven effective as adjunctive treatments to antidepressants in partial responders.

Esketamine (Spravato)

Esketamine represents a meaningful advance in TRD precisely because it works through a mechanism entirely different from all conventional antidepressants.

Intravenous ketamine and intranasal esketamine are established as efficacious in the management of TRD. Esketamine is an NMDA receptor antagonist targeting the glutamate system rather than the monoamine system. This different mechanism is why it can work when multiple monoamine-targeting medications have not.

Intranasal esketamine was the first FDA-approved rapid antidepressant for treatment-resistant depression. Its effects emerge within hours to days. It is co-administered with an oral antidepressant and must be taken in a certified healthcare setting due to monitoring requirements for dissociation, sedation, and blood pressure changes.

Transcranial Magnetic Stimulation (TMS)

TMS uses magnetic pulses to stimulate targeted areas of the prefrontal cortex through a different pathway than conventional antidepressants. Repetitive TMS is established as effective and FDA-approved for TRD, with accelerated theta-burst TMS also recently showing efficacy.

Response rates in TRD populations typically range from 50 to 60% with standard protocols. TMS is non-invasive, requires no anesthesia, and is administered in an outpatient setting. The mechanistic distinction is clinically important: medication failure does not predict TMS failure because the two approaches target the same problem through different pathways.

MAOIs

Monoamine oxidase inhibitors have a different mechanism than any other antidepressant class. Rather than blocking reuptake, they block the enzyme that breaks down neurotransmitters, increasing stores available for release. They uniquely increase dopamine availability, which may be particularly relevant for persistent anhedonia.

Estimates suggest 15 to 20% of patients with major depression require MAOI treatment for optimal response, but the prescription rate is less than 0.1%. They are particularly effective for atypical depression and bipolar depression. The dietary restriction concern is real but manageable with clear clinical guidance.

ECT

Electroconvulsive therapy remains the most effective treatment for severe TRD. It is typically reserved for patients with psychotic depression, catatonia, acute suicidality, or TRD that has not responded to multiple other interventions. ECT requires anesthesia and hospital-based administration. Short-term memory impairment is a genuine risk. For appropriate candidates, the severity of the condition and the effectiveness of ECT justify these considerations. ECT is underutilized relative to its evidence base.

Why Monitoring Gaps Contribute to TRD

A pattern that appears consistently in TRD histories: the patient took a medication, felt only partial improvement, and the next appointment was months away. The prescriber had no visibility into what was actually happening.

“The patients I see who arrive at a TRD label are often patients for whom the monitoring gap was part of the problem,” says Daniel Montville, MD, Psychiatrist, of the SiggyMD clinical team. “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.”

SiggyMD’s daily check-in model captures symptom trajectories, side effect patterns, and functional changes in real time. A licensed prescriber reviews this data continuously rather than at quarterly intervals. Inadequate response is identified earlier, and escalation decisions are based on an actual pattern.

About SiggyMD

SiggyMD provides clinician-reviewed care for anxiety and depression, with daily check-ins that make medication response visible between appointments. For patients who have not responded to standard antidepressants and want to explore what comes next, start your anonymous intake with SiggyMD. You can also read: What Is Treatment-Resistant Depression? and The Complete Antidepressant List.

If you are in crisis or experiencing thoughts of suicide, call or text 988 or go to your nearest emergency room.

What Members Are Saying

DW

D.W., 44

Treatment-Resistant Depression

“I had been on four antidepressants over nine years. When I finally worked with a prescriber who looked carefully at the history, two of those trials turned out to be inadequate at therapeutic dose. We re-approached the diagnosis and finally found something that worked.”

CA

C.A., 37

Major Depressive Disorder

“I was referred for esketamine after three antidepressants did not produce remission. By the third week, the depressive symptoms that had been with me for four years had visibly lifted. The difference was that it worked on a completely different system.”

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

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).

3. Caliman-Fontes AT, et al. Brain-derived neurotrophic factor serum levels following ketamine and esketamine intervention for TRD. Trends in Psychiatry and Psychotherapy. 2023.

4. Loo C, et al. Efficacy and safety of a 4-week course of repeated subcutaneous ketamine injections for TRD (KADS study). British Journal of Psychiatry. 2023;223(6):533-541.

5. Psychiatry Online. Moving on With Monoamine Oxidase Inhibitors. FOCUS. 2021;19(1).

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

Reviewed by Daniel Montville, MD, Psychiatrist | Last updated June 2026