When standard antidepressants haven't worked, TMS and ketamine are the two most established next-step options for treatment-resistant depression. Patients often ask which one is "better." The honest answer is that they work through different biological mechanisms, on different timelines, and tend to suit different situations, so the right choice depends on your history and goals rather than one being universally superior.
How TMS Works
Transcranial Magnetic Stimulation uses focused magnetic pulses, similar in strength to those used in MRI machines, to activate the left dorsolateral prefrontal cortex, a brain region involved in mood regulation that is typically underactive in depression. At Health 210 Psychiatry, we use Deep TMS by Brainsway across all four of our San Antonio and Boerne locations, which uses an H-coil to reach deeper and broader brain structures than standard coil systems. It's non-invasive, requires no anesthesia, and carries no systemic medication side effects since nothing is injected or ingested.
A course involves 5 sessions per week for 6-9 weeks, with each session lasting 19-37 minutes. You remain awake throughout and can return to normal activities immediately afterward.
How Ketamine Works
Ketamine is an FDA-approved anesthetic that works on the glutamate system, the brain's most abundant excitatory neurotransmitter, rather than the serotonin or norepinephrine pathways that standard antidepressants target. This different mechanism is why it can help some patients who haven't responded to SSRIs or SNRIs. Research shows it's effective for roughly 70% of patients with treatment-resistant depression, generally defined as having failed two or more adequate antidepressant trials.
Treatment is delivered as an IV or IM infusion at a sub-anesthetic dose, meaning you're awake but in a deeply relaxed, dissociative state during the session itself. A typical induction series is 6 infusions over 2-3 weeks, followed by booster infusions as needed to maintain results.
Timeline: What to Expect
This is where the two treatments differ most. Ketamine can produce noticeable effects within hours of an infusion for some patients, dramatically faster than the 4-8 weeks typical of standard antidepressants. TMS works more gradually. Most patients notice change over the course of their 6-9 week session schedule rather than after a single visit. Neither timeline is a guarantee, response varies by individual, but it's a meaningful factor if urgency (for example, in cases involving acute suicidal ideation) is part of the clinical picture.
Who Tends to Do Better With Each
TMS is often a good fit for patients who want a drug-free option with no dissociative effects and can commit to near-daily visits for several weeks. Ketamine is often considered for the most severe or urgent cases, or for patients who haven't found adequate relief through standard psychiatric care and want a faster-acting option, understanding that each infusion requires being monitored during the dissociative period. Some patients ultimately use both, sequentially or alongside ongoing medication management, rather than choosing just one.
The Bottom Line
Neither treatment is a first-line option; both are typically considered after standard antidepressants and therapy haven't provided enough relief. The right starting point depends on your treatment history, how quickly you need relief, and your personal preference around the two very different treatment experiences. A board-certified psychiatrist can walk through your specific history and help you decide which makes sense to try first.
Learn more about our Deep TMS program or our ketamine therapy program, or reach out and we'll help you figure out the right next step.
