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Research shows that ketamine can lift depression symptoms much faster than usual antidepressants. Several randomized trials found benefits within hours to a day after treatment, especially for people whose depression did not get better with other medicines. A nasal form (esketamine) has also been approved for hard-to-treat depression in some cases. What is less certain is whether ketamine specifically fixes low energy or low motivation. Most studies measure overall depression scores, not single symptoms. Researchers also worry about short-term side effects and need more work on long-term safety, the best dosing plan, and whether combining ketamine with therapy or brain stimulation helps more or less.
Treatment-resistant depression means depression that does not get better after usual treatments. Scientists do not all agree on one clear definition, which makes it hard to know exactly how common it is or which treatments work best. Using the definition that regulators often use, about 30% of people with depression…
Researchers tested repeated subcutaneous (under-the-skin) injections of racemic ketamine in people whose depression had not improved after at least two antidepressant trials. People got injections twice a week for 4 weeks and neither participants nor the raters knew which drug they were getting. When the study allowed higher, response-guided ketamine…
