When it comes to profound depression and post-traumatic stress disorder (PTSD), many people just can't get relief from current treatments Now there's more evidence than ever before that the anesthetic ketamine has potential as a fast-acting treatment for depression, bipolar disorder, anxiety, addiction and post-traumatic stress disorder (PTSD), with very few side effects. Ketamine is an FDA-approved anesthetic that has been used in humans for over 50 years. In low doses, it is effective in treating depression by blocking the NMDA glutamate receptor. It has a more rapid effect in alleviating symptoms, sometimes within hours, compared to more standard medications such as SSRIs which can take many weeks to months to begin to take effect.