While ketamine — or Special K — is better known as a hallucinogen, scientists at Yale, Mount Sinai, and the National Institute of Mental Health think it could be an effective treatment for depression, particularly for "people who are not helped by widely used conventional antidepressants like Prozac or Lexapro," according to The New York Times:
And the depression seems to melt away within hours, rather than the weeks typically required for a conventional antidepressant. [The New York Times]
However, other scientists say more research needs to be done on the long-term effects of regular ketamine use. Doctors are reportedly already prescribing ketamine for depression (they can do this because it has long been used as an anesthetic), and charging up to $1,000 per treatment.