Health effects

Short-term effects
Using greater amounts of ketamine can cause muscle rigidity, headaches, nausea, confusion and disorientation, twitching, slurred speech, blurred vision and hallucinations.

The comedown can leave the user feeling muscle aches and a reluctance to physically exert themselves.

Because ketamine takes someone 'inside their own head', a user's mental state can be affected. There is a risk of making negative mental states worse. Depression or paranoia, can remain even after the trip wears off.

Long-term effects
Little is known about the long-term effects of ketamine, although there are some reports of LSD-type flashbacks and a negative effect on short term memory.