Like all anaesthetics, Ketamine is not a good mixer. Respiratory depressants like alcohol and valium are particularly risky. At anything above a low level dose (50mg or less), Ketamine is so powerful and complete that for most users, combining it with any other drug only detracts from the experience.

Please note: there have been very few scientific studies into the effects of combining psychoactive drugs. The information presented here is anecdotal. It is based on the subjective reports of experienced users. Different people will respond differently to different drugs and drug combination. Know your body.

alcohol don't - can cause nausea and vomiting; can also depress respiratory system at high doses

amphetamines some users add amphetamines to lower doses of Ketamine for a more MDMA/Cocaine psychedelic party drug feel

amyl nitrate Ketamine and poppers - what could be more gay?

cannabis K amplifies certain cannabis effects, notably closed-eye imagery; no reported problems, but make sure you stub it out before taking K

ecstasy (MDMA) some like to take small K 'bumps' towards the end of their E experience; brings back the Ecstasy sensations and adds a psychedelic tinge

heroin counters the psychedelic effects of K; depresses respiratory system so, as a rule, don't

LSD no reported health problems but can make a weird trip even weirder; increases K's ability to induce out of body experiences; some users report that small amounts can 'ground' the wilder aspects of LSD experience

magic mushrooms exactly what it says on the packet: simultaneous mushroom and ketamine feelings; time slow downs; no reported health problems

tobacco in a Ketamine daze you could burn your house down

valium don't; you can't be any more relaxed when you're on K; depressants are dangerous with Ketamine