Many designer drugs, including LSD, psilocybin, and mescaline, are hallucinogenic drugs that produce altered sensations, perceptions, thoughts, and emotions. Hallucinogen intoxication results in stimulation effects such as tachyardia, pupillary dilation, and tremors, then visual illusions and possibly hallucinations (typically visual but sometimes auditory or tactile). Hallucinogen intoxication can also result in depression, paranoia, impaired judgement, perceptual changes, and difficulty functioning in social or occupational settings.

MDMA (also known as Ecstasy) is a hallucinogen that leads to a higher-rate of motor activity, general arousal, and a dreamy condition with accompanying delusions and hallucinations. Frequent use of MDMA can result in hypothermia and dehydration.

Other hallucinogens include:

1. PCP
2. Peyote (a cactus found in Texas and Mexico)
3. DXM (found in cough medications)
4. Ketamine ("Special K", "Cat Valium", and "K")