They can also cause death by disrupting the brain's control of the heart and respiration. Other stimulant and amphetamine use can have the same effect as cocaine and cause increased heart rate and blood pressure that can result in a stroke or heart failure. Symptoms include dizziness, sleeplessness, and anxiety. Use can also lead to psychosis, hallucinations, paranoia, and even physical collapse. Depressants and barbiturates can cause physical and psychological dependence that can lead to respiratory depression, coma and death, especially when used in concert with alcohol.
Withdrawal can lead to restlessness, insomnia, convulsions, and even death.
LSD, PCP, mescaline, and peyote are classified as hallucinogens. Hallucinogens interrupt the brain messages that control the intellect and keep instincts in check. Large doses can produce convulsions and coma, heart and lung failure. Users complain of persistent memory problems, speech difficulties, and flashbacks . Because these drugs stop the brain's pain sensors, drug experiences may result in severe self-inflicted injuries.