Drugs of this type include lysergic acid diethylamide (LSD, “acid”), psilocybin (”magic mushrooms”) and mescaline (peyote). Drugs of the LSD-type induce a state of excitation of the brain that is manifested in a number of ways:

1. - changes in mood
2. - anxiety
3. - distortion in sensory perception
4. - visual hallucinations
5. - delusions
6. - depersonalization
7. - dilation of the pupils
8. - increase in body temperature
9. - rise in blood pressure.

Psychological dependence of drugs of the hallucinogen-type varies greatly, but it is usually not intense. The users may enjoy the effects of these agents and may wish to repeat them, but if such agents are not readily available, these persons will either do without them or accept a substitute. A minority of users may develop strong psychological dependence on these substances. No evidence of physical dependence has been detected when the drugs are withdrawn abruptly. A high degree of tolerance to LSD and to psilocybin develops rapidly and disappears with equal rapidity. Tolerance to mescaline develops more slowly.
Persons who are tolerant to anyone of these drugs will find they are tolerant to the other two. The chief dangers to the individual arise from the psychological effects of hallucinogens. Serious impairment of judgement has led to dangerous decisions and accidents, while a “bad trip” with an associated panic reaction can be a most frightening experience.