Hallucinogens, such as LSD or “acid,” can cause unpredictable psychological effects, including delusions and visual hallucinations. Physical effects can include dangerously increased body temperature, heart rate, and blood pressure. People taking acid can also experience sleeplessness and rapid, intense emotional swings. This experience, as you might expect, can be extremely confusing and frightening to the person taking the drug. LSD is usually created in someone’s home laboratory, so it could contain many other ingredients that could even be deadly. Find more information on acid and LSD.