What It Is:

LSD (lysergic acid diethylamide) is a hallucinogenic drug. Hallucinogens change the way people sense the world around them.

Sometimes Called:

acid, sugar cubes, white lightning, dose, tripping, blotter

How It's Used:

LSD is odorless, colorless, and tasteless. It can be painted onto small squares of paper that people lick or swallow.

What It Does:

LSD causes the senses of space, distance, and time to become altered. People say they "hear" colors or "see" sounds, and have strange feelings and strong emotions.

Many users refer to an "acid trip" — when the effects don't let up and can last for up to 12 hours at a time. LSD also can cause "bad trips" — when users experience panic, confusion, sadness, and scary images. Bad reactions can happen with the first use and a user may have flashbacks later, experiencing the feelings of a bad trip even after the drug wears off.

Because LSD also affects judgment and behavior, users might find themselves in a dangerous situation.

Physical changes include increased heart rate and blood pressure, muscle twitches and shaking, dilated pupils, sweating, sleeplessness, and loss of appetite.