LSD (lysergic acid diethylamide) is a synthetic chemical that is made from a substance found in ergot, which is a fungus that infects rye (grain) . It is a potent hallucinogen that can alter the way people experience the world, and it can impact ones mood, senses, and attention. LSD is considered a classic hallucinogen, along with psilocybin, ayahuasca, and mescaline. It is a mind-altering drug that acts on the brain and changes mood, behavior, and the way people relate to the world around them. LSD affects the action of a brain chemical called serotonin, which helps control behavior, mood, the senses, and thinking. LSD is usually taken orally, but it can also be inhaled through the nose or injected into a vein. LSD is available in saturated absorbent paper, tablets, or capsules, and it is usually taken by mouth. LSD is also sometimes sold as a liquid, in a tablet, or in capsules. LSD is a very strong hallucinogen, and only a tiny amount is needed to cause hallucinations. LSD users call their hallucinogenic experiences "trips," which can last for up to 12 hours at a time. LSD can cause "bad trips," which can include 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. LSD is illegal in the United States, and it is a Schedule I drug, which means it has no accepted medical use and a high potential for abuse.