D-lysergic acid diethylamide (LSD, acid, blotter) belongs to a group of drugs known as hallucinogens. Like other hallucinogens produces images, sounds, and other sensations that may seem real to users during the period of intoxication but are actually figments of their own imaginations. Effective doses of LSD are often exceedingly small—on the order of millionths of a gram. Though the profound perceptual changes that LSD brings about may place the user at risk of indirect bodily harm or injury, in most cases of mild to moderate intake the long-term effects of LSD involve the brain and psyche rather than the body.

Long-term LSD use results in a demonstrable tolerance phenomenon. As a result, long-term and heavy users of LSD users may require large doses of the drug to elicit the desired effects. This can be dangerous, as LSD doses of more than 400 mcg have been reported to result in life-threatening toxicity. This dangerous situation may comprise:
• Hyperthermia, or overheating.
• Cardiovascular collapse, or sudden heart failure.
• Death or severe injury due to impaired judgement while intoxicated.
These physical signs of LSD use are in addition to everything from having anxiety attacks while using the drug and even after its use, to paranoia and a general lack of motivation and cognitive function. Also, if someone has what’s called a bad trip, they may exhibit incoherent speech and even seizures. In the short-term, the effects of LSD are usually felt around 30 to 45 minutes after the person takes the drug, and the trip or high can last anywhere from six to eight hours on average.

LSD isn’t considered to be a physically addictive drug. And in general, you won’t experience physical withdrawal symptoms when you stop taking LSD. But the development of physical tolerance to LSD, however, is possible. Developing more tolerance means that you’ll need to take larger doses of the drug to achieve the same hallucinogenic effects. By taking LSD, you may also build up a cross-tolerance to other hallucinogenic drugs, such as mescaline. usually decreases within a few days after you stop taking LSD. Although LSD may not produce physical withdrawal symptoms, you may become psychologically dependent on hallucinogenic drugs if you take them on a regular basis. Some long-term users experience anxiety, depression, or irritability if they don’t have access to LSD or other hallucinogens. The long-term physical side effects of LSD use are still being investigated.