LSD

LSD (lysergic acid diethylamide) is one of the most potent mind-altering substances known, active at microgram doses. First synthesized in 1938 and famous from the 1960s, it is usually sold as drops on small squares of blotter paper, as tiny tablets ("microdots"), or in liquid form. It produces profound changes in perception, mood, and thought — "trips" — that typically begin within 20 to 90 minutes and can last 12 hours or more. LSD is not addictive the way opioids or stimulants are, and it rarely causes fatal poisoning, but its effects are intense and unpredictable, and the main risks are psychological: frightening experiences, impaired judgment that can lead to accidents, and, in a small number of people, lasting perceptual or psychiatric effects. There is renewed scientific interest in psychedelics' therapeutic potential, but that research happens in tightly controlled medical settings, not the unregulated market.

LSD acts mainly on serotonin signaling, binding strongly to the 5-HT2A receptor in regions of the brain involved in perception, mood, and cognition. By altering this serotonin activity, LSD disrupts the brain's normal filtering and integration of sensory information, producing the visual distortions, altered sense of time, and shifts in thought and emotion that characterize a trip. Because the body quickly builds tolerance — the same dose has much less effect over consecutive days — taking more to recapture the effect is both ineffective and dangerous. The drug does not produce the compulsive, withdrawal-driven use seen with physically addictive drugs, but psychological reliance and problematic use can still occur.

An LSD experience varies enormously with dose, the person's mindset, and their surroundings. Common effects include vivid visual distortions (intensified colors, moving or geometric patterns), a blurring of the senses, an altered sense of time and self, and powerful emotional shifts that can swing between euphoria and anxiety. Physical effects include dilated pupils, raised heart rate and blood pressure, sweating, dizziness, and loss of appetite. A difficult experience — a "bad trip" — can involve intense fear, paranoia, panic, and distressing thoughts, and impaired judgment during a trip can lead to dangerous behavior or accidents. Effects can persist for many hours, and some people feel emotionally drained afterward.

LSD's risks are overwhelmingly psychological rather than toxic — fatal overdose from LSD itself is extraordinarily rare. The most common acute danger is a bad trip: overwhelming fear, paranoia, or panic that, combined with impaired judgment and an altered sense of reality, can lead to accidents or risky behavior. People with a personal or family history of psychosis or serious mental illness face a higher risk of triggering a lasting psychiatric reaction. Two rare but recognized long-term effects are persistent psychosis and hallucinogen persisting perception disorder (HPPD), in which visual disturbances or "flashbacks" recur after the drug has worn off. Because there is no quality control in the illicit market, the dose on a given blotter is unknown, and substances sold as LSD are sometimes other, more dangerous chemicals (such as certain NBOMe compounds) that can be toxic. There is no medication that reverses LSD; a difficult experience is managed with calm reassurance and a safe environment, and severe agitation, injury, or medical symptoms warrant emergency care. For poisoning guidance call Poison Control at 1-800-222-1222; for substance-use or mental-health support the SAMHSA National Helpline is 1-800-662-4357.

heightened sensory awareness, visual distortion (size/shape/color), "hearing colors," intensified emotions, mood swings, time distortion, depersonalization

30–60 min

10–12 hr

fatigue/anxiety/depression 12–24 hr

"bad trip" (anxiety/panic/confusion/combative); dilated pupils, raised temp/HR/BP, sweating, tremors

none in US

NFLIS >51,000 reports since 1997 (peak 4,865 in 2020 → 1,588 in 2024); NSDUH ~30.9M lifetime (2024)