Which is the most potent hallucinogen?

• A. Marijuana
• B. Phencyclidine
• C. Lysergic acid diethylamide
• D. Mescaline

Answer: (C)

Potency here means how little of the substance is needed to produce noticeable hallucinogenic effects. Among the options, LSD stands out because only very tiny amounts cause strong perceptual changes—typically in the tens of micrograms. That ultra-small effective dose makes LSD far more potent than the others listed. Mescaline needs hundreds of milligrams to achieve similar effects; marijuana’s changes come mainly from cannabinoids and aren’t classic hallucinogenic effects at typical doses; PCP can produce powerful psychoactive effects but acts as a dissociative rather than a pure hallucinogen and is active at higher, milligram-range doses. So the substance that requires the smallest dose to produce hallucinogenic experiences is LSD.