LSA is a naturally occuring psychedelic chemical with a potency 1/10 to 1/30th that of LSD. It has some similarities in effect to LSD, but is generally considered much less stimulating and can be sedating. Structurally LSA and LSD are quite similar.

Dosage of LSA is not well established since few have experimented with the pure chemical and recorded their experiences publicly. Albert Hofmann tried an I.M. injection of 500 micrograms of LSA and found the effects medium-strong. Hofmann later reports the active oral dose of LSA at "2 to 5 milligrams".

"Hofmann first established [LSA's] effect in 1947, 13 years before it was known to be the active principle in ololiuhqui... He showed that the drug was active at doses of 500 micrograms to 1 milligram. No entheogenic effect was noticed by Hofmann after taking 2 milligrams of isoergine, although sedative symptoms similar to ergine inebriation were prominent. Hofmann's description of perceiving the 'unreality and complete meaninglessness of the outside world' after taking 2 millgrams of isoergine (Hofmann 1963a), however, sounds like the paradoxical depressent effect experienced commonly with the threshold doses of psilocybine and other entheogens and it is possible that isoergine is entheogenic at higher doses." (Ott Pharmacotheon 1993, pg. 128)