LSD stays in your system about 10.4 to 13.0 hours after you’ve taken it.
However, a possible adverse effect of acid use is Hallucinogen Persisting Perception Disorder (HPPD). A side effect like HPPD can appear after only a single use or after long-term use of LSD. It can last for days, weeks, or even months.
HPPD involves visual distortions such as flashes of light, positive afterimages, false movement in the peripherals, outright hallucinations, objects appearing larger or smaller than they actually are, and even geometric disturbances.[13] HPPD can require psychotherapy to improve a user’s symptomology.