LSD flashbacks can be spurred by use of drugs such as marijuana. Preliminary evidence suggests serotonin reuptake inhibitors like Prozac and Zoloft may also exacerbate the LSD flashback syndrome.
Aghajanian, G. K. and G. J. Marek. "Serotonin and Hallucinogens." Neuropsychopharmacology (1999): 16S-23S
Markel, H., A. Lee, R. Holmes, and E. Domino. "LSD Flashback Syndrome Exacerbated By Selective Serotonin Reuptake Inhibitor Antidepressants In Adolescents." Journal of Pediatrics (November 1994): 817-819.
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