Diarrhea

Diarrhea is the rapid, loose, or liquid evacuation of the bowel arising as a direct consequence of psychoactive substance use.

As a drug effect it is acute and dose-proportional, easing as the substance clears the system rather than persisting as a standing gastrointestinal condition. It ranges from mild urgency and loose stool to repeated, cramping evacuation, and while it resolves without intervention in most cases, sustained episodes carry a real risk of dehydration and electrolyte loss.

It is an uncommon adverse effect across psychoactive substances. It is most commonly induced at moderate to high doses under psychedelics such as psilocybin mushrooms, 2C-B-FLY, and 2C-T-2, and under stimulants such as modafinil, 3-FEA, and MDPV. It also appears under depressants like baclofen and phenibut, and has been reported under cannabinoids such as cannabidiol.

Diarrhea is felt as a mounting internal pressure in the lower abdomen — a cramping urgency that demands immediate relief. Onset is often preceded by audible bowel sounds and a rolling, liquid discomfort deep in the gut. The urge can arrive abruptly, with little warning time.

After evacuation the pressure eases, but it frequently returns in waves over the course of the session. At higher doses, particularly under psychedelics, the cramping can be sharp enough to dominate the experience, distracting from or intensifying other concurrent effects.

Diarrhea arises through different pathways depending on the drug class:

• Psychedelics — act on serotonin receptors throughout the enteric nervous system, accelerating gut motility and triggering secretory activity in the intestinal lining.
• Stimulants — elevate sympathetic tone and accelerate gastrointestinal transit, reducing the time available for fluid absorption in the colon.
• Depressants — certain compounds in this class alter gut motility or directly irritate the gastrointestinal tract through their receptor targets.
• Cannabinoids — cannabidiol modulates gut motility through peripheral cannabinoid receptors, producing loose stool in susceptible individuals.

How much each pathway contributes in a given case is not fully understood.

Who experiences it, and how severely, varies widely. Higher doses raise both likelihood and intensity across all implicated classes. Prior gastrointestinal sensitivity or an irritable bowel predisposition makes it substantially more likely. Consuming a substance on a full stomach can amplify gut reactivity; an empty stomach sometimes accelerates onset.

Anticipatory anxiety about gut effects tends to be self-fulfilling — stress alone is sufficient to prime intestinal motility. Eating lightly and staying well hydrated before a session tends to reduce severity.