Headache

body effect

valenceadversefrequencycommontemporalaftereffect

AI-inferred — this entry was drafted by AI and has not yet been verified against primary sources. A sourced revision is planned.

Headache is a pain or pressure felt in the head, scalp, or neck that arises during or after psychoactive substance use.

As a drug effect it is acute and dose-proportional, easing as the substance wears off or in the hours that follow; this sets it apart from a standing headache disorder. It ranges from a dull background ache to a severe, throbbing pain that impairs concentration and comfort.

It is one of the most commonly reported somatic effects across psychoactive substances and typically presents as an aftereffect. It most often appears at moderate to high doses under psychedelics such as LSD, psilocybin mushrooms, and 25B-NBOH, and under stimulants such as MDMA, modafinil, and cocaine; it also emerges as a rebound from depressants like alcohol, GHB, and baclofen, and is reported under nootropics including 5-hydroxytryptophan, galantamine, and meclofenoxate.

phenomenology

Headache is felt as a persistent ache, pressure, or throbbing localized to the temples, forehead, or the base of the skull: attention is pulled inward toward the pain, concentration fragments, and sensitivity to light or sound often amplifies the experience.

It commonly comes with neck tension, a heaviness behind the eyes, and general fatigue. Attending closely to the pain tends to make it feel worse. At higher doses, particularly under stimulants, the throbbing becomes pulsatile and difficult to ignore, disrupting any sustained mental activity.

mechanism

Headache arises through different pathways depending on the drug class:

Psychedelics — serotonergic and vasoactive changes are thought to contribute; pain often peaks in the hours after the experience, reflecting demands placed on cerebrovascular regulation.
Stimulants — drive vasoconstriction during the active phase; compensatory vasodilation as the substance wears off, compounded by dehydration and jaw tension, produces a rebound headache.
Depressants — vasodilation, dehydration, and metabolic byproducts contribute to the characteristic aftereffect.
Nootropics — mechanisms vary; cholinergic and serotonergic activity have both been implicated depending on the compound.

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

safety

Headache is not dangerous in itself, but certain patterns warrant attention.

If it happens — rest in a quiet, low-light space, drink water, and allow the substance to wear off before taking any over-the-counter analgesic.
Seek help if — the pain arrives suddenly at full intensity, or is accompanied by confusion, vision changes, vomiting, neck stiffness, or fever; these can indicate something beyond an ordinary substance-related headache.
Higher risk — people with a history of migraines or vascular conditions should treat any severe headache appearing under stimulants or psychedelics as a signal to reduce stimulation and seek care if the pain does not ease promptly.

variability

Who experiences it, and how strongly, varies widely. Higher doses raise both likelihood and severity. Dehydration and poor sleep entering a session — especially under stimulants and depressants — strongly predispose toward it, and those with a history of migraines tend to experience it more intensely.

Expecting a headache can lower the threshold at which it becomes intrusive. Staying well hydrated, getting adequate rest, and keeping doses moderate substantially reduces its incidence.