Body temperature

Body temperature refers to the heat level the body maintains through a continuous regulatory process called thermoregulation. A healthy core temperature sits around 37 °C (98.6 °F), though it varies slightly with time of day, age, and where it is measured.

It is tracked as a vital sign because both hyperthermia (dangerously elevated temperature) and hypothermia (dangerously low temperature) indicate that this regulatory control is breaking down. Even modest deviations from the normal range compromise enzyme function, and extreme deviations can become life-threatening.

How it works · its role

Thermoregulation is coordinated by the hypothalamus, a small region at the base of the brain that acts as the body's thermostat. When core temperature rises, it triggers vasodilation near the skin surface and activates sweat glands to shed heat. When temperature falls, it signals vasoconstriction and shivering to conserve and generate warmth.

The hypothalamus integrates signals from temperature-sensitive neurons distributed across the body and skin. During infection, pyrogens — signalling molecules released by immune cells — can deliberately raise the set point, producing a fever as part of the immune response rather than as a failure of regulation.

Relevance to substances & effects

Many psychoactive substances disrupt thermoregulation, and several do so in ways that carry meaningful risk.

Stimulants — including amphetamines, cocaine, and MDMA — tend to raise body temperature by increasing metabolic rate, driving muscle activity, and sometimes impairing sweating. MDMA carries a particularly well-documented hyperthermia risk, which is compounded in warm environments with sustained physical activity. Because serotonin is involved in hypothalamic temperature control, serotonergic substances can push temperature higher than the body would otherwise allow.

Depressants and opioids generally lower core temperature by suppressing metabolic activity and promoting vasodilation. Alcohol produces a misleading sensation of warmth through peripheral vasodilation while actually accelerating heat loss to the environment — a hazard in cold conditions that is easy to underestimate.

Dissociatives such as ketamine can blunt awareness of temperature discomfort without fully disabling thermoregulation, making it harder to notice that the body is in distress. Across all of these substance classes, the interaction between the drug, the environment, and exertion level shapes the actual risk as much as the substance itself does.