Does Caffeine Decrease Body Temperature? Debunking the Myth

November 29, 2025 •

4 min read

Research shows caffeine is a powerful central nervous system stimulant that triggers metabolic responses, a process known as thermogenesis. This initial effect raises the body's internal temperature, which contradicts the common question: does caffeine decrease body temperature?.

Quick Summary

Caffeine typically causes a slight, temporary increase in core body temperature by boosting metabolic rate. It does not lower body heat, and any perceived cooling is often psychological or related to secondary effects like sweating at high doses.

Key Points

Caffeine Increases Body Temperature: Far from lowering it, caffeine acts as a thermogenic agent, causing a slight rise in core body temperature.
Metabolic Boost is the Cause: The temperature increase is driven by caffeine's stimulation of the central nervous system, which increases metabolic rate.
Vasoconstriction Retains Heat: Caffeine can cause peripheral blood vessels to narrow, reducing heat loss through the skin and further contributing to a rise in internal temperature.
'Feeling Colder' is Often Psychological: Any cool sensation from an iced coffee is mostly subjective and temporary, as the body's core temperature is still affected by caffeine's thermogenic properties.
Individual Factors Matter: The magnitude of caffeine's effect on body temperature varies based on dosage, personal tolerance, and individual metabolism.
Avoid During Fever: Drinking caffeinated beverages while sick with a fever can worsen dehydration due to its diuretic effects, hindering recovery.
High Doses Can Cause Sweating: Excessive caffeine intake can lead to stress-related sweating, but this is the body's response to an increased internal temperature, not a sign of cooling.

The Surprising Truth About Caffeine and Thermoregulation

When most people think of caffeine's effects, they focus on increased energy and alertness. The relationship between caffeine and body temperature, however, is more nuanced and often misunderstood. Far from lowering your internal temperature, scientific evidence overwhelmingly points to caffeine causing a slight but measurable increase. This phenomenon is a direct result of how caffeine interacts with the body's metabolic and nervous systems.

The Mechanism: Thermogenesis and Metabolic Boost

Caffeine's role as a thermogenic agent is key to understanding its effect on body heat. By stimulating the central nervous system, caffeine prompts an increase in metabolic rate—the speed at which your body burns calories for energy. This process generates heat as a byproduct. The effect is typically modest and peaks within 30 to 60 minutes after consumption, contributing to a slight rise in core body temperature. This metabolic boost is also why caffeine is sometimes included in weight-loss supplements, as it can slightly increase calorie expenditure.

Sympathetic Nervous System and Stress Hormones

The central nervous system stimulation caused by caffeine also triggers the release of stress hormones, including adrenaline and cortisol. This 'fight or flight' response can lead to an increased heart rate, elevated blood pressure, and a heightened state of alertness. These physiological changes can collectively contribute to a feeling of being warmer or even cause anxiety-related sweating, which can be mistaken for an attempt by the body to cool down. While sweating is a cooling mechanism, the underlying cause is an increase in internal heat production driven by caffeine.

Vascular Effects: Vasoconstriction and Blood Flow

Caffeine's influence on blood vessels can also play a complex role in temperature regulation. While it can cause some vasodilation (widening of blood vessels), especially in the brain, it is also known to cause peripheral vasoconstriction (narrowing) in the skin. This effect reduces blood flow to the skin, limiting the body's ability to dissipate heat. By trapping more heat inside the body, this vasoconstriction can also contribute to a rise in core body temperature.

The Illusion of Cold: How Temperature and Feeling Intersect

Experiencing a cold sensation after drinking an iced coffee is more a psychological effect than a physiological one. The coldness of the beverage provides a momentary, localized cooling effect to the mouth and throat, offering subjective relief in hot weather. However, once absorbed by the body, the overall impact on core temperature is minimal and often outweighed by the thermogenic effect of the caffeine itself. Therefore, consuming a cold beverage with caffeine does not cancel out the stimulant's warming properties.

Factors Influencing the Effect on Body Temperature

The degree to which caffeine affects an individual's body temperature depends on several factors:

Dosage: Higher doses of caffeine typically produce a more pronounced thermogenic and metabolic effect. Very high doses can also lead to more disruptive side effects like excessive sweating and jitters.
Individual Tolerance: Regular caffeine consumers develop a tolerance over time, which may lessen the impact on metabolism and body temperature compared to someone who is not used to it.
Individual Metabolism: Genetic factors and overall health can influence how quickly and efficiently an individual metabolizes caffeine. People with a lower BMI, for instance, have shown larger metabolic increases from caffeine.
Activity Level: Combining caffeine with exercise, especially in a hot environment, can further increase core body temperature and potentially disrupt thermoregulation.

Common Caffeine Myths vs. Scientific Reality


Aspect	Myth	Scientific Reality
Effect on Temperature	Caffeine actively cools the body down.	Caffeine typically causes a slight increase in core body temperature via thermogenesis.
Mechanism for Cooling	It somehow lowers the body's internal thermostat.	It stimulates metabolic processes that generate heat, and the body's attempt to cool down (sweating) is a response to this.
Best for Fevers	Drink coffee to help break a fever.	Not advised. Caffeine is a diuretic and can worsen dehydration, which is counterproductive when fighting a fever.
Iced vs. Hot Drinks	Iced coffee has a significant cooling effect.	The cooling is subjective and temporary. The thermogenic effect of caffeine is still present, and iced drinks do not significantly lower core temperature.

Conclusion

The idea that caffeine decreases body temperature is a common misconception. In reality, caffeine's role as a stimulant activates thermogenesis, a metabolic process that actually increases the body's heat production. While factors like drinking a cold beverage or experiencing high-dose sweating can create a feeling of cooling, these effects do not override the fundamental thermogenic response. For most healthy individuals, the temperature change is minimal, but understanding the actual physiological process can help manage caffeine intake, especially in specific situations like exercise or illness.

For more in-depth information on caffeine's vascular mechanisms, consult studies available via the National Institutes of Health.

Frequently Asked Questions

Yes, drinking coffee can cause your body temperature to rise slightly. The caffeine in coffee stimulates the central nervous system, boosting your metabolic rate and generating heat in a process called thermogenesis.

Caffeine does affect thermoregulation. It prompts the body to produce more internal heat and can also cause peripheral vasoconstriction, which can reduce heat loss, contributing to a small increase in core body temperature.

An iced coffee can provide a temporary, psychological feeling of coolness in your mouth and throat. However, the caffeine will still cause a metabolic boost that generates heat, so it is not an effective way to lower your core body temperature.

Caffeine can cause you to feel hot, flushed, or even anxious, which can result in sweating. These are reactions to the stimulant effect and increased metabolism, which are distinct from a fever or medical condition but are driven by a slight rise in actual core temperature.

It is not recommended to drink caffeine when you have a fever because caffeine acts as a diuretic, which can worsen dehydration. Staying hydrated is crucial for recovery when you are sick, so water is a much better choice.

People who regularly consume caffeine often develop a tolerance, meaning they may experience a less significant increase in body temperature compared to individuals who are sensitive or not accustomed to caffeine. Metabolism speed, which is partly genetic, also plays a role.

Yes, combining caffeine with exercise, especially in hot conditions, can potentially worsen heat intolerance. It increases core temperature and can accelerate fluid loss through a mild diuretic effect, complicating the body's thermoregulatory response.