If you’re wondering why you sweat when you’ve got a fever you’ve come to the right place! It feels bad to have a fever, and fever sweating makes an uncomfortable experience even worse - but it’s for a good reason.

Why the Body Sweats

The main reason the human body sweats is critical for survival - to keep its internal temperature regulated. The process that allows the body to keep its internal temperature controlled is called thermoregulation. This helps to explain why people experience fever sweating.[1]

The body has many ways to heat itself up, but when it comes to cooling down its internal temperature the body only has one recourse - sweating. The only other way people can cool their body down is by using cooling behaviors like wearing less clothing, seeking cooler environments, and drinking or bathing in cool water.This makes sweating necessary for thermoregulation.[1]

In fact, sweating can release heat from the body at a rate that is more than ten times higher than a resting body can heat itself up.[2] This just means that sweating is a powerful tool the body uses to quickly get rid of heat and maintain a regular temperature.

This comes into play when a person gets sick because a fever raises the body’s internal temperature and the body sweats to cool itself back down.

Fever Sweating

A healthy person’s body tries to maintain a temperature around 98.6 degrees, although their temperature naturally fluctuates a little throughout the day (usually by .9 degrees).[3] However, this changes when a person develops a fever.

Humans usually develop a fever in response to infection, inflammation, or trauma. Fever can be defined as an adaptive response of the body to infection (or inflammation) in which the body increases its internal temperature above the usual 98.6 degrees. You can tell if you have a fever if your temperature is consistently higher than your normal or above 100.4 degrees. The body often uses fever as a tool to kill off foreign infections, but that is not always the case.[1]

Once a person’s body starts the fever process it releases chemical messengers called pyrogens into the bloodstream. Pyrogens are part of the immune system and, through a complex chemical process, cause a person’s body to raise in temperature.[1]

Once a person has a fever they will often experience symptoms like headache, malaise, lack of appetite, and other sickness behaviours. A person with a fever will also experience heat generating mechanisms like skin vasoconstriction (blood vessels constricting) which leads to chills and goosebumps, shivering, and a desire to be warm.[1]

Once a person’s fever runs its course, the body needs to lower its core temperature. Cue fever sweating. Sweating is the body’s only way to cool down so people who are recovering from a fever often experience sweating as a part of that process.[1]

Fever sweating may not be fun - but it’s actually a healthy response your body has to take care of itself.

Other Situations

Excessive sweating that isn’t related to primary hyperhidrosis or fever (due to an infection or injury) can be a sign of something more serious. At this point it probably isn’t just ordinary fever sweating. Certain diseases and conditions can cause secondary hyperhidrosis. Secondary hyperhidrosis is excessive sweating that is caused by an underlying issue. Some medications can also cause secondary hyperhidrosis.[4] It is wise to seek medical assistance if you suspect that you may have secondary hyperhidrosis, a high or long-term fever, or experience excessive sweating accompanied by pallor and diaphoresis.

  1. Ogoina, D. (2011). Fever, fever patterns and diseases called ‘fever’ – A review. Journal of Infection and Public Health, 4(3), 108-124. doi:10.1016/j.jiph.2011.05.002 Retrieved from https://pubmed.ncbi.nlm.nih.gov/21843857/
  2. Schmidt, K. D., & Chan, C. W. (1992). Thermoregulation and Fever in Normal Persons and in Those With Spinal Cord Injuries. Mayo Clinic Proceedings, 67(5), 469-475. doi:10.1016/S0025-6196(12)60394-2 Retrieved from https://www.mayoclinicproceedings.org/article/S0025-6196(12)60394-2/fulltext
  3. Del Bene, V. E. (1990). Temperature. Clinical Methods: The History, Physical, and Laboratory Examinations. Retrieved March 3, 2019, from https://www.ncbi.nlm.nih.gov/books/NBK331/
  4. Pariser, D. M. (2014). Hyperhidrosis (4th ed., Vol. 32). Amsterdam: Elsevier Pub. Co., 2014. Retrieved from https://www.elsevier.com/books/hyperhidrosis-an-issue-of-dermatologic-clinics/pariser/978-0-323-32607-0