Have you ever wondered how aspirin reduces fever? To understand the answer to this question, we need to take a closer look at the biological mechanisms that cause fever in the first place.

When our body detects an infection, it responds by producing pyrogens, which are substances that signal the immune system to raise the body's temperature in order to fight off the infection. (1) Pyrogens increase the production of interleukin-1 in phagocytic cells. (2) IL-1 then acts on the anterior hypothalamus, a part of the brain that controls body temperature, to increase the production of prostaglandins. Prostaglandins increase the set-point temperature, which in turn sets in motion the heat-generating mechanisms that increase body temperature and produce fever. (3)

Aspirin works by inhibiting cyclooxygenase, an enzyme that is necessary for the production of prostaglandins. By inhibiting cyclooxygenase, aspirin reduces the production of prostaglandins and, in turn, lowers the set-point temperature, which reduces fever. (4)

It's important to note that fever is a natural response to infection, and it actually serves an important purpose in the body's immune response. Fever stimulates the immune system, enhances the activity of white blood cells, and inhibits the growth of certain viruses and bacteria. In fact, some researchers believe that fever may even help to prevent the spread of infection by making it less hospitable for pathogens to thrive in our body. (5, 6)

So while aspirin may be effective at reducing fever, it's important to remember that fever itself is a powerful tool that our body uses to fight off infection. As always, it's best to consult with a healthcare provider before taking any medication to treat fever or other symptoms of illness.

Resources:

1. El-Radhi AS. Pathogenesis of Fever. Clinical Manual of Fever in Children. 2019 Jan 2:53–68. doi: 10.1007/978-3-319-92336-9_3. PMCID: PMC7122269.
2. Dinarello CA. The history of fever, leukocytic pyrogen and interleukin-1. Temperature (Austin). 2015 Apr 14;2(1):8-16. doi: 10.1080/23328940.2015.1017086. PMID: 27226996; PMCID: PMC4843879.
3. Tabarean IV, Behrens MM, Bartfai T, Korn H. Prostaglandin E2-increased thermosensitivity of anterior hypothalamic neurons is associated with depressed inhibition. Proc Natl Acad Sci U S A. 2004 Feb 24;101(8):2590-5. doi: 10.1073/pnas.0308718101. PMID: 14983053; PMCID: PMC356994.
4. Wu KK. Aspirin and other cyclooxygenase inhibitors: new therapeutic insights. Semin Vasc Med. 2003 May;3(2):107-12. doi: 10.1055/s-2003-40668. PMID: 15199473.
5. Evans SS, Repasky EA, Fisher DT. Fever and the thermal regulation of immunity: the immune system feels the heat. Nat Rev Immunol. 2015 Jun;15(6):335-49. doi: 10.1038/nri3843. Epub 2015 May 15. PMID: 25976513; PMCID: PMC4786079.
6. Wrotek S, LeGrand EK, Dzialuk A, Alcock J. Let fever do its job: The meaning of fever in the pandemic era. Evol Med Public Health. 2020 Nov 23;9(1):26-35. doi: 10.1093/emph/eoaa044. PMID: 33738101; PMCID: PMC7717216.