How does aspirin reduce fever? Anti-pyretic action of aspirin:
Aspirin is an NSAID (Non-steroidal anti-inflammatory drug). All NSAIDs inhibits the cycloxygenase (COX-1 and COX-2) enzyme (by irreversible non-competetive inhibition) which is required for the synthesis of prostaglandin E2.
So, since no prostaglandin, particularly prostaglandin E2 in this case, is produced the temperature point in hypothalamus goes back to normal and thus the body temperature becomes normal again.
2. Aspirin also inhibits the migration of macrophages to the site of inflammation, thereby reducing the secretion of interleukin-1 by the macrophages.
Interleukin-1- a cytokine- is also responsible for fever. So aspirin prevetns migration of macrophages to the site of inflammation and indirectly inhibts the release of interleukin-1.
3. If however any interleukin-1 is produced by the macrophages that manages to go to the site of inflammation, aspirin has the ability to block the central nervous system response to the interleukin-1. So no fever occurs.
One important point to note is that Aspirin does not have any effect on the normal body temperature. That means aspiting will not lower the normal body temperature.
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