How does aspirin reduce inflammation?
Aspirin (acetylsalicylic acid) is an anti-inflammatory drug largely because it lowers production of inflammatory chemicals called prostaglandins. It does this by irreversibly inhibiting the cyclooxygenase (COX) enzymes—COX-1 and COX-2—which normally help make prostaglandins from arachidonic acid. With COX activity reduced, fewer prostaglandins are formed, which decreases inflammation, pain, and fever.
What exactly does aspirin inhibit in the inflammation pathway?
Inflammation involves release of arachidonic acid from cell membrane phospholipids. COX enzymes convert arachidonic acid into prostaglandins (and related mediators). Aspirin works upstream by blocking COX enzymes through irreversible acetylation, so affected cells can’t resume prostaglandin synthesis until new COX enzymes are made.
Why is aspirin called “irreversible”?
A key feature is that aspirin acetylates COX in a way that permanently inactivates the enzyme’s activity. This is why aspirin’s effects can last longer than its presence in the bloodstream for some actions: the enzyme is “turned off” rather than just temporarily inhibited.
How is aspirin’s anti-inflammatory effect related to pain relief and fever?
The same prostaglandin reduction that drives anti-inflammatory effects also contributes to pain and fever relief. Prostaglandins sensitize pain pathways and affect temperature regulation in the hypothalamus, so lowering them reduces both pain and fever.
Does aspirin also affect blood clotting that can influence inflammation?
Yes. By inhibiting COX-1, aspirin reduces thromboxane A2, which helps platelets clump and form clots. This can matter clinically because bleeding risk increases. While thromboxane reduction is mainly discussed for cardiovascular and clotting prevention, it is a downstream consequence of aspirin’s COX inhibition that patients may associate with “inflammation meds” in general.
What aspirin dose pattern matters for inflammation?
Anti-inflammatory (and pain/fever) effects generally require higher dosing than low-dose “aspirin” used for cardiovascular protection. Dose determines how much COX activity is suppressed and which tissues/mediators are most impacted, though exact dosing schedules depend on the condition and patient factors.
What side effects can come from blocking prostaglandins?
Because prostaglandins also protect the stomach lining and support kidney function, COX inhibition can lead to gastric irritation and ulcer risk. Prostaglandin reduction can also contribute to kidney stress in vulnerable patients. Aspirin can also increase bleeding tendency due to its platelet COX-1 effects.
Are there alternatives if someone can’t take aspirin?
Other nonsteroidal anti-inflammatory drugs (NSAIDs) also reduce inflammation by lowering prostaglandins via COX inhibition, but they differ in selectivity (COX-2 vs COX-1) and whether they act irreversibly or reversibly. That can change bleeding risk, stomach risk, and onset/duration.