Overview
Aspirin is a widely used medication with analgesic, antipyretic, and anti-inflammatory properties. At low doses, it is frequently prescribed as an antiplatelet agent to prevent heart attacks and strokes.

Mechanism of Action
It irreversibly inhibits the cyclooxygenase (COX-1 and COX-2) enzymes. Low-dose aspirin selectively inhibits COX-1 in platelets, preventing the formation of thromboxane A2 and thereby inhibiting platelet aggregation for the lifespan of the platelet.

Dosage and Administration
For cardiovascular prevention, the typical low dose is 75 mg to 100 mg once daily. For pain or fever, doses of 300 mg to 600 mg every 4 to 6 hours are used, up to a maximum of 4 grams per day.

Side Effects
Gastrointestinal irritation, ulcers, and bleeding are common risks. It can also cause tinnitus (ringing in the ears) at high doses and allergic reactions, including aspirin-exacerbated respiratory disease.

Contraindications
Contraindicated in patients with active peptic ulcers, hemophilia, or other bleeding disorders. It should not be given to children under 16 years of age for viral infections due to the risk of Reye’s syndrome.

Pregnancy and Lactation
Low-dose aspirin may be used in pregnancy for specific indications (e.g., preeclampsia prevention). High doses should be avoided, especially in the third trimester. Use with caution during breastfeeding.