How Aspirin Causes Ulcers
Aspirin, an NSAID, inhibits cyclooxygenase (COX) enzymes, blocking prostaglandin production. Prostaglandins normally protect the stomach lining by promoting mucus and bicarbonate secretion, maintaining blood flow, and suppressing acid. Without them, the mucosa erodes, leading to ulcers, especially at doses over 325 mg daily or with long-term use.[1][2]
How Low-Dose Aspirin Reduces Ulcer Risk
Low doses (81-325 mg) minimize systemic COX inhibition in the stomach while still providing cardiovascular benefits. This preserves enough prostaglandin activity for mucosal protection. Studies show ulcer incidence drops from 15-30% on high-dose to under 5% on low-dose regimens.[3][4]
Role of Enteric Coating and Buffering
Enteric-coated aspirin dissolves in the intestine, not stomach, reducing direct mucosal contact. Buffered versions (with calcium carbonate or magnesium oxide) neutralize gastric acid on contact. These cut ulcer risk by 50-75% versus plain aspirin, per endoscopic trials.[2][5]
Proton Pump Inhibitors (PPIs) for Added Protection
PPIs like omeprazole pair with aspirin to block acid pumps, restoring the pH barrier. Guidelines recommend PPIs for high-risk patients (age >60, prior ulcers, Helicobacter pylori infection, or steroids/NSAIDs combo). Trials confirm 80-90% risk reduction when combined.[1][6]
Who Needs Ulcer Prevention Most
Risk factors amplify aspirin's harm: age over 65, smoking, alcohol, H. pylori, or concurrent anticoagulants. Low-risk users often skip protection; high-risk test for H. pylori first and use PPIs.[4][7]
Misoprostol as an Alternative Protector
This prostaglandin analog replaces what aspirin blocks, cutting ulcers by 40-60%. It's effective but causes diarrhea in 20-30% of users, limiting use versus PPIs.[2]
[1]: NIH - Aspirin and GI Risks
[2]: NEJM - Prevention of NSAID-Induced Ulcers
[3]: AHA Guidelines on Low-Dose Aspirin
[4]: Lancet - Low-Dose Aspirin Ulcer Rates
[5]: Gastroenterology - Enteric-Coated Aspirin Trials
[6]: ACG Guidelines - NSAID Gastropathy
[7]: UpToDate - Aspirin Ulcer Prevention