Most Frequent Stomach Side Effects
Aspirin commonly irritates the stomach lining due to its direct contact and inhibition of protective prostaglandins. The top reported effects include heartburn, indigestion (dyspepsia), and nausea, affecting up to 25-50% of regular users in clinical studies.[1][2] Stomach pain or upper abdominal discomfort follows closely, often described as a burning sensation.
How Aspirin Causes These Issues
Aspirin blocks COX-1 enzymes, reducing mucus and bicarbonate production that shield the stomach. This exposes the lining to acid, leading to erosion. Enteric-coated versions delay release to minimize early irritation but don't fully prevent it.[1][3]
Risk of Ulcers and Bleeding
Chronic or high-dose use (over 325mg daily) raises ulcer risk by 2-4 times, with bleeding in 1-2% of users yearly. Symptoms start as mild pain but can progress to black stools (melena) or vomiting blood if erosions deepen.[2][4] Factors like age over 60, alcohol, smoking, or concurrent NSAIDs amplify this.
Who Gets Hit Hardest and Prevention Tips
Higher risks apply to those with prior ulcers, H. pylori infection, or using steroids/SSRIs. Take with food or milk, switch to low-dose (81mg) for heart protection, or opt for alternatives like acetaminophen for pain. PPIs (e.g., omeprazole) cut ulcer risk by 80% when co-prescribed.[3][5]
Differences from Ibuprofen or Acetaminophen
Aspirin edges out ibuprofen in bleeding potential (1.5-2x higher), while acetaminophen rarely causes stomach issues but risks liver damage instead.[1][2]
Sources
[1]: FDA Aspirin Label
[2]: NEJM Review on NSAID Gastropathy
[3]: AGA Guidelines on GI Risks
[4]: Cochrane NSAID Ulcer Review
[5]: Lancet PPI Prevention Study