Which of the following is a known side effect of aspirin?

• A. Tinnitus
• B. GI upset
• C. Bronchospasm
• D. GI bleeding

Answer: (D)

Aspirin’s known adverse effects are driven by its action as a COX inhibitor, which reduces prostaglandin synthesis. Prostaglandins help protect the gastric mucosa and support normal platelet function. When aspirin irreversibly inhibits COX-1 in platelets, these effects last for the platelet’s lifespan, increasing bleeding risk. At the same time, decreased protective prostaglandins leave the gastric lining more susceptible to irritation and ulceration, which can manifest as GI bleeding, especially with longer use or higher doses.

Other options relate to less consistent or context-dependent reactions: tinnitus can occur with high salicylate levels, and bronchospasm can happen in aspirin-sensitive individuals, but GI bleeding is a more definite and clinically significant known side effect of standard aspirin use. GI upset is common but does not carry the same level of risk for serious bleeding as GI bleeding does.