May be time to throw out that old Aspirin
If your old bottle of aspirin is starting to smell like vinegar it may be time to throw it away! Check the expiration date. Acetic acid is the main taste and odor component of Vinegar and when Aspirin expires/ages it reacts with the moisture in the air and decomposes to salicylic acid and acetic acid. It is the Acetic acid that you are smelling , the same component that Vinegar is made up of. Aspirin makers put a special coating on aspirin to help protect it from moisture and also from the acid in your stomach. This coating does prolong the life of the aspirin but it will eventually expire. It's better to be safe than sorry and if that old aspirin bottle is starting to smell like vinegar you might want to just chuck it right in the garbage.