Aspirin (acetylsalicylic acid) is an ester of acetic acid and salicylic acid (ortho-hydroxybenzoic acid). Deterioration of aspirin results in a chemical breakdown with release of salicylic acid and acetic acid.


Deterioration of aspirin can occur when formulations are exposed to water.


Risk for deterioration:

(1) old preparation that has been previously opened

(2) exposure to moisture (getting the pills wet)

(3) exposure to humidity (failure to close container lid securely)

(4) lack of an outer coating on the pills


Signs of deterioration:

(1) discoloration of pills

(2) crumbling of pills

(3) smell of vinegar (from the release of acetic acid)


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