Why Old Aspirin Smells Like Vinegar

Aspirin is a chemical compound synthesized from acetylsalicylic acid, extracted from the bark of the willow tree; the bark was initially used by the ancient Greeks and Native Americans to cure fever and pain. Salicylic acid tastes bitter and irritates the stomach. A German chemist, Hoffman synthesized the acetyl derivative of salicylic acid in 1893 in response to the insistence of his father, who took salicylic acid to cure rheumatism.

Today Aspirin is the first rate drug for mild to moderate pain, fever, and inflammation due to arthritis or injury. As an analgesic drug, it is more effective than codeine. It is to be cautioned that prolonged use of Aspirin may cause a slight gastrointestinal bleeding that can over time cause iron deficiency and gastric ulcers.

Aspirin Why Old Aspirin Smells Like Vinegar

To avoid complications use of enteric-coated aspirin is advisable, which does not let it dissolve before reaching the intestine. Aspirin should not be given to children suffering from chicken pox or influenza, because it increases the risk of contracting the fatal Reye’s syndrome, a disease that affects brain and abdominal organs.

Use of aspirin is believed to react side by side with synthesis of prostaglandins, which results in inflammation and fever. Anti-clotting activities of aspirin have shown that half an aspirin tablet a day may reduce the risk of cardiac arrest and stroke in some cases.

Like any other drug, aspirin also has an expiry date. Upon expiry, it turns out to be ineffective and detrimental / toxic for the body. It is known to have characteristic vinegary smell when it gets expired. After expiry, its taste very much resembles to that of vinegar. So the answer to the WHY of the title is explained by aspirin’s chemical composition.

As far as chemical composition of Aspirin is concerned, it is chiefly made up of salicylic and acetic acid. These two compounds are mixed together with hydrogen catalysts to synthesize the drug we use. When an aspirin gets old, it tends to react with the moisture absorbed from the air.

When hydrogen atoms are lost, the aspirin loses its vigor, and assumes a reversible reaction tending to reproduce its original salicylic acid and acetic acid components. The acetic acid found in aspirin is also a major component of vinegar. The foregoing amply explains why aspirin smells like vinegar when expired.

The negative reaction that results from moisture makes it compulsory for the manufacturer to seal the bottles while the user is supposed to keep it in a cool and dry place. To fully ensure a moist free environment, a small sachet of silicone gel is placed inside the bottle to absorb any moisture if left inside before the bottles are sealed intact. Some modern dayaspirin tablets, now a day, are coated with a chemical that wards off moisture from the contents of the tablet. Resultantly, they last long.

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