Does Cough Syrup Expire?

A nasty cough is not only miserable but also tends to overstay its welcome. When we come down with a cold virus, post-nasal drip causes inflammation in our upper respiratory airways, which can leave a cough hanging around for as long as two weeks (via The Guardian). By coughing, our body protects us from irritants entering the throat. While it is an essential bodily function, coughing can be both strenuous and painful when we're sick.

Liquid cough syrup works by providing temporary relief from mild cold or allergy symptoms such as sneezing, runny nose, and cough (per WebMD). Through the use of cough suppressant ingredients such as dextromethorphan, the chemical signals to the brain to stop coughing and blocks the reflex. Additionally, some cough syrups also contain expectorants to help break up mucus, decongestants to help open the airways, and antihistamines to relieve inflammation, according to CNN.

Cough syrup is a staple in many household medicine cabinets and is ready to use come wintertime, but it doesn't stay potent forever. Just how long can you keep cough syrup around?

How to properly store cough syrup

Emergency-medicine specialist Dr. Jack Springer discusses the meaning of the expiration date on the labels of over-the-counter (OTC) medications, telling Insider, "The vast majority of medications maintain most of their potency years after the posted expiration date. That date is the date after which full potency cannot be guaranteed by the manufacturer." Dr. Springer goes on to say, "The expiration date doesn't really indicate a point at which the medication is no longer effective or has become unsafe to use."

However, liquid medications do not follow these same guidelines — including cough syrup. Because liquid medications undergo chemical changes when stored for extended periods of time, they don't withstand the test of time in the same way dry medications do (via Insider). Cough syrup breaks down much faster and should therefore be discarded by the expiration date.

When it comes to proper storage of cough syrup, clinical adviser at digital-health startup Medzino Dr. Kim Langdon explains via Insider, "Store cough syrup in the refrigerator if you want to prolong the effectiveness and taste. The risk of contamination is based on the number of openings and time." To further safeguard against contamination, be sure to pour out the proper dosage rather than drinking from the bottle itself.