Diphenhydramine, widely recognized as the active ingredient in medications like Benadryl, is a common antihistamine. It is frequently used to alleviate symptoms associated with allergies, such as sneezing, runny nose, and itchy, watery eyes. Beyond allergy relief, diphenhydramine also serves as a sleep aid due to its sedative properties. Many people encounter expired medications in their homes and wonder whether these products retain their effectiveness and safety.
Why Medications Expire
Medication expiration dates are determined by pharmaceutical manufacturers through stability testing. These tests assess how a drug’s chemical and physical properties change over time under specific environmental conditions, including temperature, humidity, and light. The expiration date printed on a product guarantees its full potency, quality, and purity when stored correctly.
The U.S. Food and Drug Administration (FDA) requires manufacturers to provide data from these stability studies before a drug receives approval, ensuring the product maintains its strength and integrity. Drug products are typically assigned an expiration date ranging from 12 to 60 months from their manufacturing date. Over time, the active ingredients in medications can degrade, reducing their intended effects.
Potential Risks of Expired Diphenhydramine
A primary risk of taking expired diphenhydramine is a reduction in its effectiveness. As the active ingredient degrades over time, the medication may become less potent, meaning it might not provide adequate relief for allergy symptoms or help with sleep. While some studies suggest many medications can retain a significant portion of their potency for years beyond their expiration date, this is not universally guaranteed. Relying on expired diphenhydramine might result in inadequate treatment.
Another concern is the potential for medications to degrade into harmful byproducts. While diphenhydramine is generally considered safe past expiration, degradation can lead to unpredictable effects. For instance, certain medications like tetracyclines have been known to break down into toxic compounds. Any visual changes in the medication, such as discoloration, cloudiness, or a change in texture, should prompt immediate disposal, as these can indicate chemical degradation.
Proper Storage and Disposal
Proper storage is important for maintaining diphenhydramine’s stability and effectiveness until its expiration date. Oral forms should be stored at room temperature, ideally between 68°F and 77°F (20°C and 25°C). Keep the medication in a cool, dry place, away from direct sunlight, heat, and humidity, as these conditions can accelerate degradation. Always ensure medications are stored out of the reach of children and pets.
When diphenhydramine or any medication is expired or no longer needed, safe disposal is recommended. The most appropriate method is to utilize drug take-back programs, found at local pharmacies, police stations, or through mail-back programs. If a take-back option is not readily available, most medications can be disposed of in household trash.
To do this, remove the medication from its original container, mix it with an undesirable substance like dirt, cat litter, or used coffee grounds, then place the mixture in a sealed bag before putting it in the trash. Avoid flushing medications down the toilet or drain unless specifically instructed by the FDA, which is not the case for diphenhydramine. Remember to scratch out all personal information on the prescription label before discarding the packaging to protect your privacy.