How Long Does Benadryl Stay In Your System?

Answer

Thanks for reaching out! first and foremost, Benadryl (diphenhydramine) may certainly be causing some of the side effects you mentioned occurring with your elderly mother. Although Benadryl is relatively short-acting, its effects can be prolonged in the elderly.

Benadryl is an antihistamine that has strong anticholinergic effects, which can cause drowsiness, decreased gut motility, dry mouth, dry eyes, thickening of bronchial secretions, urinary retention, and blurred vision. Benadryl may also cause constipation, diarrhea, or abdominal pain in some patients.

Elderly patients can be especially impacted by the effects of Benadryl. According to the Beers Criteria, Benadryl should be avoided in elderly patients due to the increased risk of confusion, dry mouth, and drowsiness.

How Long Does Benadryl Last?

That brings us to answering specifically how long Benadryl strays in your system.

While the effects of Benadryl generally only last 4 to 6 hours, it takes longer for the drug to be metabolized and eliminated from your system.

In healthy patients, Benadryl has a half-life between 2-8 hours and is cleared completely within 24-48 hours (i.e. one to two days). However, drug clearance in elderly patients can be impacted by the decline in kidney and liver function. Benadryl is extensively metabolized in the liver and dosage reduction may be necessary for patients with liver impairment.

Several studies have shown that some individuals report 'hangover' effects in the morning after Benadryl has been taken at night to help sleep. It isn't overly common, but is more likely to occur in the elderly.

So, it is certainly possible that Benadryl is causing some of the problems you mentioned, however, due to the age of your mother, there certainly could be other things going on. Be sure to talk to your doctor so your mother can be properly evaluated.

What Is Benadryl?

Benadryl is a first-generation antihistamine and is more likely to cause anticholinergic side effects than second-generation antihistamines. Other first-generation antihistamines include Dramamine (dimenhydrinate), Chlor-Trimeton (chlorpheniramine), Tavist (clemastine), and Phenergan (promethazine), among others. These medications cross the blood-brain barrier and have CNS effects like drowsiness and dizziness.

Second-generation antihistamines include Claritin (loratadine), Cetirizine (Zyrtec), and Allegra (fexofenadine) which are much less sedating. Antihistamines are widely used for self-care of allergy symptoms including runny nose, watery eyes, sneezing, and itching of the nose, throat, or eyes. Benadryl may also be used for symptoms of the common cold, allergic reactions, occasional insomnia, and more.

Final Words

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