Diphenhydramine: uses, dosing, side effects & brands

The label's Pregnancy section reports that animal reproduction studies in rats and rabbits (at doses up to 5 times the human dose) revealed no evidence of impaired fertility or harm to the fetus, but there are no adequate and well-controlled studies in pregnant women. Because animal studies are not always predictive of human response, the label states the drug should be used during pregnancy only if clearly needed. Discuss use in pregnancy with your prescriber. This is what diphenhydramine's FDA label says; whether to use it in pregnancy is your prescriber's decision.

It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run diphenhydramine against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.

We track 4 diphenhydramine-containing products in the U.S.: Benadryl, Benadryl Preservative Free, Benylin and Diphenhydramine Hydrochloride. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.

Across the brands we track, diphenhydramine is currently marketed as tablet, kit, injectable, syrup, solution and capsule, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Yes. Our catalog lists 1 generic diphenhydramine product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.

The FDA's Enforcement database lists 3 recall records whose product description mentions diphenhydramine. The most recent: Diphenhydramine HCl 50 mg (Dec 12, 2024). A recall applies to specific lots, not to the drug as a whole — check the record for the affected lot numbers.

Other medicines: we hold source-cited interaction answers for Can you take Benadryl with Claritin?, Can you take Benadryl with Zyrtec?, Can you take Benadryl with ibuprofen? and Can you take Benadryl with Tylenol? and more. This is what the FDA label and our cited sources say — it is not a complete list. Your pharmacist can check your own combination.

Drowsiness is the most common effect, which is why it is also sold as a sleep aid. Its anticholinergic action commonly causes dry mouth, dry eyes, blurred vision, constipation, and thickened nasal mucus. Dizziness and next-day grogginess are also frequent. In children it can occasionally cause the opposite of sedation, restlessness and excitability.

Its anticholinergic effects hit older adults harder, causing confusion, memory problems, blurred vision, urinary retention, constipation, dizziness, and a higher risk of falls. It appears on the Beers list of medications best avoided in older people, and regular long-term anticholinergic use has been associated with greater dementia risk. Safer alternatives usually exist for allergies or sleep in this age group.

Call for trouble urinating or inability to urinate, new or worsening confusion, a fast or pounding heartbeat, or severe dizziness. It can worsen glaucoma, an enlarged prostate, and some breathing conditions, so those need caution. Very high doses can cause agitation, hallucinations, seizures, and dangerous heart rhythms, which are a medical emergency.

Drowsiness, dry mouth, and mild constipation are expected and fade as the dose wears off. Stop and get help for inability to urinate, confusion or hallucinations, a racing heartbeat, or seizures. It is not meant for nightly long-term sleep use; if you need it regularly, that is a reason to see your doctor rather than keep taking it.