Diphenhydramine

Overview

It's in many nighttime cold and pain products (look for 'PM'). Newer antihistamines like cetirizine or loratadine cause less drowsiness.

What it's used for

• Allergy symptoms and hives
• Occasional trouble sleeping
• Motion sickness

How to take it

• Follow the label. Don't take more than the label allows in 24 hours.
• Don't use it to make a child sleepy. Don't give it to children under 2 unless a provider says to.
• Check other products for diphenhydramine so you don't double up.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

• Sleepiness
• Dry mouth
• Dizziness
• Constipation
• Next-day grogginess

Warnings

• Older adults: it raises the risk of confusion and falls; ask about alternatives.
• Ask a provider first if you have glaucoma, an enlarged prostate, or breathing problems.
• Doesn't replace epinephrine for a severe allergic reaction.

Other medicines, foods, and alcohol

• Alcohol and sedating medicines add to drowsiness.
• Don't use with other antihistamines, including skin creams with diphenhydramine.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Ask your provider before using it in pregnancy or while breastfeeding.

Missed doses, overdose, and storage

If you miss a dose

This medicine is often taken only when needed. If you take it on a schedule, take a missed dose when you remember, unless it's almost time for the next one. Don't double up.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

• Seasonal allergies (hay fever)
• Hives
• Insomnia
• Motion sickness