diphenhydramine
Diphenhydramine (Benadryl) is an over-the-counter (OTC) oral medication that's commonly used to treat allergies, common cold symptoms, and itching. Because it makes most people very sleepy, it can also be used as an occasional sleep aid.
What is Diphenhydramine (Benadryl)?
What is Diphenhydramine (Benadryl) used for?
Allergies
Common cold symptoms
Trouble sleeping for people 12 years and older
How Diphenhydramine (Benadryl) works
Diphenhydramine (Benadryl) is an antihistamine. It blocks the action of histamine, a natural chemical in your body that causes sneezing, itching, and runny nose.
By stopping histamine from working, diphenhydramine (Benadryl) can help relieve symptoms from allergies or the common cold. And since it tends to cause a lot of drowsiness while it's working, it can also be used to help with trouble sleeping.
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What are the side effects of Diphenhydramine (Benadryl)?
Common Side Effects
- Sleepiness
- Dizziness
- Dry mouth, nose, and throat
- Headache
- Constipation
- Blurry vision
Other Side Effects
- Nausea
- Vomiting
- Loss of appetite
- Muscle weakness
- Nervousness
- Hyperactivity (more common in children)
- Trouble urinating
Source: DailyMed
The following side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
- Sudden eye pain or change in vision such as blurry vision, seeing halos around lights, vision loss
- Trouble passing urine
Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):
- Constipation
- Drowsiness
- Dry mouth
- Headache
- Upset stomach
Pros and cons of Diphenhydramine (Benadryl)
Pros
Can help relieve allergy and cold symptoms within about 30 minutes
Can be used in children as young as 6 years old with allergy and cold symptoms
Can help with occasional sleep problems (12 years and older)
Available as a lower-cost generic
Available OTC in several different dosage forms
Cons
Not the best option for long-term use
Can cause drowsiness the next day when used for sleep
Can cause hyperactivity in some children
Might not be safe for people with breathing problems, glaucoma, or problems with urinating
Can impair your ability to drive or do tasks that require alertness
Pharmacist tips for Diphenhydramine (Benadryl)
It's common to feel tired after taking diphenhydramine (Benadryl). Don't drive or do anything that requires you to be alert until you know how diphenhydramine (Benadryl) affects you. Drinking alcohol raises the risk of this side effect, so it's best to avoid drinking alcohol while taking this medication.
Diphenhydramine (Benadryl) can be unsafe for older adults. It raises the risk of falling because it can make you feel dizzy, tired, or cause a drop in your blood pressure. Be sure to discuss taking diphenhydramine (Benadryl) with your provider before you start it if you're an older adult, as this might not be the best option for you.
If you or your child is taking the liquid form of diphenhydramine (Benadryl), use a dosing syringe or medication cup to measure the dose in milliliters. Never use household spoons to measure medications because they won't be as accurate. Talk to your pharmacist or provider if you don't have a proper dosing device.
If you're using the dissolvable tablet form of diphenhydramine (Benadryl), place the tablet on your tongue and let it fully dissolve. Do not chew or swallow it because it will affect how well it works.
Don't use multiple diphenhydramine (Benadryl) products at the same time, including creams you use on the skin. This can raise your risk of experiencing side effects from this medication.
Frequently asked questions about Diphenhydramine (Benadryl)
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What are the risks and warnings for Diphenhydramine (Benadryl)?
Diphenhydramine (Benadryl) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Accidental overdose
Risk factors: Taking other products with diphenhydramine
Many OTC products contain diphenhydramine, the main ingredient in diphenhydramine (Benadryl). It's not safe to use more than one medication containing diphenhydramine at the same time, including products used on the skin. If you take too much diphenhydramine (Benadryl) you might experience dry eyes or mouth, fast heart rate, trouble urinating, fever, and constipation. Overdosing on diphenhydramine (Benadryl) can also lead to more serious side effects like severe confusion, seizures, low blood pressure, involuntary muscle spasms, hallucinations (seeing things that aren't there), and heart rhythm problems.
In fact, the FDA released a warning to avoid high doses of diphenhydramine. To prevent accidentally overdosing with diphenhydramine (Benadryl), read package labels carefully to make sure you take the right dose. If you're not sure if a product contains diphenhydramine, ask your provider or pharmacist.
Excessive sleepiness
Risk factors: Taking diphenhydramine (Benadryl) while drinking alcohol | Taking other medications that cause drowsiness | Older adults
Diphenhydramine (Benadryl) causes severe drowsiness for many people who take it. This can affect your ability to focus, think, and react. This side effect can be especially dangerous for older adults (ages 65 years and older), because it raises the risk of falls. It's also more likely to cause drowsiness the next day in older adults. Sleepiness from diphenhydramine (Benadryl) can be made more intense if you drink alcohol while taking this medication, or take other medications that cause drowsiness (e.g., opioids, benzodiazepines, sleep medications). Avoid activities that require you to be alert, such as driving a car or operating machinery, until you know how this medication affects you.
Worsening of certain health problems
Risk factors: Glaucoma | Enlarged prostate | Breathing problems | Kidney problems
Talk to your provider before using diphenhydramine (Benadryl) if you have glaucoma, an enlarged prostate, problems with breathing (e.g., emphysema), or kidney problems. Taking diphenhydramine (Benadryl) can make these problems worse and could lead to serious side effects.
Diphenhydramine (Benadryl) dosage forms
Typical dosing for Diphenhydramine (Benadryl)
Diphenhydramine (Benadryl) comes in many different dosage forms (e.g., tablets, capsules, liquid). Be sure to check the package label to make sure you're taking the correct dose. Ask your provider or pharmacist if you have questions about dosing.
Allergies and common cold symptoms:
Adults and children 12 years and older: The typical dose is 25 mg to 50 mg by mouth every 4 to 6 hours as needed. Don't take more than 6 doses in a 24-hour period.
Children 6 to 11 years old: The typical dose is 12.5 mg to 25 mg by mouth every 4 to 6 hours as needed. Don't take more than 6 doses in a 24-hour period.
Children under 6 years old: Ask your child's provider.
Children under 2 years old: Don't use.
Trouble sleeping:
Adults and children 12 years and older: The typical dose is 50 mg by mouth at bedtime as needed. Don't take more than one dose in a 24-hour period.
Children under 12 years old: Don't use.
How much does Diphenhydramine (Benadryl) cost?
What are alternatives to Diphenhydramine (Benadryl)?
Allergies
Common cold symptoms
Trouble sleeping for people 12 years and older
Short-term relief of allergy symptoms (runny nose, itchy nose, itchy or watery eyes)
Trouble falling asleep (insomnia)
What is the latest news about Diphenhydramine (Benadryl)?
Diphenhydramine (Benadryl) images
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References
Best studies we foundAbraham, O., et al. (2017). Over-the-counter medications containing diphenhydramine and doxylamine used by older adults to improve sleep. International Journal of Clinical Pharmacy.
American Family Physician. (n.d.). Don’t routinely continue sedative hypnotics (Restoril, Ambien), diphenhydramine (Benadryl), benzodiazepines, or serotonin modulators (trazadone) for long-term treatment of insomnia in geriatric populations. Consider the use of cognitive behavioral therapy as an alternative.
Centers for Disease Control and Prevention. (2020). Spoons are for soup, milliliters are for medicine.
Chattem, Inc. (2023). Unisom sleepminis nighttime sleep-aid- diphenhydramine hcl capsule [package insert]. DailyMed.
Culpepper L, et al. (2015). Over-the-counter agents for the treatment of occasional disturbed sleep or transient insomnia: A systematic review of efficacy and safety. The Primary Care Companion for CNS Disorders.
Huynh, D. A., et al. (2023). Diphenhydramine toxicity. StatPearls.
Johnson & Johnson Consumer Inc. (2023). Childrens benadryl allergy- diphenhydramine hydrochloride solution [package insert]. DailyMed.
Jones Healthcare Group - Packaging Services, Inc. (2023). Benadryl allergy ultratab- diphenhydramine hydrochloride tablet, film coated [package insert]. DailyMed.
Pham, A. Q., et al. (2013). Diphenhydramine and acute kidney injury. Pharmacy and Therapeutics.
Sicari, V., et al. (2023). Diphenhydramine. StatPearls.
U.S. Food and Drug Administration. (2020). FDA warns about serious problems with high doses of the allergy medicine diphenhydramine (Benadryl).
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