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Benadryl® AH

Uses|Precautions & Warnings|Side Effects|Interactions|Dosage


What is Benadryl® AH used for?

Benadryl® AH (diphenhydramine) is a type of drug known as an antihistamine. Benadryl® AH works by binding to histamine H-1 receptors on various cells throughout the body, including white blood cells. By blocking histamine, it prevents symptoms such as sneezing, itchiness, redness, inflammation, and runny nose.

Benadryl® AH is used to treat the following:

  • Seasonal allergic rhinitis
  • Hay fever
  • Vasomotor rhinitis
  • Allergic conjunctivitis
  • Relieve symptoms of allergic reaction
  • Dermatographism
  • Adjunct to epinephrine for anaphylactic reactions
  • Motion sickness
  • Symptoms of parkinsonism

How should I take Benadryl® AH?

Benadryl® AH is available as an oral capsule and syrup. The oral tablet and syrup should be taken by mouth. The capsules should be swallowed whole without chewing or crushing them.

The syrup should be measured using the included medical-grade measuring cup or dropper. Do not use a regular household spoon, as this may not measure the correct dose.

How do I store Benadryl® AH?

This drug should be stored at room temperature (<30°C) and be protected from light and moisture. Do not freeze this product. For safety, keep out of the reach of children and pets.

Always check the label before using this product. Do not use if the printed expiration date has passed, the product seal has been broken, or the product has changed in color, odor, or consistency.

Do not dispose of this product by pouring it down the drain, toilet, or into the environment. Ask your pharmacist regarding the proper way and location of disposal.

Precautions & Warnings

What should I know before using Benadryl® AH?

Before using this medication, inform your doctor if:

  • You have ever had an allergic reaction to Benadryl® AH (diphenhydramine) or other antihistamines.
  • You have a history of allergy to other medications, food, or other substances.
  • You are taking other medications.
  • You have underlying health conditions.

Is it safe during pregnancy or breastfeeding?

Benadryl® AH is a pregnancy category B drug. There are no adequate and well-controlled studies using Benadryl® AH in pregnant women. This drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, as determined by your doctor.

This drug is excreted in breast milk. This drug should not be used while breastfeeding unless directed by your doctor.

Side Effects

What side effects can occur when using Benadryl® AH?

All drugs have the potential to elicit side effects even with normal use. Many side effects are dose-related and will resolve when it is adjusted or at the end of therapy.

Potential side effects while using this drug include:

  • Drowsiness
  • Dizziness
  • Insomnia
  • Agitation, irritability
  • Nervousness
  • Eye irritation
  • Blurred vision
  • Dry mouth or eyes
  • Photosensitivity
  • Hypotension
  • Palpitation
  • Urinary frequency

Severe adverse reactions:

  • Skin rash
  • Redness
  • Blistering of the lips, eyes, or mouth
  • Fever
  • Chills
  • Headache
  • Jaundice
  • Seizure

You may experience some, none, or other side effects not mentioned above. If you experience serious adverse reactions, you must stop taking the drug immediately. If you have any concerns about a side effect or it becomes bothersome, consult your doctor or pharmacist.


What drugs may interact with Benadryl® AH?

This drug may interact with other medications. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist.

Known drugs and their interactions with medication include:

  • Sedatives
    • Increased symptoms of drowsiness
  • Hypnotics
    • Increased symptoms of drowsiness
  • Other antihistamines
    • Increased symptoms of drowsiness
  • MAOIs
    • Prolonged and enhanced anticholinergic effects

If you experience an adverse drug interaction, stop taking this drug and continue taking your other medication. Inform your doctor immediately to reevaluate your treatment plan. Your dose may need to be adjusted, substituted with another drug, or discontinue using the drug.

Does food or alcohol interact with Benadryl® AH?

There are no known food interactions with Benadryl® AH, however, it is best to take this medication with meals. Do not take Benadryl® AH with alcohol as it may potentiate the effects of drowsiness and CNS depression.

Inform your doctor or pharmacist if you have any concerns regarding food-drug interactions.

What health conditions may interact with Benadryl® AH?

This drug should be taken with caution if you have any of the following conditions or risk factors:

  • Bronchial asthma
  • Narrow-angle glaucoma
  • Increased intraocular pressure
  • Peptic ulcer
  • Pyloroduodenal obstruction
  • Hyperthyroidism
  • Cardiovascular disease
  • Hypertension
  • Elderly patients over 60 years old

Inform your doctor or pharmacist if you have any concerns regarding specific health conditions.


The information provided is not a substitute for any medical advice. You should ALWAYS consult your doctor or pharmacist before using Benadryl® AH.

What is the dose of Benadryl® AH for an adult?

For treating allergic conditions

  • Take 50 mg 3 to 4 times per day

For treating motion sickness

  • Take 25 to 50 mg 30 minutes before traveling or exposure to motion.

What is the dose of Benadryl® AH for a child?

For treating allergic conditions and motion sickness

  • Body weight >20 lbs. (9 kg): Give 12.5 to 25 mg (1 to 2 teaspoons) 3 to 4 times per day.
  • Recommended dose: 5mg/kg every 24 hours.
  • Maximum daily dose: 300 mg
  • Ages <2 years: Not recommended for use. Consult a pediatrician for alternative treatment.

How is Benadryl® AH available?

This drug is available in the following dosage forms and strengths:

  • Benadryl® AH capsules 25 mg, 50 mg
  • Benadryl® AH syrup 12.5 mg/5 mL

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of this drug, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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Written by Stephanie Nicole Nera, RPh, PharmD Updated Dec 03, 2020