1 What is Benadryl?

Brand: Benadryl, Genahist, Sominex, Unisom, Q- Dryl, Aler- Tab, Dytuss, Quenalin, Siladryl, Siphen Cough, Simply Sleep, Sleep- ettes, Valu- Dryl

Generic: Diphenhydramine

Benadryl is a drug which is used to treat allergic reactions or anaphylaxis. This drug is also used to treat motion sickness and parkinsonism.

Benadryl is available as an injection solution containing diphenhydramine hydrochloride 50 milligram in 1 milliliter. It is also available as a 50 mg capsule, oral solution/ syrup and in the topical form.


You should read the product information leaflet before using this medication. If you have any questions, ask your doctor or pharmacist.

Benadryl capsule should be taken by mouth as instructed by your doctor. Do not crush or chew the drug because it may diminish its effects. This medication should be taken with a full glass of water unless your doctor tells you otherwise. You should swallow the drug whole.For Benadryl syrup, a measuring spoon should be used and not an ordinary household spoon.

Benadryl injection should be given by a health care professional.

Benadryl topical is to be applied to the skin only. Avoid using it in the face, groin, or underarms, or for diaper rash, unless told so by your doctor. First, wash and dry your hand before applying. The affected area should be cleansed and dried. The medication should be applied as a thin film to be gently rubbed in, as instructed by your doctor. Avoid covering or wrapping the treated are. Wash your hands after use. Avoid contact with eyes, mouth or mucous membranes. If contact occurs, rinse with plenty of water.

Your dosage is based on your medical condition and the way you will respond to treatment. Take this drug regularly to experience the most benefits. You should also take this drug at the same time each day.

If you miss a dose, use it as soon as you remember. Continue to use it as prescribed by your doctor or as stated on the package label.


Benadryl may interact with medications such as:

  • Antihistamines applied to the skin (such as diphenhydramine cream, ointment, spray)
  • Antispasmodics (e.g., atropine, belladonna alkaloids)
  • Drugs for Parkinson's disease (e.g., anticholinergics such as benztropine, trihexyphenidyl)
  • MAO inhibitors (isocarboxazid, linezolid, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, selegiline, tranylcypromine)
  • Scopolamine
  • Tricyclic antidepressants (e.g., amitriptyline)
  • Certain antihistamines (e.g., dimenhydrinate)
  • Anti-seizure drugs (e.g., carbamazepine)
  • Medicine for sleep or anxiety (e.g., alprazolam, diazepam, zolpidem)
  • Muscle relaxants
  • Narcotic pain relievers (e.g., codeine)
  • Psychiatric medicines (e.g., chlorpromazine, risperidone, amitriptyline, trazodone)

Side Effects

There are no side effects known aside from a possible allergic reaction in people who have previous or unknown hypersensitivity to the drug.

Watch out for signs of allergic reactions such as:

  • Rash
  • Itching
  • Swelling


Before taking this medication, tell your doctor or pharmacist if you have the following:

  • Allergy to diphenhydramine
  • Breathing problems (e.g., asthma, emphysema)
  • Glaucoma
  • Heart problems
  • High blood pressure
  • Liver disease
  • Mental/mood changes
  • Seizures
  • Stomach problems (e.g., ulcers, obstruction)
  • An overactive thyroid gland
  • Difficulty urinating (e.g., due to an enlarged prostate gland)
  • Pregnancy or lactation
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