Benadryl (Diphenhydramine) is a brand name over the counter medication that’s classified as an antihistamine. Diphenhydramine is an antihistamine mainly used to treat allergies. In United State and Canada it is the first generation antihistamine diphenhydramine.

It is available for oral and topical use. It is marketed without a prescription by Johnson & Johnson. Before 2007, Benadryl was marketed by Pfizer Consumer Healthcare. 

Diphenhydramine can also cause sleepiness. It is not recommended for children under the age of six where it has caused fatalities. In 2014, the FDA posted a warning about swallowing Benadryl gel products that were meant to be used topically. 

Ingredients:- 

Non-medicinal ingredients: celluloses, dicalcium phosphate, D&C Red No.27, Polylobate, starch, stearic acid, titanium dioxide, wax and zinc stearate. Each pink, film coated caplet imprinted Benadryl on both sides contains 25 mg of diphenhydramine. This medication is available as a 25 mg capsule.

How to Take Benadryl

Benadryl can be taken with or without food. For High fever or other respiratory allergies, Benadryl is typically taken every 4 to 6 hours. If you have trouble swallowing who tablets, Benadryl tablets can be crushed. If Benadryl is used to treat itchy skin, it should be applied up 3 to 4 times daily.

Dosage 

Benadryl dosage is based on your age, medical condition and response to treatment.

For High Fever, Allergies, Symptoms of Cold and others:-

Benadryl liquid for children 12.5 mg per teaspoon
Children of 12 years and older age take 25 to 50 mg, every 4 t0 6 hours.
Children of 6 years to 11 years age take 12.5 to 25 mg, every 4 to 6 hours.
Children under 6 years use only according to the doctor’s instructions.
Adults take Benadryl dosage 25 to 50 mg, every 4 to 6 hours.
For pain, itchy skin and insect bites use Benadryl cream, Gel or spray 3 to 4 times daily.

Benadryl Generic

Genahist, Sominex, Unisom are the brand name of generic brand Benadryl. It is also used to relieve the symptoms of allergy, high fever and the common cold. The generic antihistamine hydroxyzine is used for the short term treatment of anxiety.

Uses

Benadryl is used to relieve symptoms of allergy and high fever.
It is used to prevent and treat nausea, vomiting and dizziness caused by motion sickness.
It can be used to help you relax and fall asleep
It is used to treat sneezing, runny nose, watery eyes, hives, harsh skin and itching.
It is also used to treat the symptoms of Parkinson’s disease.

Contraindication

The following conditions are contraindicated with Benadryl

Overactive thyroid gland
High Blood Pressure
Increased pressure in the eye
Closed angle glaucoma
Cannot empty bladder
Chronic idiopathic constipation
Enlarged prostate
Blockage of urinary bladder
Stenosing peptic ulcer

Benadryl Interactions

The following drugs interact with Benadryl and may cause problems.

Other medications that contain diphenhydramine, including creams and gels
Alcohol
Allergy medications
Diazepam (Valium)
Monoamine oxidase inhibitors
Anxiety medications
Sedatives

Examples of Benadryl

Examples of different Benadryl products and their ingredients include:

Benadryl Allergy

This product contains one active ingredient:  diphenhydramine, which is an antihistamine.

Benadryl Allergy plus Congestion

This product contains two active ingredients: diphenhydramine, an antihistamine and phenylephrine, a decongestant.

Benadryl Itch Cooling Gel

This product doesn’t contain the usual antihistamine. It only contains camphor, which is a type of pain reliever that’s applied to the skin.

Benadryl Itch Stopping Cream

This product contains two active ingredients: diphenhydramine, an antihistamine and Zinc, a skin protectant.

Side Effects:-

Followings are the side effects of Benadryl

Dry Mouth
Constipation
Dizziness
Drowsiness
Nausea
Excitation 
Thickening of Mucus
Restlessness
Nervousness
Ringing in the Ears
Blurred Vision
Fast Heartbeat
Impaired Thinking
Seizures
Sleepiness
Headache
Weakness