Diphenhydramine (oral)

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# Overview
Diphenhydramine (oral) is an analgesic and antihistamine that is FDA approved for the treatment of temporarily relieves symptoms of the common cold such as runny nose, sneezing, itchy watery eyes, and itchy nose or throat.   Common adverse reactions include xerostomia, dizziness, dyskinesia, sedation, somnolence, dryness of nasal mucosa, pharyngeal dryness, and thick sputum.

# Adult Indications and Dosage

## FDA-Labeled Indications and Dosage (Adult)
- Temporarily relieves these symptoms due to hay fever or other upper respiratory allergies:
- Runny nose
- Sneezing
- Itchy, watery eyes
- Itchy nose or throat
- Temporarily relieves these symptoms of the common cold:
- Runny nose
- Sneezing
- Dosing Information
- Take every 4 to 6 hours, not more than 6 doses in 24 hours

## Off-Label Use and Dosage (Adult)

### Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Diphenhydramine in adult patients.

### NonGuideline-Supported Use
There is limited information regarding Off-Label Non-Guideline-Supported Use of Diphenhydramine in adult patients.

# Pediatric Indications and Dosage

## FDA-Labeled Indications and Dosage (Pediatric)
There is limited information regarding FDA-Labeled Use of Diphenhydramine (oral) in pediatric patients.

## Off-Label Use and Dosage (Pediatric)

### Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Diphenhydramine in pediatric patients.

### NonGuideline-Supported Use
There is limited information regarding Off-Label NonGuideline-Supported Use of Diphenhydramine in pediatric patients.

# Contraindications
- Diphenhydramine is contraindicated in persons with known hypersensitivity.

# Warnings
- Do not use with any other product containing diphenhydramine, even one used on skin
- To make a child sleepy
- Ask a doctor before use if you have glaucoma
- Trouble urinating due to an enlarged prostate gland
- A breathing problem such as emphysema or chronic bronchitis
- Ask a doctor or pharmacist before use if you are taking sedatives or tranquilizers
When using this product
marked drowsiness may occur
avoid alcoholic drinks
excitability may occur, especially in children
alcohol, sedatives and tranquilizers may increase drowsiness
be careful when driving a motor vehicle or operating machinery
If pregnant or breast-feeding,
ask a health professional before use.
Keep out of reach of children.
In case of overdose, get medical help or contact a Poison Control Center right away.

# Adverse Reactions

## Clinical Trials Experience

### Digestive
- Xerostomia
- Sedation
- Dizziness
- Dyskinesia
- Somnolence
- Dryness of nasal mucosa
- Pharyngeal dryness
- Thick sputum
- Bronchial dryness
- Anaphylaxis reaction

## Postmarketing Experience
There is limited information regarding Postmarketing Experience of Diphenhydramine in the drug label.

# Drug Interactions
There is limited information regarding drug interactions of Diphenhydramine in the drug label.

# Use in Specific Populations

### Pregnancy
Pregnancy Category (FDA): B
- Pregnancy Category
Pregnancy Category (AUS):
- Australian Drug Evaluation Committee (ADEC) Pregnancy Category
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Diphenhydramine in women who are pregnant.

### Labor and Delivery
There is no FDA guidance on use of Diphenhydramine during labor and delivery.

### Nursing Mothers
There is no FDA guidance on the use of Diphenhydramine with respect to nursing mothers.

### Pediatric Use
- Keep out of reach of children.
- In case of overdose, get medical help or contact a Poison Control Center right away.

### Geriatic Use
There is no FDA guidance on the use of Diphenhydramine with respect to geriatric patients.

### Gender
There is no FDA guidance on the use of Diphenhydramine with respect to specific gender populations.

### Race
There is no FDA guidance on the use of Diphenhydramine with respect to specific racial populations.

### Renal Impairment
There is no FDA guidance on the use of Diphenhydramine in patients with renal impairment.

### Hepatic Impairment
There is no FDA guidance on the use of Diphenhydramine in patients with hepatic impairment.

### Females of Reproductive Potential and Males
There is no FDA guidance on the use of Diphenhydramine in women of reproductive potentials and males.

### Immunocompromised Patients
There is no FDA guidance one the use of Diphenhydramine in patients who are immunocompromised.

# Administration and Monitoring

### Administration
- Intramuscular
- Intravenous
- Oral

### Monitoring
There is limited information regarding Monitoring of Diphenhydramine in the drug label.

# IV Compatibility
There is limited information regarding IV Compatibility of Diphenhydramine in the drug label.

# Overdosage
There is limited information regarding Chronic Overdose of Diphenhydramine in the drug label.

# Pharmacology

## Mechanism of Action
- Diphenhydramine is an inverse agonist of the histamine H1 receptor. It is a member of the ethanolamine class of antihistaminergic agents. By reversing the effects of histamine on the capillaries, it can reduce the intensity of allergic symptoms. It also crosses the bloodbrain barrier and antagonizes the H1 receptors centrally. Its effects on central H1 receptors cause drowsiness.
- Like many other first-generation antihistamines, diphenhydramine is also a potent antimuscarinic (a competitive antagonist of muscarinic acetylcholine receptors) and, as such, at high doses can cause anticholinergic syndrome.

## Structure

## Pharmacodynamics
There is limited information regarding Pharmacodynamics of Diphenhydramine (oral) in the drug label.

## Pharmacokinetics
There is limited information regarding Pharmacokinetics of Diphenhydramine (oral) in the drug label.

## Nonclinical Toxicology
There is limited information regarding Nonclinical Toxicology of Diphenhydramine in the drug label.

# Clinical Studies
There is limited information regarding Clinical Studies of Diphenhydramine in the drug label.

# How Supplied
- Each tablet contains: calcium 20 mg

## Storage
- Store at 20-25C

# Images

## Drug Images

## Package and Label Display Panel

# Patient Counseling Information
- Marked drowsiness may occur
- Avoid alcoholic drinks
- Excitability may occur, especially in children
- Alcohol, sedatives and tranquilizers may increase drowsiness
- Be careful when driving a motor vehicle or operating machinery

# Precautions with Alcohol
- Avoid alcoholic drinks.
- Alcohol, sedatives and tranquilizers may increase drowsiness.

# Brand Names
- Benadryl
- Benylin Decongestant Cough
- Diphenhist
- Diphenyl
- Genahist
- Geridryl
- Nytol Quickcaps
- Nytol Quickgels

# Look-Alike Drug Names
- Benadryl  - benazepril
- diphenhydrAMINE  - dimenhyDRINATE

# Drug Shortage Status

# Price