Diphenhydramine Dosage

The information at Drugs.com is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for Extrapyramidal Reaction

Parenteral: 10 to 50 mg IV or IM as needed. May increase dose to 100 mg if required. Maximum daily dose 400 mg.

Oral: 25 to 50 mg orally every 6 to 8 hours.

Usual Adult Dose for Insomnia

25 to 50 mg orally at bedtime.

Usual Adult Dose for Motion Sickness

Parenteral: 10 to 50 mg IV or IM as needed. May increase dose to 100 mg if required. Maximum daily dose 400 mg.

Oral: 25 to 50 mg orally every 6 to 8 hours. Administer first dose 30 minutes before exposure to motion and repeat before meals and upon retiring for the duration of the journey.

Usual Adult Dose for Cough

25 mg orally every 4 hours as needed, not to exceed 150 mg per day.

Usual Adult Dose for Cold Symptoms

25 to 50 mg orally every 4 to 6 hours as needed, not to exceed 300 mg/24 hours.

Usual Adult Dose for Pruritus

25 to 50 mg orally every 4 to 6 hours as needed, not to exceed 300 mg/24 hours.

Usual Adult Dose for Urticaria

25 to 50 mg orally every 4 to 6 hours as needed, not to exceed 300 mg/24 hours.

Usual Pediatric Dose for Allergic Rhinitis

Greater than or equal to 2 to less than 6 years: 6.25 mg orally every 4 to 6 hours, not to exceed 37.5 mg/24 hours.

Greater than or equal to 6 to less than 12 years: 12.5 to 25 mg orally every 4 to 6 hours, not to exceed 150 mg/24 hours.

Greater than or equal to 12 years: 25 to 50 mg orally every 4 to 6 hours, not to exceed 300 mg/24 hours.

Usual Pediatric Dose for Cold Symptoms

Greater than or equal to 2 to less than 6 years: 6.25 mg orally every 4 to 6 hours, not to exceed 37.5 mg/24 hours.

Greater than or equal to 6 to less than 12 years: 12.5 to 25 mg orally every 4 to 6 hours, not to exceed 150 mg/24 hours.

Greater than or equal to 12 years: 25 to 50 mg orally every 4 to 6 hours, not to exceed 300 mg/24 hours.

Usual Pediatric Dose for Motion Sickness

Greater than or equal to 2 to less than 6 years: 6.25 mg orally every 4 to 6 hours, not to exceed 37.5 mg/24 hours.

Greater than or equal to 6 to less than 12 years: 12.5 to 25 mg orally every 4 to 6 hours, not to exceed 150 mg/24 hours.

Greater than or equal to 12 years: 25 to 50 mg orally every 4 to 6 hours, not to exceed 300 mg/24 hours.

Usual Pediatric Dose for Insomnia

Greater than or equal to 12 years: 25 to 50 mg orally at bedtime.

Usual Pediatric Dose for Cough

Greater than or equal to 2 to less than 6 years: 6.25 mg orally every 4 hours, not to exceed 37.5 mg/24 hours.

Greater than or equal to 6 to less than 12 years: 12.5 mg orally every 4 hours, not to exceed 75 mg/24 hours.

Greater than or equal to 12 years: 25 mg orally every 4 hours, not to exceed 150 mg/24 hours.

Usual Pediatric Dose for Extrapyramidal Reaction

In dystonic reactions: 1 to 2 mg/kg (max: 50 mg) IV or IM [Pediatric Advanced Life Support]

Usual Pediatric Dose for Allergic Reaction

1 to 12 years: 5 mg/kg/day or 150 mg/m2/day administered orally, IM or IV, in equally divided doses every 6 to 8 hours, not to exceed 300 mg/24 hours.

In acute hypersensitivity reactions: 1 to 2 mg/kg IV or IM (max: 50 mg) [Advanced Pediatric Life Support]

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

Diphenhydramine citrate 19 mg is equivalent to 12.5 mg of diphenhydramine hydrochloride.

Precautions

Diphenhydramine should not be used in newborn or premature infants. Because of the higher risk of antihistamines for infants generally, and for newborns and prematures in particular, antihistamine therapy is contraindicated in nursing mothers.

In infants and children, especially, antihistamines in overdosage may cause hallucinations, convulsions, or death.

As in adults, antihistamines may diminish mental alertness in children. In the young child, particularly, they may produce excitation.

Patients should be warned of the sedative effects of diphenhydramine, and advised not to take this drug with alcohol.

Due to the anticholinergic effect of diphenhydramine, it should be used with caution in patients with narrow-angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, prostatic hypertrophy or bladder-neck obstructions. It should also be used with caution in patients with a history of lower respiratory disease, including asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease, or hypertension.

Dialysis

Data not available

Other Comments

Give deep IM injection or IV at a rate not to exceed 25 mg/min.

Phenylketonurics should be advised that some OTC products may contain phenylalanine.

Hide
(web4)