Diphenhydramine Dosage

Medically reviewed by Drugs.com. Last updated on Aug 1, 2023.

Usual Adult Dose for Extrapyramidal Reaction

Oral: 25 to 50 mg orally 3 to 4 times a day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required

• Maximum dose: 400 mg/day

Comment:

• IV injection rates should not exceed 25 mg/min.

Uses:

• Parkinsonism of the elderly who are unable to tolerate more potent agents
• Mild cases of parkinsonism in other age groups
• Other cases of parkinsonism in combination with centrally acting anticholinergic agents

Usual Adult Dose for Insomnia

Diphenhydramine Citrate: 76 mg orally once a day at bedtime

Diphenhydramine Hydrochloride: 50 mg orally once a day at bedtime

Comment:

• Patients should contact their healthcare provider if symptoms of insomnia persist for more than 2 weeks while receiving treatment.

Uses:

• As a nighttime sleep aid
• To reduce difficulty falling asleep
• Relief of occasional sleeplessness

Usual Adult Dose for Motion Sickness

Oral:

• Prescription formulations: 25 to 50 mg orally 3 to 4 times a day, with the first dose given 30 minutes before exposure to motion and repeated before meals and upon retiring throughout the duration of the journey.

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required

• Maximum dose: 400 mg/day

Comment:

• IV injection rates should not exceed 25 mg/min.

Use:

• Active and prophylactic treatment of motion sickness

Usual Adult Dose for Allergic Rhinitis

Oral:
Diphenhydramine Citrate: 38 to 76 mg orally every 4 to 6 hours as needed

• Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride: 25 to 50 mg orally every 4 to 6 hours as needed

• Maximum dose: 300 mg/day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required

• Maximum dose: 400 mg/day

Comment:

• IV injection rates should not exceed 25 mg/min.

Uses:

• Allergic conjunctivitis due to foods
• Mild, uncomplicated allergic skin manifestations of urticaria and angioedema
• Amelioration of allergic reactions to blood or plasma
• Dermatographism
• Therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after acute manifestations have been controlled
• Temporary relief of runny nose, itchy, watery eyes, sneezing, and itching of the nose/throat due to hay fever or other upper respiratory allergies
• Temporarily relieves runny nose and sneezing due to the common cold

Usual Adult Dose for Cold Symptoms

Oral:
Diphenhydramine Citrate: 38 to 76 mg orally every 4 to 6 hours as needed

• Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride: 25 to 50 mg orally every 4 to 6 hours as needed

• Maximum dose: 300 mg/day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required

• Maximum dose: 400 mg/day

Comment:

• IV injection rates should not exceed 25 mg/min.

Uses:

• Allergic conjunctivitis due to foods
• Mild, uncomplicated allergic skin manifestations of urticaria and angioedema
• Amelioration of allergic reactions to blood or plasma
• Dermatographism
• Therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after acute manifestations have been controlled
• Temporary relief of runny nose, itchy, watery eyes, sneezing, and itching of the nose/throat due to hay fever or other upper respiratory allergies
• Temporarily relieves runny nose and sneezing due to the common cold

Usual Adult Dose for Pruritus

Oral:
Diphenhydramine Citrate: 38 to 76 mg orally every 4 to 6 hours as needed

• Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride: 25 to 50 mg orally every 4 to 6 hours as needed

• Maximum dose: 300 mg/day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required

• Maximum dose: 400 mg/day

Comment:

• IV injection rates should not exceed 25 mg/min.

Uses:

• Allergic conjunctivitis due to foods
• Mild, uncomplicated allergic skin manifestations of urticaria and angioedema
• Amelioration of allergic reactions to blood or plasma
• Dermatographism
• Therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after acute manifestations have been controlled
• Temporary relief of runny nose, itchy, watery eyes, sneezing, and itching of the nose/throat due to hay fever or other upper respiratory allergies
• Temporarily relieves runny nose and sneezing due to the common cold

Usual Adult Dose for Urticaria

Oral:
Diphenhydramine Citrate: 38 to 76 mg orally every 4 to 6 hours as needed

• Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride: 25 to 50 mg orally every 4 to 6 hours as needed

• Maximum dose: 300 mg/day

Parenteral: 10 to 50 mg deep IM or IV as needed, and may increase to 100 mg if required

• Maximum dose: 400 mg/day

Comment:

• IV injection rates should not exceed 25 mg/min.

Uses:

• Allergic conjunctivitis due to foods
• Mild, uncomplicated allergic skin manifestations of urticaria and angioedema
• Amelioration of allergic reactions to blood or plasma
• Dermatographism
• Therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after acute manifestations have been controlled
• Temporary relief of runny nose, itchy, watery eyes, sneezing, and itching of the nose/throat due to hay fever or other upper respiratory allergies
• Temporarily relieves runny nose and sneezing due to the common cold

Usual Pediatric Dose for Allergic Rhinitis

Prescription formulations:
1 month and older:
Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used

• Maximum dose: 300 mg/day

Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day

• Maximum dose: 300 mg/day

Oral Over-the-Counter (OTC) formulations:
Diphenhydramine Citrate:
6 to 12 years: 19 to 38 mg orally every 4 to 6 hours as needed

• Maximum dose: 228 mg/day

12 years and older: 38 to 76 mg orally every 4 to 6 hours as needed

• Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride:
2 to 6 years: 6.25 mg orally every 4 to 6 hours as needed

• Maximum dose: 37.5 mg/day

6 to 12 years: 12.5 to 25 mg orally every 4 to 6 hours as needed

• Maximum dose: 150 mg/day

12 years and older: 25 to 50 mg orally every 4 to 6 hours as needed

• Maximum dose: 300 mg/day

Comments:

• IV injection rates should not exceed 25 mg/min.
• To prevent motion sickness, the first dose should be given 30 minutes before exposure to motion and should be repeated before meals and upon retiring throughout the duration of the journey.

Uses:

• Active and prophylactic treatment of motion sickness
• Temporary relief of runny nose, itchy, watery eyes, sneezing, and itching of the nose/throat due to hay fever or other upper respiratory allergies
• Temporarily relieves runny nose and sneezing due to the common cold

Usual Pediatric Dose for Cold Symptoms

Prescription formulations:
1 month and older:
Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used

• Maximum dose: 300 mg/day

Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day

• Maximum dose: 300 mg/day

Oral Over-the-Counter (OTC) formulations:
Diphenhydramine Citrate:
6 to 12 years: 19 to 38 mg orally every 4 to 6 hours as needed

• Maximum dose: 228 mg/day

12 years and older: 38 to 76 mg orally every 4 to 6 hours as needed

• Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride:
2 to 6 years: 6.25 mg orally every 4 to 6 hours as needed

• Maximum dose: 37.5 mg/day

6 to 12 years: 12.5 to 25 mg orally every 4 to 6 hours as needed

• Maximum dose: 150 mg/day

12 years and older: 25 to 50 mg orally every 4 to 6 hours as needed

• Maximum dose: 300 mg/day

Comments:

• IV injection rates should not exceed 25 mg/min.
• To prevent motion sickness, the first dose should be given 30 minutes before exposure to motion and should be repeated before meals and upon retiring throughout the duration of the journey.

Uses:

• Active and prophylactic treatment of motion sickness
• Temporary relief of runny nose, itchy, watery eyes, sneezing, and itching of the nose/throat due to hay fever or other upper respiratory allergies
• Temporarily relieves runny nose and sneezing due to the common cold

Usual Pediatric Dose for Motion Sickness

Prescription formulations:
1 month and older:
Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used

• Maximum dose: 300 mg/day

Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day

• Maximum dose: 300 mg/day

Oral Over-the-Counter (OTC) formulations:
Diphenhydramine Citrate:
6 to 12 years: 19 to 38 mg orally every 4 to 6 hours as needed

• Maximum dose: 228 mg/day

12 years and older: 38 to 76 mg orally every 4 to 6 hours as needed

• Maximum dose: 456 mg/day

Diphenhydramine Hydrochloride:
2 to 6 years: 6.25 mg orally every 4 to 6 hours as needed

• Maximum dose: 37.5 mg/day

6 to 12 years: 12.5 to 25 mg orally every 4 to 6 hours as needed

• Maximum dose: 150 mg/day

12 years and older: 25 to 50 mg orally every 4 to 6 hours as needed

• Maximum dose: 300 mg/day

Comments:

• IV injection rates should not exceed 25 mg/min.
• To prevent motion sickness, the first dose should be given 30 minutes before exposure to motion and should be repeated before meals and upon retiring throughout the duration of the journey.

Uses:

• Active and prophylactic treatment of motion sickness
• Temporary relief of runny nose, itchy, watery eyes, sneezing, and itching of the nose/throat due to hay fever or other upper respiratory allergies
• Temporarily relieves runny nose and sneezing due to the common cold

Usual Pediatric Dose for Insomnia

12 years and older:

• Diphenhydramine citrate: 76 mg orally once a day at bedtime
• Diphenhydramine hydrochloride: 50 mg orally once a day at bedtime

Comment:

• Patients should contact their healthcare provider if symptoms of insomnia persist for more than 2 weeks while receiving treatment.

Uses:

• As a nighttime sleep aid
• To reduce difficulty falling asleep
• Relief of occasional sleeplessness

Usual Pediatric Dose for Extrapyramidal Reaction

1 month and older:
Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used

• Maximum dose: 300 mg/day

Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day

• Maximum dose: 300 mg/day

Comment:

• IV injection rates should not exceed 25 mg/min.

Uses:

• Mild cases of parkinsonism
• Other cases of parkinsonism, including drug-induced, in combination with centrally acting anticholinergic agents

Usual Pediatric Dose for Allergic Reaction

1 month and older:
Oral: 12.5 to 25 mg orally 3 to 4 times a day; alternatively, weight-based dosing of 5 mg/kg orally per day OR body surface area dosing of 150 mg/m2 orally per day may be used

• Maximum dose: 300 mg/day

Parenteral: 1.25 mg/kg deep IM or IV 4 times a day OR 37.5 mg/m2 deep IM or IV 4 times a day

• Maximum dose: 300 mg/day

Comment:

• IV injection rates should not exceed 25 mg/min.

Uses:

• Allergic conjunctivitis due to foods
• Mild, uncomplicated allergic skin manifestations of urticaria and angioedema
• Amelioration of allergic reactions to blood or plasma
• Dermatographism
• Therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after acute manifestations have been controlled

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Precautions

Safety and efficacy have not been established in newborn or premature infants.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

• Chewable tablets: Tablets should be chewed or allowed to dissolve on the tongue before swallowing.
• Oral powder: Oral powder formulations may be taken with or without water. Patients should avoid dividing the packet in half.

Storage requirements:

• Film-coated tablets: Avoid excessive heat (e.g., 37.8C) or humidity.
• Oral capsules and dissolving tablets: Avoid high humidity and protect from light.
• Oral liquid: Do not refrigerate. Store in the outer carton to protect from light when not in use.
• Parenteral formulations: Protect from light and freezing.

General:

• This drug reduces sleep onset and increases the depth and quality of sleep.
• Parenteral formulations should be reserved for situations where oral treatment is impossible or contraindicated.

Patient advice:

• This drug may cause drowsiness; patients should be told to avoid driving or operating machinery if they feel drowsy or dizzy.

Frequently asked questions

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer