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diphenhydramine

Pronunciation

Generic Name: diphenhydramine (DYE fen HYE dra meen)
Brand Name: Allergy Relief (Diphenhydramine HCl), Allermax, Banophen, Benadryl, Compoz Nighttime Sleep Aid, Diphedryl, Diphenhist, Dytuss, Nytol QuickCaps, PediaCare Children's Allergy, Q-Dryl, QlearQuil Nightitme Allergy Relief, Quenalin, Scot-Tussin Allergy Relief Formula, Siladryl Allergy, Silphen Cough, Simply Sleep, Sleepinal, Sominex, Tranquil, Twilite, Unisom Sleepgels Maximum Strength, Valu-Dryl, Vanamine PD, Z-Sleep, ZzzQuil, ...show all 91 brand names

What is diphenhydramine?

Diphenhydramine is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Diphenhydramine is used to treat sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms.

Diphenhydramine is also used to treat motion sickness, to induce sleep, and to treat certain symptoms of Parkinson's disease.

Diphenhydramine may also be used for purposes not listed in this medication guide.

What is the most important information I should know about diphenhydramine?

You should not use antihistamine medication to make a child sleepy.

What should I discuss with my healthcare provider before taking diphenhydramine?

You should not use diphenhydramine if you are allergic to it.

Ask a doctor or pharmacist if it is safe for you to take this medicine if you have other medical conditions, especially:

  • blockage in your digestive tract (stomach or intestines);

  • bladder obstruction or other urination problems;

  • a colostomy or ileostomy;

  • liver or kidney disease;

  • asthma, chronic obstructive pulmonary disease (COPD), or other breathing disorder;

  • cough with mucus, or cough caused by smoking, emphysema, or chronic bronchitis;

  • heart disease, low blood pressure;

  • glaucoma;

  • a thyroid disorder; or

  • if you take potassium (Cytra, Epiklor, K-Lyte, K-Phos, Kaon, Klor-Con, Polycitra, Urocit-K).

It is not known whether diphenhydramine will harm an unborn baby. Ask a doctor before using this medicine if you are pregnant.

Diphenhydramine can pass into breast milk and may harm a nursing baby. Antihistamines may also slow breast milk production. Ask a doctor before using this medicine if you are breast-feeding.

Older adults may be more likely to have side effects from this medicine.

How should I take diphenhydramine?

Use exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended. Cold or allergy medicine is usually taken only for a short time until your symptoms clear up.

Do not give this medication to a child younger than 2 years old. Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children.

You should not use antihistamine medication to make a child sleepy.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

For motion sickness, take diphenhydramine 30 minutes before you will be in a situation that causes you motion sickness (such as a long car ride, airplane or boat travel, amusement park rides, etc). Continue taking diphenhydramine with meals and at bedtime for the rest of the time you will be in a motion-sickness situation.

As a sleep aid, take diphenhydramine within 30 minutes before bedtime.

Call your doctor if your symptoms do not improve after 7 days of treatment, or if you have a fever with a headache, cough, or skin rash.

This medication can affect the results of allergy skin tests. Tell any doctor who treats you that you are using diphenhydramine.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Since diphenhydramine is used when needed, you may not be on a dosing schedule. If you are on a schedule, use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking diphenhydramine?

This medication may cause blurred vision and may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.

Drinking alcohol can increase certain side effects of diphenhydramine.

Ask a doctor or pharmacist before using any other cold, cough, allergy, or sleep medicine. Antihistamines are contained in many combination medicines. Taking certain products together can cause you to get too much of this type of medicine. Check the label to see if a medicine contains an antihistamine.

Diphenhydramine side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using diphenhydramine and call your doctor at once if you have:

  • pounding heartbeats or fluttering in your chest;

  • painful or difficult urination;

  • little or no urinating;

  • confusion, feeling like you might pass out; or

  • tightness in your neck or jaw, uncontrollable movements of your tongue.

Common side effects may include:

  • dizziness, drowsiness, loss of coordination;

  • dry mouth, nose, or throat;

  • constipation, upset stomach;

  • dry eyes, blurred vision; or

  • day-time drowsiness or "hangover" feeling after night-time use.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

Diphenhydramine dosing information

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

What other drugs will affect diphenhydramine?

Ask a doctor or pharmacist before using this medicine if you are also using any other drugs, including prescription and over-the-counter medicines, vitamins, and herbal products. Some medicines can cause unwanted or dangerous effects when used together. Not all possible interactions are listed in this medication guide.

Taking this medicine with other drugs that make you sleepy or slow your breathing can worsen these effects. Ask your doctor before taking diphenhydramine with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Where can I get more information?

  • Your pharmacist can provide more information about diphenhydramine.
  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2012 Cerner Multum, Inc. Version: 6.01.

Date modified: July 02, 2017
Last reviewed: April 17, 2017

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