Prescription vs OTC: Prescription by Doctor required

Diphenhydramine, an antihistamine, relieves symptoms of hay fever, allergy, and the common cold. Symptoms may include itching, rash, watery eyes, runny nose, itchy eyes or nose, throat, cough, and sneezing. It also prevents and treats nausea, vomiting, and dizziness caused by motion sickness. It can also help you relax and fall asleep.

Diphenhydramine provides symptomatic relief of allergic symptoms caused by histamine release which include nasal allergies and allergic dermatosis; can be used for mild nighttime sedation; prevention of motion sickness and as an antitussive; has antinauseant and topical anesthetic properties; treatment of antipsychotic-induced extrapyramidal reactions.

You should not use this medication If you have or are:

  • Allergic to it
  • Liver or kidney disease
  • Breathing disorder
  • Blockage in the digestive tract
  • Urinary problems
  • Thyroid disorder or
  • Chronic bronchitis

This drug is available as a tablet, capsule, or liquid form and can be taken with or without food. Your dosage is based on your medical condition, age and response to treatment. To prevent motion sickness or help you sleep, take the dose 30 minutes before travel or bedtime.

Take as directed; do not exceed recommended dose. Avoid use of other depressants, alcohol, or sleep-inducing medications unless approved by prescriber. You may experience drowsiness or dizziness (use caution when driving or engaging in tasks requiring alertness until response to drug is known).

Patient may also experience dry mouth, nausea, or vomiting (frequent small meals, frequent mouth care, chewing gum, or sucking hard candy may help). Report persistent sedation, confusion, or agitation; changes in urinary pattern; blurred vision; sore throat, difficulty breathing, or expectorating (thick secretions); or lack of improvement or worsening or condition.

Diphenhydramine should be protect from light. The following drugs are incompatible with diphenhydramine when mixed in the same syringe: Amobarbital, amphotericin B, cephalothin, diatrizoate, foscarnet, heparin, hydrocortisone, hydroxyzine, pentobarbital, phenobarbital, phenytoin, prochlorperazine, promazine, promethazine, tetracycline, thiopental

Symptoms of overdose include CNS stimulation or depression; overdose may result in death in infants and children. There is no specific treatment for an antihistamine overdose, however, most of its clinical toxicity is due to anticholinergic effects.

Anticholinesterase inhibitors (eg, physostigmine, neostigmine, pyridostigmine, or edrophonium) may be useful by reducing acetylcholinesterase. For anticholinergic overdose with severe life-threatening symptoms, physostigmine 1-2 mg (0.5 mg or 0.02 mg/kg for children) I.V., slowly may be given to reverse these effects.

Information given here is based on the salt content of the medicine. Uses and effects of the medicine may vary from person to person. It is advisable to consult a Internal Medicine Specialist before using this medicine.

The medication can treat the below provided problems:

A patient can suffer from the following side effects:

  • Is It safe with alcohol?

    This medication may cause excessive drowsiness and calmness with alcohol.
  • Are there any pregnancy warnings?

    This medication is highly unsafe to use during pregnancy.
  • Are there any breast-feeding warnings?

    This medication is probably unsafe to use during breastfeeding. Please consult your doctor.
  • Is it safe to drive while on this medicine?

    No data available
  • Does this affect kidney function?

    Contraindicated in patients with severe renal impairment.
  • Does this affect liver function?

    There is no data available. Please consult a doctor before consuming the drug.
  • What is the onset of action?

    The action of this medicine is initiated within 60 minutes after its administration.
  • How long is the duration of effect?

    The drug will remain active for about 4 - 7 hrs.
  • Are there any overdose instructions?

    Seek emergency medical treatment or contact the doctor in case of an overdose.
  • Are there any missed dose instructions?

    If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double the dose.

Below is the list of medicines, which contains Diphenhydramine as ingredient

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This medication is used to treat many of the diseases. It is used against hypersensitive reactions, Parkinson's disease, hypnosis, and also to treat the common cold. It belongs to the H1 antagonist class of medication, thus produce sedative effects on patients. This drug basically acts against free histamine, as it binds to the HA-receptor sites.

Whenever you take more than one medicine, or mix it with certain foods or beverages, you"re at risk of a drug interaction.

  • Interaction with Alcohol

    Additive CNS effects, avoid use.
  • Interaction with Lab Test

    May suppress the wheal and flare reactions to skin test antigens.
  • Interaction with Medicine

    • Therapeutic effects of cholinergic agents (tacrine, donepezil) and neuroleptics may be antagonized.
    • Central and/or peripheral anticholinergic syndrome can occur when administered with amantadine, rimantadine, narcotic analgesics, phenothiazines and other antipsychotics (especially with high anticholinergic activity), tricyclic antidepressants, quinidine and some other antiarrhythmics, and antihistamines.
    • Syrup should not be given to patients taking drugs that can cause disulfiram reactions (ie, metronidazole, chlorpropamide) due to high alcohol content.
  • Interaction with Disease

    Use with caution in patients with angle-closure glaucoma, pyloroduodenal obstruction (including stenotic peptic ulcer), urinary tract obstruction (including bladder neck obstruction and symptomatic prostatic hypertrophy), hyperthyroidism, increased intraocular pressure, and cardiovascular disease (including hypertension and tachycardia). Diphenhydramine has high sedative and anticholinergic properties, so it may not be considered the antihistamine of choice for prolonged use in the elderly. May cause paradoxical excitation in pediatric patients, and can result in hallucinations, coma, and death in overdose. Some preparations contain sodium bisulfite; syrup formulations may contain alcohol.

Ques: What is Diphenhydramine?

Ans: This medication is an antihistamine, relieves symptoms of hay fever, allergy and common cold.

Ques: How long do I need to use Diphenhydramine before I see improvement in my condition?

Ans: This medication is to be taken till the time you see an improvement in your health conditions.

Ques: At what frequency do I need to use Diphenhydramine?

Ans: Adults and children over 12 years: 1 or 2 tablets three or four times a day or as prescribed by a doctor

Ques: Should I use Diphenhydramine empty stomach, before food or after food?

Ans: This medication should be taken after food in a prescribed dosage.

Ques: What are the instructions for the storage and disposal of Diphenhydramine?

Ans: This medication should be kept in a cool dry place and in its original packaging. Make sure this medication remains unreachable to children and pets.

Ques: What is Diphenhydramine used for?

Ans: Diphenhydramine is used in the treatment of nasal allergy symptoms, motion sickness and insomnia.

Ques: How long does Diphenhydramine take to work?

Ans: Usually, Diphenhydramine starts working soon after taking it. However, it may take some days to kill all the harmful bacteria and make you feel better.

Ques: What if I don't get better after using Diphenhydramine?

Ans: Inform your doctor if you don't feel better after finishing the full course of treatment. Also, inform him if your symptoms are getting worse while using this medicine.

Ques: Is Diphenhydramine for infants?

Ans: No, it should not be given to infants. Always follow doctor's advice regarding its use.

Ques: Does Diphenhydramine make you sleepy/drowsy?

Ans: Yes, it makes you sleepy/drowsy. Always follow doctor's advice regarding its use.
Disclaimer: The information produced here is best of our knowledge and experience and we have tried our best to make it as accurate and up-to-date as possible, but we would like to request that it should not be treated as a substitute for professional advice, diagnosis or treatment.

Lybrate is a medium to provide our audience with the common information on medicines and does not guarantee its accuracy or exhaustiveness. Even if there is no mention of a warning for any drug or combination, it never means that we are claiming that the drug or combination is safe for consumption without any proper consultation with an expert.

Lybrate does not take responsibility for any aspect of medicines or treatments. If you have any doubts about your medication, we strongly recommend you to see a doctor immediately.

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Content Details
Written By
PhD (Pharmacology) Pursuing, M.Pharma (Pharmacology), B.Pharma - Certificate in Nutrition and Child Care
Reviewed By
MBBS, Master in Healthcare Administration, Diploma in Occupational Health
General Physician
Table of Content
About Diphenhydramine
What are the uses of Diphenhydramine
What are the contraindications of Diphenhydramine ?
What are the side effects of Diphenhydramine ?
Key highlights of Diphenhydramine
What are the dosage instructions?
Medicines containing Diphenhydramine
How does this medication work?
What are the interactions of Diphenhydramine ?
FAQs about Diphenhydramine