Diphenhydramine

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Update Date 14/08/2020 . 5 mins read
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Uses

What is diphenhydramine used for?

Diphenhydramine is a first-generation antihistamine. It is mainly used to treat symptoms of allergies which commonly include itchiness, runny nose, watery eyes, and sneezing. Another effect of diphenhydramine includes sedation which is useful for treating motion sickness and insomnia.

How should I take diphenhydramine?

Use diphenhydramine as ordered by your doctor. Read all information given to you. Follow all instructions closely. Take with or without food. Take with food if it causes an upset stomach. Take this medicine at bedtime.

How do I store diphenhydramine?

Diphenhydramine is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store diphenhydramine in the bathroom or the freezer.

There may be different brands of diphenhydramine that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush diphenhydramine down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed.

Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using diphenhydramine?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of the active or inactive ingredients of diphenhydramine or other medications.
  • You have any other illnesses, disorders, or medical conditions.

Tell all of your health care providers that you take diphenhydramine. This includes your doctors, nurses, pharmacists, and dentists.

Avoid driving and doing other tasks or actions that call for you to be alert until you see how diphenhydramine affects you.

Do not use with other products that contain diphenhydramine or other antihistamines and sedatives.

If you are 60 or older, use diphenhydramine with care. You may experience more side effects.

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using diphenhydramine during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking diphenhydramine. Diphenhydramine is a pregnancy risk category B, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Side effects

What side effects can occur from diphenhydramine?

Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Very bad dizziness or passing out.
  • Change in balance.
  • Feeling sleepy.
  • Dizziness
  • Thickening of mucus in nose or throat.
  • Feeling nervous and excitable.
  • Upset stomach or throwing up.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with diphenhydramine?

Diphenhydramine may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects.

To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with diphenhydramine?

Do not take this drug with alcohol or alcohol-containing medications. It may increase the severity of drowsiness and CNS depression.

Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with diphenhydramine?

Diphenhydramine may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works.

It is important to always let your doctor and pharmacist know all the health conditions you currently have.

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Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using diphenhydramine.

What is the dose of diphenhydramine for an adult?

For allergies & motion sickness

Oral

Take 25-50 mg 3-4 times per day. The maximum dose is 300 mg per day.

If used to prevent motion sickness, administer the drug 30 minutes before traveling or other activities.

IV/IM

Give 10-50 mg (up to 100 mg, if needed) via IV injection at a rate not exceeding 25 mg/min or via deep IM injection. The maximum daily dose is 400 mg.

If used to prevent motion sickness, administer the drug 30 minutes before traveling or other activities.

Topical

Apply a thin layer of cream to the affected areas 1-2 times per day. Do not use for more than 3 days.

For short-term treatment of insomnia

Oral

Take 50 mg, 30 minutes before bedtime.

For Parkinson’s disease

IV/IM

Give 10-50 mg (up to 100 mg, if needed) via IV injection at a rate not exceeding 25 mg/min or via deep IM injection. The maximum daily dose is 400 mg.

*Note: only use the parenteral route when oral therapy is impossible or contraindicated.

What is the dose of diphenhydramine for a child?

For allergies & motion sickness

Oral

Age 2-6 years: give 6.25 mg every 4-6 hours.

Age 6-12 years: give 12.5-25 mg every 4-6 hours.

Age >12 years: same as the adult dose.

IV/IM

Give 5 mg/kg via IV injection at a rate of 25 mg/min or deep IM injection in 4 divided doses. The maximum daily dose is 300 mg.

If used to prevent motion sickness, administer the drug 30 minutes before traveling or other activities.

Topical

For children 2 years and above: same as adult dose.

How is diphenhydramine available?

Diphenhydramine is available in the following brands, dosage forms, and strengths:

  • Capsule
  • Tablet

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of diphenhydramine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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