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Allergy (Diphenhydramine HCl)

Generic name: diphenhydramine [ DYE-fen-HYE-dra-meen ]
Brand names: Allergy (Diphenhydramine HCl), Allergy Relief (Diphenhydramine HCl), Banophen, Benadryl, Benadryl Allergy, ... show all 41 brands
Drug classes: Anticholinergic antiemetics, Anticholinergic antiparkinson agents, Antihistamines, Miscellaneous anxiolytics, sedatives and hypnotics

Medically reviewed by Drugs.com on Aug 1, 2023. Written by Cerner Multum.

What is Allergy (Diphenhydramine HCl)?

Allergy (Diphenhydramine HCl) is an antihistamine that is used to treat sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms.

Allergy (Diphenhydramine HCl) is also used to treat motion sickness, to induce sleep, and to treat certain symptoms of Parkinson's disease. Allergy (Diphenhydramine HCl) sleep aid medicine is not for use in children younger than 12 years old.

There are many brands and forms of Allergy (Diphenhydramine HCl) available. Not all brands are listed on this leaflet.

Allergy (Diphenhydramine HCl) may also be used for purposes not listed in this medication guide.

Allergy (Diphenhydramine HCl) 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 Allergy (Diphenhydramine HCl) and call your doctor at once if you have:

Side effects such as dry mouth, constipation, and confusion may be more likely in older adults.

Common side effects of Allergy (Diphenhydramine HCl) may include:

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.

Diphenhydramine side effects (more detail)

Warnings

Use Allergy (Allergy (Diphenhydramine HCl) HCl) exactly as directed. Taking too much Allergy (Diphenhydramine HCl) can lead to serious heart problems, seizures, coma, or death.

Do not use this medicine to make a child sleepy. Allergy (Diphenhydramine HCl) sleep aid medicine is not for use in children younger than 12 years old.

Before taking this medicine

You should not use Allergy (Diphenhydramine HCl) if you are allergic to it.

Ask a doctor or pharmacist if this medicine is safe to use if you have ever had:

Ask a doctor before using this medicine if you are pregnant or breastfeeding. Allergy (Diphenhydramine HCl) may slow breast milk production.

How should I take Allergy (Diphenhydramine HCl)?

Use exactly as directed on the label, or as prescribed by your doctor. Allergy (Diphenhydramine HCl) is only for short-term use until your symptoms clear up.

Taking too much Allergy (Diphenhydramine HCl) can lead to serious heart problems, seizures, coma, or death.

Always follow directions on the medicine label about giving Allergy (Diphenhydramine HCl) to a child. Do not use the medicine only to make a child sleepy. Death can occur from the misuse of antihistamines in very young children.

For motion sickness, take Allergy (Diphenhydramine HCl) 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 Allergy (Diphenhydramine HCl) with meals and at bedtime for the rest of the time you will be in a motion-sickness situation.

As a sleep aid, take Allergy (Diphenhydramine HCl) within 30 minutes before bedtime.

You must chew the chewable tablet before you swallow it.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Remove an orally disintegrating tablet from the package only when you are ready to take the medicine. Place the tablet in your mouth and allow it to dissolve, without chewing. Swallow several times as the tablet dissolves.

Call your doctor if the condition you are treating with Allergy (Diphenhydramine HCl) does not improve, or if you have a fever with a headache, cough, or skin rash.

Do not use Allergy (Diphenhydramine HCl) for longer than 2 weeks to treat sleep problems, or longer than 7 days to treat cold or allergy symptoms.

Allergy (Allergy (Diphenhydramine HCl) HCl) can affect the results of allergy skin tests. Tell any doctor who treats you that you are using Allergy (Diphenhydramine HCl).

Store at room temperature away from moisture and heat.

Detailed Diphenhydramine dosage information

Quviviq, acetaminophen, prednisone, ibuprofen, hydroxyzine, ondansetron, clonazepam, fluticasone nasal, lorazepam, cetirizine

What happens if I miss a dose?

Since Allergy (Allergy (Diphenhydramine HCl) HCl) is used when needed, you may not be on a dosing schedule. Skip any missed dose if it's almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of Allergy (Diphenhydramine HCl) can be fatal.

Overdose symptoms may include vomiting, confusion, severe drowsiness, ringing in your ears, no urination, very dry eyes and mouth, dilated pupils, fast heartbeats, tremor, agitation, hallucinations, or seizure.

What should I avoid while taking Allergy (Diphenhydramine HCl)?

Avoid driving or hazardous activity until you know how Allergy (Allergy (Diphenhydramine HCl) HCl) will affect you. Your reactions could be impaired.

Drinking alcohol can increase certain side effects of Allergy (Diphenhydramine HCl).

Ask a doctor or pharmacist before using any other medicine that may contain Allergy (Diphenhydramine HCl). This includes medicines for sleep, cold/allergy symptoms, or anti-itch medicine used on the skin. Using too much Allergy (Diphenhydramine HCl) may lead to a fatal overdose.

What other drugs will affect Allergy (Diphenhydramine HCl)?

Ask a doctor or pharmacist before using Allergy (Diphenhydramine HCl) with any other medicines, especially drugs that can cause drowsiness (such as opioid medication, sleep medicine, a muscle relaxer, or medicine for anxiety or seizures). Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

Diphenhydramine drug interactions (more detail)

Does diphenhydramine interact with my other drugs?

Enter other medications to view a detailed interaction report.

Popular FAQ

What is the max dose of diphenhydramine for adults?

The maximum oral dose of diphenhydramine for adults is generally reported as 100mg for a single dose or no more than 300mg in 24 hours, but this can vary depending on what condition diphenhydramine is being used for, the salt of diphenhydramine used (there are two salts available in the US diphenhydramine citrate and diphenhydramine chloride), the age of the person, how much diphenhydramine they have tolerated before, and if they are on any interacting medications. Taking too much diphenhydramine can be fatal. Continue reading

Does Mucinex help with Covid?

Mucinex products do not help to prevent or treat the COVID-19 virus itself, but might help relieve some of the symptoms of COVID, like chest congestion, cough, or headache. Select a product that targets only the symptoms you have. Continue reading

Does diphenhydramine raise blood pressure?

Increased blood pressure is not a typical side effect of diphenhydramine, a first-generation antihistamine that lowers the effects of histamines in your body. However, in rare cases, the drug may cause hypotension, or decreased blood pressure. This side effect is most likely to occur in people who are over the age of 60. Continue reading

Does Benadryl help with or cause anxiety?

One of the most common side effects with Benadryl is drowsiness, but in some people it can have the opposite effect, known as paradoxical excitation. Instead of feeling sleepy,
you may experience excitation, agitation or insomnia (trouble sleeping), which might make your anxiety symptoms feel worse. This may be more common in young children. Continue reading

Can diphenhydramine be used as a sleep aid?

Diphenhydramine can be used as a short-term sleep aid to help ease occasional sleep problems, such as when you have a cold or cough and it is preventing you from falling asleep. Older adults, children under age 16 and pregnant women should avoid taking diphenhydramine, as the risks to these groups may outweigh the benefits. Continue reading

Diphenhydramine Hydrochloride vs Citrate: What's the difference?

The difference between diphenhydramine hydrochloride and diphenhydramine citrate is that the salt used to bind the diphenhydramine, is different. For diphenhydramine hydrochloride the salt is hydrochloride and for diphenhydramine citrate the salt is citrate. This salt can change how quickly and effectively the diphenhydramine dissolves and is absorbed but once it is in the body it has no effect. Essentially 25 mg of diphenhydramine hydrochloride is equivalent to 38 mg of diphenhydramine citrate. Continue reading

View more FAQ

Further information

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.

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

Medical Disclaimer

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