Diphenhydramine, Oral/Injection

What are other names for this medicine?

Type of medicine: antihistamine

Generic and brand names: diphenhydramine, injection; diphenhydramine, oral; AllerMax; Allergy Medication; Banophen; Benadryl; Benadryl Allergy; Benadryl Dye Free; Benadryl Injection; Benadryl Kapseals; Compoz; Diphen AF; Diphenhist; Diphenhydramine 50; Genahist; Nighttime Sleep Aid; Nytol; Quenalin; Q-dryl; Scot-Tussin Allergy DM; Siladryl; Simply Sleep; Sleep-Eze 3; Sominex 2; Tusstat; Twilite (There may be other brand names for this medicine.)

What is this medicine used for?

This medicine is taken by mouth to treat symptoms of colds and allergies such as sneezing, runny nose, watery eyes, itching, and rash.

It may also be used to prevent motion sickness, treat Parkinson's disease, or to help you sleep.

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have:

• an allergy to any medicine
• a stomach ulcer
• asthma or other breathing problems
• glaucoma
• heart disease
• high blood pressure
• kidney disease
• thyroid disease
• trouble urinating or prostate problems

Females of childbearing age: Tell your healthcare provider if you are pregnant or plan to become pregnant. Do not breast-feed while taking this medicine without your healthcare provider's approval.

How do I use it?

Check the label on the medicine for directions about your specific dose. Take this medicine exactly as your healthcare provider prescribes. Do not take more of it or take it more often than prescribed. Taking too much can make you very drowsy and can increase the risk of other side effects.

You may take this medicine with or without food. Taking it with meals may lessen the chance the drug will upset your stomach.

This medicine may come in different forms. If you have extended-release tablets, do not break, crush, or chew them. Swallow them whole. Ask your pharmacist if you have the extended-release tablets. If you are using the syrup, measure the correct dose with a special dose-measuring spoon or cup.

Injections of this medicine will be given by a healthcare provider.

You can buy some forms of this medicine without a prescription. Follow the directions on the package exactly.

What if I miss a dose?

If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. Do not take double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

If you or anyone else has intentionally taken too much of this medicine, call 911 or go to the emergency room right away. If you pass out, have seizures, weakness or confusion, or have trouble breathing, call 911. If you think that you or anyone else may have taken too much of this medicine, call the poison control center. Do this even if there are no signs of discomfort or poisoning. The poison control center number is 800-222-1222.

Symptoms of an acute overdose may include: slow heartbeat, weakness, chest pain, shortness of breath, lightheadedness, fainting.

What should I watch out for?

This medicine may make you dizzy or drowsy. It may be best to take it at bedtime. When taken at bedtime, you may still be drowsy the next day. Do not drive or operate machinery unless you are fully alert.

Antihistamines increase the effects of alcohol and other drugs that slow down the nervous system. Do not drink alcohol or take other medicines unless your healthcare provider approves.

This medicine may make your skin more sensitive to the sun, which may lead to painful sunburns. While you are taking this medicine, avoid long exposure to the sun. Wear protective clothing, a hat, and sunscreen lotion when you need to be outdoors. Do not use a sunlamp. If you get a severe sunburn, contact your healthcare provider right away.

Adults over the age of 65 may be at greater risk for side effects. Talk with your healthcare provider about this.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Life-threatening (Report these to your healthcare provider right away. If you cannot reach your healthcare provider right away, get emergency medical care or call 911 for help): Allergic reaction (hives; itching; rash; trouble breathing; tightness in your chest; swelling of your lips, tongue, and throat); seizures.

Serious (report these to your doctor right away): Unusual weakness, sore throat, unusual bleeding or bruising, trouble urinating, irregular or pounding heartbeat, chest pain.

Other: Drowsiness, dizziness, heavier phlegm, heartburn, nausea, vomiting, dry mouth, headache, nervousness, confusion, blurred vision.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods, may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

• antiseizure medicines such as carbamazepine (Tegretol), primidone (Mysoline), gabapentin (Neurontin), felbamate (Felbatol), lamotrigine (Lamictal), levetiracetam (Keppra), topiramate (Topamax), valproic acid (Depacon, Depakene, Depakote), oxcarbazepine (Trileptal), tiagabine (Gabitril), and phenytoin (Dilantin)
• anticholinergic medicines such as benztropine (Cogentin), dicyclomine (Bentyl), atropine sulfate, belladonna, propantheline (Pro-Banthine), methscopolamine (Pamine), l-hyoscyamine (Levsin, Levsinex), amantadine (Symmetrel), procyclidine (Kemadrin), and trihexyphenidyl
• herbal remedies such as St. John's wort, valerian, kava, gotu kola, capsicum, Siberian ginseng, German chamomile, goldenseal, melatonin, and SAMe
• MAO inhibitor antidepressants such as isocarboxazid (Marplan), phenelzine (Nardil), and tranylcypromine (Parnate) (Do not take an MAO inhibitor and this medicine within 14 days of each other.)
• muscle relaxants such as tizanidine (Zanaflex), cyclobenzaprine (Flexeril), carisoprodol (Soma), methocarbamol (Robaxin), dantrolene Dantrium), and baclofen (Lioresal)
• narcotic analgesics (painkillers) such as codeine, hydrocodone (Vicodin, Lortab), oxycodone (Percocet, Tylox, OxyContin), propoxyphene (Darvocet N-100), meperidine (Demerol), and fentanyl (Duragesic, Actiq)
• other allergy, cough, or cold medicines that contain an antihistamine, including products used on the skin
• sleeping pills such as phenobarbital (Solfoton), amobarbital (Amytal), zolpidem (Ambien), triazolam (Halcion), butabarbital (Butisol), temazepam (Restoril), eszopiclone (Lunesta), and zaleplon (Sonata)
• tranquilizers such as diazepam (Valium), meprobamate (Equanil), chlordiazepoxide (Librium), alprazolam (Xanax), and lorazepam (Ativan)
• tricyclic antidepressants such as amitriptyline, nortriptyline (Pamelor), imipramine (Tofranil), and doxepin (Sinequan)

Do not drink alcohol while taking this medicine.

Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.

This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.