What is this medication?

DIPHENHYDRAMINE (dye fen HYE dra meen) treats the symptoms of allergic reactions. It may also be used to prevent and treat motion sickness or the symptoms of Parkinson disease. It works by blocking histamine, a substance released by the body during an allergic reaction. It belongs to a group of medications called antihistamines.

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

COMMON BRAND NAME(S): Benadryl

What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

• Asthma or lung disease
• Glaucoma
• High blood pressure or heart disease
• Liver disease
• Pain or difficulty passing urine
• Prostate trouble
• Ulcers or other stomach problems
• An unusual or allergic reaction to diphenhydramine, antihistamines, other medications foods, dyes, or preservatives
• Pregnant or trying to get pregnant
• Breast-feeding

How should I use this medication?

This medication is for injection into a vein or a muscle. It is usually given in a hospital or clinic.

If you get this medication at home, you will be taught how to prepare and give this medication. Use exactly as directed. Take your medication at regular intervals. Do not take your medication more often than directed.

It is important that you put your used needles and syringes in a special sharps container. Do not put them in a trash can. If you do not have a sharps container, call your pharmacist or care team to get one.

Talk to your care team regarding the use of this medication in children. While this medication may be prescribed for selected conditions, precautions do apply. This medication is not approved for use in newborns and premature babies.

Patients over 60 years old may have a stronger reaction and need a smaller dose.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What may interact with this medication?

Do not take this medication with any of the following:

• MAOIs like Carbex, Eldepryl, Marplan, Nardil, and Parnate

This medication may also interact with the following:

• Alcohol
• Barbiturates, like phenobarbital
• Medications for bladder spasm like oxybutynin, tolterodine
• Medications for blood pressure
• Medications for depression, anxiety, or psychotic disturbances
• Medications for movement abnormalities or Parkinson disease
• Medications for sleep
• Other medications for cold, cough or allergy
• Some medications for the stomach like chlordiazepoxide, dicyclomine

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medication?

Your condition will be monitored carefully while you are receiving this medication. Tell your care team if your symptoms do not start to get better or if they get worse.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medication affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells. Alcohol may interfere with the effect of this medication. Avoid alcoholic drinks.

Your mouth may get dry. Chewing sugarless gum or sucking hard candy, and drinking plenty of water may help. Contact your care team if the problem does not go away or is severe.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible:

• Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
• Sudden eye pain or change in vision such as blurry vision, seeing halos around lights, vision loss
• Trouble passing urine

Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):

• Constipation
• Drowsiness
• Dry mouth
• Headache
• Upset stomach

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medication?

Keep out of the reach of children and pets.

If you are using this medication at home, you will be instructed on how to store this medication. Throw away any unused medication after the expiration date on the label.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.