What is this medicine?
DIPHENHYDRAMINE (dye fen HYE dra meen) is an antihistamine. It is used to treat the symptoms of an allergic reaction and motion sickness. It is also used to treat Parkinson's disease.
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 health care provider before I take this medicine?
They need to know if you have any of these conditions:
- asthma or lung disease
- 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 medicines foods, dyes, or preservatives
- pregnant or trying to get pregnant
How should I use this medicine?
This medicine is for injection into a vein or a muscle. It is usually given by a health care professional in a hospital or clinic setting.
If you get this medicine at home, you will be taught how to prepare and give this medicine. Use exactly as directed. Take your medicine at regular intervals. Do not take your medicine 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 healthcare provider to get one.
Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for selected conditions, precautions do apply. This medicine 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 medicine?
Do not take this medicine with any of the following medications:
- MAOIs like Carbex, Eldepryl, Marplan, Nardil, and Parnate
This medicine may also interact with the following medications:
- barbiturates, like phenobarbital
- medicines for bladder spasm like oxybutynin, tolterodine
- medicines for blood pressure
- medicines for depression, anxiety, or psychotic disturbances
- medicines for movement abnormalities or Parkinson's disease
- medicines for sleep
- other medicines for cold, cough or allergy
- some medicines 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 medicine?
Your condition will be monitored carefully while you are receiving this medicine. Tell your doctor or healthcare professional 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 medicine 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 medicine. Avoid alcoholic drinks.
Your mouth may get dry. Chewing sugarless gum or sucking hard candy, and drinking plenty of water may help. Contact your doctor if the problem does not go away or is severe.
What side effects may I notice from receiving this medicine?
Side effects that you should report to your doctor or health care professional as soon as possible:
- allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
- breathing problems
- changes in vision
- confused, agitated, nervous
- irregular or fast heartbeat
- low blood pressure
- trouble passing urine
- unusual bleeding or bruising
- unusually weak or tired
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
- constipation, diarrhea
- loss of appetite
- stomach upset, vomiting
- thick mucous
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 medicine?
Keep out of the reach of children.
If you are using this medicine at home, you will be instructed on how to store this medicine. Throw away any unused medicine 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.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy