Highlights for diphenhydramine
diphenhydramine Side Effects
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
- changes in vision
- confused, agitated, or nervous
- fast, irregular heartbeat
- trouble passing urine or change in the amount of 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 mucus
diphenhydramine May Interact with Other Medications
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
How to Use diphenhydramine
Take this medicine by mouth with a full glass of water. Follow the directions on the prescription label. Use a specially marked spoon or container to measure your medicine. Household spoons are not accurate. Take your medicine at regular intervals. Do not take it more often than directed.
Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.
Patients over 65 years old may have a stronger reaction and need a smaller dose.
They need to know if you have any of these conditions:
- high blood pressure or heart disease
- liver disease
- lung or breathing disease, like asthma
- pain or trouble passing urine
- prostate trouble
- ulcers or other stomach problems
- an unusual or allergic reaction to diphenhydramine, other medicines foods, dyes, or preservatives such as sulfites
- pregnant or trying to get pregnant
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.
Visit your doctor or health care professional for regular check ups. Tell your doctor or health care professional if your symptoms do not start to get better or if they get worse.
If you are diabetic use a sugar-free form of this medicine.
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.
This medicine may cause dry eyes and blurred vision. If you wear contact lenses you may feel some discomfort. Lubricating drops may help. See your eye doctor if the problem does not go away or is severe.
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.
Keep out of the reach of children.
Store at room temperature, between 15 and 30 degrees C (59 and 86 degrees F). Do not freeze. Protect from light and moisture. Keep container tightly closed. Throw away any unused medicine after the expiration date.
Last Updated: April 7, 2009