What is diphenhydramine?
Diphenhydramine is an antihistamine. Diphenhydramine blocks the effects of the naturally occurring chemical histamine in the body.
Diphenhydramine is used to treat sneezing; runny nose; itching, watery eyes; hives; rashes; itching; and other symptoms of allergies and the common cold.
Diphenhydramine is also used to suppress coughs, to treat motion sickness, to induce sleep, and to treat mild forms of Parkinson's disease.
Diphenhydramine may also be used for purposes other than those listed in this medication guide.
What is the most important information I should know about diphenhydramine?
Use caution when driving, operating machinery, or performing other hazardous activities. Diphenhydramine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.
Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while taking diphenhydramine.
What should I discuss with my healthcare provider before taking diphenhydramine?
Do not take diphenhydramine if you have taken a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate) in the last 14 days. A very dangerous drug interaction could occur, leading to serious side effects.
Before taking this medication, tell your doctor if you have
glaucoma or increased pressure in the eye;
a stomach ulcer;
an enlarged prostate, bladder problems or difficulty urinating;
an overactive thyroid (hyperthyroidism);
hypertension or any type of heart problems; or
asthma.
You may not be able to take diphenhydramine, or you may require a lower dose or special monitoring during treatment if you have any of the conditions listed above.
Diphenhydramine is in the FDA pregnancy category B. This means that it is not expected to be harmful to an unborn baby. Do not take diphenhydramine without first talking to your doctor if you are pregnant.
Infants are especially sensitive to the effects of antihistamines, and side effects could occur in a breast-feeding baby. Do not take diphenhydramine without first talking to your doctor if you are nursing a baby.
If you are over 60 years of age, you may be more likely to experience side effects from diphenhydramine. You may require a lower dose of this medication.