Diphenhydramine is an antihistamine that reduces the natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Phenylephrine is a decongestant that shrinks blood vessels in the nasal passages. Dilated blood vessels can cause nasal congestion (stuffy nose).

The combination of diphenhydramine and phenylephrine is used to treat runny or stuffy nose, sneezing, watery eyes, and sinus congestion caused by allergies, the common cold, or the flu.

Diphenhydramine and phenylephrine may also be used for other purposes not listed in this medication guide.

Do not give this medication to a child younger than 2 years old. Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children.

Do not use any other over-the-counter cough, cold, allergy, or sleep medication without first asking your doctor or pharmacist. If you take certain products together you may accidentally take too much of one or more types of medicine. Read the label of any other medicine you are using to see if it contains an antihistamine, decongestant, or cough suppressant.

Avoid drinking alcohol while you are taking this medication. It can add to drowsiness caused by an antihistamine.

Avoid taking diet pills, caffeine pills, or other stimulants (such as ADHD medications) without your doctor's advice. Taking a stimulant together with a decongestant can increase your risk of unpleasant side effects.

This medication can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.

Tell your doctor if you regularly use other medicines that make you sleepy (such as other cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by diphenhydramine.

You should not use this medication if you are allergic to diphenhydramine or phenylephrine.

Before taking this medication, tell your doctor if you are allergic to any drugs, or if you have:

• asthma;

• heart disease or high blood pressure;

• diabetes;

• a thyroid disorder;

• glaucoma;

• kidney disease;

• an enlarged prostate; or

• problems with urination.

If you have any of these conditions, you may need a dose adjustment or special tests to safely take this medication.

This medication may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

This medication may pass into breast milk and could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

Older adults may be more likely to have side effects from this medication.

Artificially-sweetened liquid forms of cold medicine may contain phenylalanine. This would be important to know if you have phenylketonuria (PKU). Check the ingredients and warnings on the medication label if you are concerned about phenylalanine.