Phenindamine is an antihistamine. Phenindamine blocks the effects of the naturally occurring chemical histamine in your body.

Phenindamine is used to treat sneezing; runny nose; itching, watery eyes; hives; rashes; itching; and other symptoms of allergies and the common cold.

Phenindamine may also be used for purposes other than those listed in this medication guide.

Use caution when driving, operating machinery, or performing other hazardous activities. Phenindamine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while you are taking phenindamine.

Do not take phenindamine 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 phenindamine, or you may require a lower dose or special monitoring during treatment if you have any of the conditions listed above.

It is not known whether phenindamine will harm an unborn baby. Do not take phenindamine without first talking to your doctor if you are pregnant.

Infants are especially sensitive to the effects of antihistamines, and serious side effects could occur in a nursing baby. Phenindamine is not recommended if you are breast-feeding a baby. Do not take phenindamine 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 phenindamine. You may require a lower dose of this medication.