Antihistamines (Systemic)

Precautions While Using This Medicine

Before you have any skin tests for allergies, tell the doctor in charge that you are taking this medicine. The results of the test may be affected by this medicine.

When taking antihistamines on a regular basis, make sure your doctor knows if you are taking large amounts of aspirin at the same time (as for arthritis or rheumatism). Effects of too much aspirin, such as ringing in the ears, may be covered up by the antihistamine.

Antihistamines will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine .

This medicine may cause some people to become drowsy or less alert than they are normally. Even if taken at bedtime, it may cause some people to feel drowsy or less alert on arising. Some antihistamines are more likely to cause drowsiness than others. Drowsiness is less likely with cetirizine, and rare with desloratadine and loratadine. Make sure you know how you react to the antihistamine you are taking before you drive, use machines, or do anything else that could be dangerous if you are not alert .

Antihistamines may cause dryness of the mouth, nose, and throat. Some antihistamines are more likely to cause dryness of the mouth than others . For temporary relief of mouth dryness, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

For patients using dimenhydrinate, diphenhydramine, or hydroxyzine:

• This medicine controls nausea and vomiting. For this reason, it may cover up the signs of overdose caused by other medicines or the symptoms of appendicitis. This will make it difficult for your doctor to diagnose these conditions. Make sure your doctor knows that you are taking this medicine if you have other symptoms of appendicitis such as stomach or lower abdominal pain, cramping, or soreness. Also, if you think you may have taken an overdose of any medicine, tell your doctor that you are taking this medicine.

For patients using diphenhydramine or doxylamine as a sleeping aid:

• If you are already taking a sedative or tranquilizer, do not take this medicine without consulting your doctor first.