You should not use Nasonex if you are allergic to mometasone.

Avoid getting Nasonex in your eyes. If this does happen, rinse with water and call your doctor.

Nasonex can lower the blood cells that help your body fight infections. Avoid being near people who are sick or have infections. Call your doctor for preventive treatment if you are exposed to chicken pox or measles. These conditions can be serious or even fatal in people who are using Nasonex.

Before using Nasonex, tell your doctor if you have been sick or had an infection of any kind. You may not be able to use Nasonex until you are well.

Also tell your doctor if you are allergic to any drugs, or if you have:

• glaucoma or cataracts;

• herpes simplex virus of your eyes;

• tuberculosis or any other infection or illness;

• sores or ulcers inside your nose; or

• if you have recently had injury of or surgery on your nose.

FDA pregnancy category C. This medication may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. It is not known whether Nasonex passes into breast milk or if it could harm a nursing baby. Do not use Nasonex without telling your doctor if you are breast-feeding a baby.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have any of these serious side effects:

• severe or ongoing nose bleed;

• sores in the nose that won't heal;

• wheezing, trouble breathing;

• vision problems; or

• fever, chills, body aches, flu symptoms.

Less serious side effects may include:

• headache;

• stuffy nose, sore throat, cough;

• muscle or joint pain;

• nausea; or

• sores or white patches inside or around your nose.