Sulfacetamide sodium is an antibiotic that fights bacteria on the skin.

Mexar (for the skin) is used to treat acne, dandruff, seborrheic dermatitis (red, flaking skin rash), and certain skin infections.

Mexar may also be used for purposes not listed in this medication guide.

You should not use this medicine if you are allergic to sulfa drugs.

Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended.

You may need to shake the medicine before each use. Follow the directions on your medicine label.

Make sure the treatment area is clean and dry before using Mexar cream, gel, lotion, or solution. Apply the medicine in a thin layer and rub in gently.

To use sulfacetamide sodium soap, wet the skin and apply enough of the medicine to work into a lather. Massage the lather on the skin gently and then rinse thoroughly with plain water. Pat the skin dry with a clean towel.

Apply the foam to dry hair when treating your scalp. Massage gently into the scalp until all the foam dissolves. Allow the foam to dry completely on the treated area.

Do not apply Mexar over large skin areas.

Wash your hands after applying this medicine.

If you are using this medicine on your scalp, wash your hair with a non-medicated shampoo at least once per week during treatment.

Mexar is usually applied 2 times per day for 8 to 10 days. Space your doses evenly by applying the medicine at the same times each day.

You may need to keep using the medicine once or twice per week, or once every other week. Follow your doctor's instructions. Call your doctor if your condition comes back after you stop using Mexar.

Call your doctor if your symptoms do not improve, or if they get worse while using this medicine.

Store at room temperature away from moisture and heat. Do not freeze.

Store the foam canister upright and keep away from open flame or high heat, such as in a car on a hot day. The canister may explode if it gets too hot. Do not puncture or burn an empty canister.

You should not use Mexar if you are allergic to sulfacetamide sodium or sulfa drugs.

To make sure this medicine is safe for you, tell your doctor if you have:

• lupus;

• asthma; or

• a sulfite allergy.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether sulfacetamide sodium topical passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Do not use this medicine on a child younger than 12 years old.

Apply the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea and vomiting, blood in your urine, or urinating less than usual.

Do not use Mexar for any skin infection that has not been checked by a doctor.

Avoid getting this medicine in your eyes, nose, or mouth. If this does happen, rinse with water. Do not use the medicine on sunburned, windburned, dry, chapped, irritated, or broken skin. Avoid getting Mexar soap on your eyelids or lips while washing with it.

Avoid getting this medicine on your clothing. Mexar may leave a slight yellow color on light fabrics.

Avoid exposure to sunlight or tanning beds. Mexar can make you sunburn more easily. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

Avoid using other medications on the areas you treat with Mexar unless your doctor tells you to.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Mexar may cause serious side effects. Stop using Mexar and call your doctor at once if you have:

• the first sign of any skin rash, no matter how mild;

• pale skin, easy bruising or bleeding;

• new or worsening skin infection;

• liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

• lupus-like syndrome--joint pain or swelling with fever, swollen glands, muscle aches, chest pain, vomiting, unusual thoughts or behavior, and patchy skin color; or

• severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects of Mexar may include:

• mild swelling, itching, or redness of treated skin;

• dry skin; or

• yellow discoloration of treated skin (may be a sign that you have applied too much of the medicine).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.