(بنزاك (بنزويل

Benzoyl peroxide has an antibacterial effect. It also has a mild drying effect, which allows excess oils and dirt to be easily washed away from the skin.
Use exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.
Wash your hands before and after applying this medication. Shake the lotion well just before each use. 
Clean and pat dry the skin to be treated. Apply benzoyl peroxide in a thin layer and rub in gently.
Do not cover the treated skin area unless your doctor has told you to. 
Benzoyl peroxide topical is usually applied one to three times daily. Follow your doctor's instructions.
Benzoyl peroxide may bleach hair or fabrics. Avoid allowing this medication to come into contact with your hair or clothing.
It may take several weeks before your symptoms improve. Keep using the medication as directed and tell your doctor if your symptoms do not improve.
If you miss a dose - use 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.
All medicines may cause side effects, but many people have no, or minor side effects.
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. Stop using benzoyl peroxide and call your doctor at once if you have severe stinging or burning of your skin. 
Less serious side effects may include:

• mild stinging or burning;
• itching or tingly feeling;
• skin dryness, peeling, or flaking; or
• redness or other irritation. 
  This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
  Store this medicine at room temperature in a tightly-closed container, away from heat and light.