Benzoyl Peroxide

• Benzoyl peroxide is the most common acne-fighting ingredient available in over-the-counter products. This ingredient works by soaking up excess oil and removing dead skin cells. This helps prevent clogged pores, which lead to acne. It's generally employed for the treatment of mild acne, though it can be very drying to the skin. An oil-free moisturizer should be used following application to reduce this side effect. Benzoyl peroxide can also bleach hair and clothing, so care should be used.
  
  

Salicylic Acid

• Salicylic acid is another common ingredient used in over-the-counter acne treatments. It helps the skin slough off dead skin cells faster, allowing the pores to unclog and acne to heal. It also prevents new lesions from forming. It must be used even after all acne has healed. Otherwise, acne will return. Though milder than benzoyl peroxide, it can still be drying to the skin, making an oil-free moisturizer a must.
  
  

Sulfur

• Sulfur is another common ingredient to treat acne and has been used in this way for many years. It seems to soak up excess oil and helps clear clogged pores, though it's not entirely clear why it works on acne. This ingredient is often combined with other effective acne fighters like salicylic acid and alcohol. Very rarely will you find sulfur on its own because of its foul odor.
  
  

Alcohol

• In some cases, alcohol is used to treat acne. Often included in over-the-counter preparations, alcohol is an astringent and removes oil from the skin. It is also an antimicrobrial. That being said, alcohol is very drying on the skin and could either irritate the skin or cause increased oil production. If you have sensitive skin, alcohol is not a recommended course of treatment.
  
  

Isotretinoin

• Isotreinoin is a form of Vitamin A often used in acne treatments to unclog pores and reduce inflammation. It primarily works to reduce the amount of oil and dead skin cells. It helps to unclog pores and reduce inflammation of current acne. Drying of the skin is a common side effect, so again, an oil-free moisturizer is a necessity.