Don't just spot-treat pimples! Stop new breakouts before they even appear. Apply your topical acne medications like Retin A, benzoyl peroxide, and salicylic acid over the entire area affected by acne, not just on existing blemishes.
Most anti-acne products work by keeping pores clear of blockages or by reducing the amount of acne-causing bacteria. Since these treatments prevent new pimples from forming, they need to be applied over the entire face (or back) to work effectively.
This isn't to say that spot-treatment doesn't have a place in your skin care routine. Using an over-the-counter spot treatment periodically to treat existing blemishes is still okay (provided your doctor approves, of course). One that contains sulfur is preferable, to help heal active pimples more quickly. Keep in mind, however, that over-doing the spot treatment can cause excessive dryness, redness, and peeling, especially if used in conjunction with other acne medications.
So remember, use spot treatments only to target existing blemishes. To prevent new pimples from forming, make sure to cover all problem areas with your acne medication. You'll get better results and clearer skin.

