What is the difference and how are they used? This is a question that comes up quite a bit amongst breakout prone clients. Both are used in the treatment of acne but knowing how each works can help you with self treatment.
In the simplest terms, BP is an anti-bacterial. The p.acnes bacteria that causes acne are anaerobic, meaning they can't survive in the presence of oxygen. Benzoyl peroxide is an organic compound that breaks down into benzoic acid and oxygen upon contact with the skin. The benzoyl part of the molecule pulls the oxygen into the skin, flooding the bacteria with oxygen.
Cool fact - although BP is anti-bacterial, bacteria does not become resistant.
Bottom line, releasing oxygen into the pores is BP's function and the only reason it's effective. If you are experiencing cystic acne, pustules or obvious indications of infection, benzoyl peroxide can be very beneficial. The down side of BP is that most formulas consist of fairly large crystals so, in order to get the benefit within the follicles, the surface of the skin is overdosing, so to speak. This means that it can cause a lot of dryness, irritation and redness. Look for products with liquified BP such as Obagi or PCA. Benzoyl peroxide is sold in percentages from 2.5% to 10% but some studies have shown 2.5% to be as effective with less irritation. Try starting with a lowest percentage until you find what works best for you. Don't forget, benzoyl peroxide is also used as a bleaching agent so be careful that your favorite sweater doesn't come into contact with your product.
A beta-hydroxy acid, SA is a keratolytic and works to exfoliate the skin. For many people with acne, the cells in the lining of the follicles multiply quickly and stick together, clogging pores. SA dissolves the cement holding these sticky cells together, effectively clearing the pores and preventing subsequent infection. SA is also a powerful anti-inflammatory. This means that while SA is effective at fighting acne, it also has a soothing and calming effect on the skin. SA alone is best used for skin with open comedones (blackheads) or closed comedones ( white heads) found in grade I or grade II acne. For those with occasional hormonal breakouts, a 2% salicylic acid spot treatment like PCA's Acne Gel can often stop a breakout in its tracks. Note: because of the relationship to aspirin, please check with your doctor before using topical SA if you are pregnant or nursing.
Benzoyl peroxide and salicylic acid are effective when used individually and together to treat breakouts. There are a variety of causes and many types of acne but appropriate home care and professional treatments are available to give you clearer, more radiant skin. A licensed skin care professional can help you find the right treatment and products for you.