When it comes to using BHA (beta hydroxy acid) on your face, the answer depends on a few factors. The type of skin you have, as well as the strength of the BHA product you're using are important considerations. Generally speaking, if you have oily or acne-prone skin and are using a milder concentration of BHA (1% or less), then you should use it once or twice per week. For normal to combination skin types, start with once every two weeks and adjust accordingly depending upon how your skin responds. If you have dry or sensitive skin and/or are using stronger concentrations of BHA (2% -10%), only use it once every two weeks—and even less frequently than that if irritation occurs. When applying any topical acid product such as BHA, be sure to apply sunscreen during the day since acids can increase sun sensitivity in some people. Using proper technique is also key for optimal results: Apply a thin layer directly onto clean dry skin at night after cleansing; allow enough time for the product to absorb before layering other products over top; follow up with moisturizer afterwards.