BHA, or beta-hydroxy acid, is a type of exfoliant commonly used in skincare products to help unclog pores and improve the appearance of dull, congested skin. The length of time it takes for BHA to start working can vary depending on factors such as skin type, the concentration of BHA in the product, and the frequency of use. However, on average, you may start to see a difference in your skin's texture and radiance within a few weeks of using a BHA-containing product, but it can take up to several months for the full benefits to become apparent. As with any skincare product, it's important to be consistent and patient to see the best results.