The frequency of using glycolic acid depends on the product's concentration and your skin's sensitivity. It's generally recommended to start with a lower concentration and gradually increase usage, but daily use may be suitable for some people with lower concentrations (e.g., 5-10%) as part of their skincare routine. However, higher concentrations should be used less frequently to avoid skin irritation. Always follow the instructions on the product and consider consulting a dermatologist for personalized advice.