Do not use on irritated or damaged skin. Avoid direct sun exposure and use sunscreen, both during and a week after using REVOX B77 JUST Glycolic Acid 20%. Individual intolerance to the product is possible. If discomfort occurs, discontinue using the product. Before the first application, it is recommended to perform a sensitivity test: apply 1-2 drops of the product to a small area in the crook of the elbow, wait for 15 minutes, and rinse thoroughly with water. If no irritation is developed after 24 hours, the product is safe to use. Do not apply to inflamed, sunburned, or irritated skin. If you feel a pricking or burning sensation, the product must be washed off immediately with plenty of water. If the burning sensation continues, seek medical advice.