As a skincare expert, I can provide some guidance on how long to leave salicylic acid on your face. Salicylic acid is a beta hydroxy acid (BHA) commonly used in skincare products for its exfoliating and acne-fighting properties. The duration for leaving salicylic acid on your face depends on several factors, including your skin type, sensitivity, and the specific product you are using.

For most people, it is generally recommended to start with a short contact time, especially if you are new to using salicylic acid. Begin by leaving the product on for about 5 to 10 minutes, then gradually increase the duration as your skin becomes accustomed to it. However, always follow the instructions provided by the product manufacturer.

If you have sensitive or dry skin, you may want to consider using salicylic acid as a spot treatment rather than applying it all over your face. This can help minimize potential irritation.

It is important to note that everyone's skin is unique, so it's essential to pay attention to how your skin reacts to salicylic acid. If you experience any redness, excessive dryness, or discomfort, reduce the contact time or discontinue use altogether. Additionally, it's crucial to incorporate a sunscreen into your skincare routine when using salicylic acid, as it can increase sun sensitivity.

If you have any concerns or specific skin conditions, I recommend consulting with a dermatologist who can provide personalized advice based on your needs.