You can use a toner before applying sunscreen. In fact, using a toner as part of your skincare routine before applying sunscreen can be beneficial. A well-hydrated and balanced skin surface can enhance the effectiveness of your sunscreen by allowing it to adhere evenly and provide better protection. Just ensure that the toner you're using is lightweight, easily absorbed, and doesn't leave a heavy residue on the skin. This will help the sunscreen to sit well on your skin without interference.