What should I do if I experience tooth sensitivity or gum discomfort during or after use?

Temporary sensitivity to cold, air, or sweet foods is a known side effect of peroxide-based whitening and affects some users more than others. If it occurs, try these steps in order: (1) Reduce the session time by half for the next few applications. (2) Skip a day between sessions instead of using daily. (3) Brush with a desensitising toothpaste containing potassium nitrate or stannous fluoride for at least two weeks before starting and during the course. (4) Apply a small amount of desensitising toothpaste to the tray or directly on sensitive teeth for a few minutes before the whitening session. (5) Ensure the gel does not overflow onto gums — wipe excess away with a clean finger or cotton swab. If sensitivity becomes strong, sharp, or lasts more than 24–48 hours after a session, stop use and consult a dentist. Do not use if you have active gum disease, open cavities, cracked teeth, or exposed roots. The product is not suitable for anyone under 18, pregnant, or breastfeeding without professional advice. Avoid swallowing the gel; rinse well after each session.