Whitening gels are now one of the most popular ways to brighten a smile at home. Knowing what’s inside the syringe — and how each ingredient behaves — makes it much easier to choose a product that suits your teeth.
1. Active ingredients
Most gels rely on either hydrogen peroxide or carbamide peroxide. Hydrogen peroxide acts faster and works at concentrations from around 3% up to 40%, lifting stains by penetrating enamel and dentin.
Carbamide peroxide breaks down into hydrogen peroxide more slowly, which makes it gentler on sensitive teeth and a common choice for take-home kits.
Many modern formulas also include potassium nitrate or fluoride to calm sensitivity, plus calcium phosphate to support enamel remineralisation.
2. Formulation type
In-office gels are high strength and applied by a dental professional under controlled conditions.
At-home tray gels are lower strength and designed to be worn in a custom or boil-and-bite tray for a set time each day.
Pen and brush-on gels offer the most convenience for touch-ups — quick to apply, easy to travel with, but typically slower to produce visible change.
3. Safety and sensitivity
A well-formulated gel should clearly state its peroxide concentration, recommended wear time, and any desensitising agents.
Always follow the directions — overuse is the main cause of irritation and rebound sensitivity.
