Mild, temporary sensitivity is the most common side effect of whitening — and it's almost always avoidable. With a few small adjustments, most people whiten comfortably from start to finish.
Why sensitivity happens
Peroxide temporarily opens tiny channels in the enamel so the gel can lift stains. While those channels are open, cold or sweet foods can reach the nerve more easily. It's short-lived and reverses on its own — but you can keep it to a minimum.
Six ways to stay comfortable
- Use the right amount of gel. A thin line in each tray is enough. More gel doesn't whiten faster — it just spills onto the gums and causes irritation.
- Check your tray fit. A snug, well-trimmed custom tray keeps gel on the teeth and off the gums. A poor fit is the number-one cause of irritation.
- Start at 10%. The lower concentration is the gentlest place to begin. Step up only once you know how your teeth respond.
- Build in rest days. If teeth feel tender, skip a day. Whitening every other day still works — comfort matters more than speed.
- Lean on the formula. Both Opalescence PF and Pola Night include potassium nitrate and fluoride, which calm the nerve and re-strengthen enamel as you whiten.
- Use a sensitivity toothpaste. Brushing with a potassium-nitrate toothpaste for a week before and during treatment builds up real protection.
What to avoid
Don't overfill trays, don't wear gel longer than directed to "speed things up," and avoid very hot or very cold drinks right after a session while the enamel re-seals.
For adults 18 and over. If sensitivity is sharp, lasting, or focused on one tooth, stop and speak with a dentist — that can signal an issue unrelated to whitening.