Quick answer
For 48 hours after teeth whitening, enamel is temporarily more porous and stains easily: stick to the 'white shirt' diet (nothing you'd fear spilling on a white shirt), so skip coffee, black tea, red wine, dark sauces, turmeric and berries, or use a straw where practical. Manage the common temporary sensitivity with desensitising toothpaste and lukewarm drinks. Long-term, the shade holds one to three years: rinse after staining drinks, keep up routine cleans, and use take-home tray top-ups once or twice a year.
The 48-hour white-shirt diet
The rule of thumb: if it would ruin a white shirt, it will happily colour porous enamel. For two days, avoid or minimise coffee, black tea, red wine, cola, soy sauce and dark curries, beetroot, berries and turmeric. Milk, water, chicken, rice, pasta with pale sauces, eggs and bananas are all safe. A straw moves the worst offenders past the front teeth if abstinence fails.
Sensitivity: normal, temporary, manageable
A day or two of temperature zing is the most common after-effect. Use desensitising toothpaste (ideally started before treatment and continued after), keep drinks lukewarm, and skip acidic foods briefly. Sensitivity should fade within days; sharp pain in one specific tooth isn't a whitening effect and deserves a look; see sensitive teeth.
Keeping the shade for years
- Rinse or sip water after coffee, tea and wine; it's the accumulated bath that re-stains, not single exposures
- Keep routine professional cleans; surface stain removal alone visibly refreshes the shade
- If you whitened with custom trays, a top-up once or twice a year holds the result indefinitely; the trays are the asset, keep them safe
- Smoking re-stains faster than anything on the list, and yellowing is the least of its dental effects