In general, you should avoid eating or drinking anything that would stain a white shirt for 24-48 hours after a professional teeth whitening procedure is performed for you by your dentist.
Examples of things to avoid include but are not limited to:
1. Smoking
2. Dark Coffees and Teas
3. Dark Sauces
4. Red Wine
5. Beetroot
6. Curries
Do note that it is best that you get your teeth whitened by a licensed dentist in a registered dental clinic, rather than by a beautician, beauty therapist or beauty technician done in a spa or beauty parlour.