- 1). Buff your nails gently with an emery board or professional nail buffer. Don't rub too hard, because this can thin and damage your nails; a light buffing can remove a bit of the discoloration.
- 2). Squeeze a lemon into a bowl of warm water. Soak your fingers in the bowl for about 10 minutes. Wash your hands in warm water, and repeat if necessary. This should get rid of most of the yellow stains.
- 3). Cut tooth-whitening strips into small pieces the size of your nails, and place them on your nails. Leave them on for about 10 minutes, then remove and wash your hands in warm water. This should eliminate any remaining stains.
- 4). Paint your nails with a nail-whitening polish such as Sally Hansen Insta-Brite. This will disguise any yellow stain that is left.
Source...