Watermelon is a sweet fruit, and if you can tolerate sweets, you can eat it, but you should not eat too much or eat cold watermelon, so as not to stimulate the pulp of the teeth to aggravate the pain. Toothache may be pulpitis or periapical inflammation, if the teeth can tolerate sweets, you can eat some watermelon in moderation, but should not eat or drink too much cold watermelon, so as not to cold stimulation caused by severe tooth pain, if the toothache can not tolerate sweets, it is not recommended to eat watermelon, you can eat some light and warm and cool food, such as congee, cabbage soup and so on. It is recommended to go to the hospital as soon as possible to check the cause of pain, if for endodontitis or periapical periodontitis need to carry out root canal treatment, if for wisdom teeth periapical periodontitis need to be rinsed to consider extraction.