If you have ulcers in your mouth after a fever, it is recommended to use medication for treatment. First, you need to take anti-viral drugs for treatment, do not exclude viral infection caused by ulcers, you can take the four seasons anti-viral combination, ribavirin granules or busulfan anti-inflammatory oral solution. Next, you can apply watermelon cream spray on the surface of the ulcer for anti-inflammatory treatment, which is often more effective for ulcers. You can use the intestinal paste on the ulcer wound, is also more effective. If the effect is not good, it is necessary to use the chemical containing drugs for treatment, you can mix 1 gentamicin, 1 dexamethasone, 1 vitamin B6, 1 vitamin C in 100ml of saline, used to gargle for the treatment of ulcers is very good, gargle for about three days, ulcers can be completely recovered. In addition, if there is still no effect, you need to go to the rheumatology department for examination to rule out the possibility of leukoaraiosis, which can cause mouth ulcers all over the mouth.