Doctors treat mouth sores that are persistent with medications, steroid gel and medicated mouthwash, according to MedlinePlus. There are also preventative measures that a person can take to lower the chance of recurring sores in the mouth.
Medications for persistent mouth sores include lidocaine to numb the area and antiviral medicine if the sores are due to the herpes virus, explains MedlinePlus. A steroid gel may also work to treat mouth sores, and if swelling and inflammation occur, a paste, such as Aphthasol, may work. Doctors also may prescribe a special mouthwash, such as Peridex, which helps to treat the sores. Doctors also suggest preventative measures to avoid persistent mouth sores, such as avoiding hot foods and using a toothbrush with soft bristles.