Fever blisters and canker sores
Canker sores and fever blisters
Are fever blisters and canker sores the same thing?
No. Canker sores occur only inside the mouth and are not contagious. They sometimes occur as a result of trauma (biting the inside of the lip, burning the mouth with hot food), but may also occur without any known reason.
Fever blisters or cold sores are caused by herpes simplex virus type 1 and are very contagious. Fever blisters often come back in the same location.
Gonsalves WC, Chi AC, Neville BW. Common oral lesions. Part I. Superficial mucosal lesions. Am Fam Physician. 2007;75(4):501-507.
Habif TP. Warts, herpes simplex, and other viral infections. In: Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2009: chap 12.
Reviewed By: Linda Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.