Lip Blisters: Herpes vs. Fungal Infections - Causes & Treatment

Herpes simplex virus type 1 (HSV-1) is the most common cause of lip blisters, also known as herpes labialis or cold sores. HSV-1 is a contagious virus that can be spread through direct contact with an infected person, such as through kissing or sharing drinks. Once infected with HSV-1, the virus can remain dormant in the body and periodically reactivate, causing outbreaks of lip blisters.

Fungal infections can also cause lip blisters, but they are less common than herpes blisters. Candida albicans, a type of yeast that normally lives on the skin and in the mouth, can sometimes cause oral thrush, which can include blisters on the lips. Fungal lip blisters are more common in people with weakened immune systems.