Herpes simplex virus type 1 (HSV-1), also known as herpes labialis, is the etiologic agent of vesicular lesions of the oral mucosa commonly referred to as "cold sores". HSV-1 can also cause clinical disease in a wide variety of other anatomic locations including the genitalia, liver, lung, eye, and central nervous system. These infections can be severe, particularly in the setting of immunosuppression, such as inflammatory arthropathy patients on Methotrexate ± biological therapies. Here, we highlight the importance of physician awareness of HSV due to its potential impact for rheumatology patients.