Hi, Welcome to H C M It seems that you are having herpes simplex labialis.Also known as cold sore. It is caused by herpes simplex virus type 1. Herpes simplex type 1, which is transmitted through oral secretions or sores on the skin, can be spread through kissing or sharing objects such as toothbrushes or eating utensils Often, the appearance of herpes simplex virus is typical and no testing is needed to confirm the diagnosis. If a health care provider is uncertain, herpes simplex can be diagnosed with lab tests, including DNA -- or PCR -- tests and virus cultures. There is no treatment that can cure herpes. Antiviral medications can, however, prevent or shorten outbreaks during the period of time the person takes the medication. Severe infection may require treatment with an antiviral agent. Typical doses of oral antiviral drugs for cold sores are: aciclovir – 200mg five times daily for 5 days valaciclovir – 1 g three times daily for 7 days famciclovir – as a single dose of 3 x 500mg. Repeated courses may be prescribed or the medication may be taken continuously to prevent frequent attacks. Topical aciclovir or penciclovir, in the form of a cream applied to affected areas, shortens attacks of recurrent herpes simplex provided it is started early enough. Recurrences of herpes simplex are triggered by following factors.. -Minor trauma to the affected area -Other infections including minor upper respiratory tract infections -Ultraviolet radiation -Emotional stress -Operations or procedures performed on the face -Dental surgery You should try to avoid above factors to prevent relapse.. I hope you got my answer. However you consult dermatologist. Regards. Dr.Ilyas Patel MD