I have had Lichen Planus for over 2 years on my gums with extreme bleeding. A few months ago I developed a sore on the side of my tongue. Hurt to eat talk..ect. My sister who is an RN suggested I take Valtrex. After taking 2 tablets a day for 4 days all Lichen Planus vanished. This leads me to believe it is viral. 2 months later and very little symptoms of LP.