Herpes virus: Cold sore is caused by herpes virus which is transmissible by contact (usually kissing). Once you've been infected you always have the virus which can be reactivated by stress, sunburn, trauma, fatigue, underlying illness, having procedures such as laser or chemical peels.
Answered 9/28/2016
5.6k views
6 doctors weighed in across 2 answers
A doctor has provided 1 answer
A doctor has provided 1 answer
7 doctors weighed in across 3 answers
4 doctors weighed in across 3 answers
90,000 U.S. doctors in 147 specialties are here to answer your questions or offer you advice, prescriptions, and more.
Ask your question