It seems harmless enough to borrow your girlfriend's lip balm or dry your face on your buddy's towel, but these simple acts can spread the virus that causes cold sores (also called fever blisters). It starts as a burning and tingling around your lips (prodromol symptoms), the skin hardens, and sure enough two days later the tell-tale red blisters appear. The lesions turn yellow and crusty, break and ooze, and then slough off all within seven to 10 days, and without leaving a scar. Symptoms can also be accompanied by fever, sore throat, sore mouth, and drooling in young children.

Most commonly found around the mouth, cold sores can also appear on your chin, nostrils, and fingers, and can occur inside your mouth. Often caused by herpes simplex virus (HSV) type 1, the type 2 strain which is usually linked to genital herpes can also cause cold sores.

There is no cure for cold sores, but prescription antiviral medications may shorten the duration, and topical treatments such as lidocaine or Zilactin (benzyl alcohol) can ease the worse symptoms. Abreva is an FDA-approved, non-prescription ointment, and it may reduce blister healing times.

If you don't want to go the prescription route for cold sore treatment, then lemon balm (Melissa officinalis) has been shown to ameliorate some cold sore symptoms. In a one study of 116 people, some patients applied lemon balm cream to cold sores caused by HSV. Their redness and swelling improved within two days, though pain and scabbing persisted. Lemon balm is a member of the mint family, and is reputed to have antiviral and antibacterial properties.

Don't confuse cold sores with canker sores, which are ulcers that occur on the soft tissue of the mouth. Canker sores are not contagious but cold sores are highly contagious. If you do have a cold sore, avoid kissing and skin contact with infants or anyone with a compromised immune system, and be mindful of touching other areas of your own body. Don't touch your eye area in particular, as a herpes simplex infection of the eye can scar the cornea and is a leading cause of blindness.

The virus can spread even when dormant (called viral shedding), and with no apparent symptoms. Be careful, don't share utensils, and try to keep your hands away from the infected area. Frequent hand washing is always a good idea. Many of the usual suspects are also cold sore triggers: stress, lack of sleep, a cold or flu, and staying in the sun for extended periods without sun block.