Knowing the Real Cause of Lip Blisters Is Essential for Finding the Right Treatment

Dannie got a fever blister every time she got a sunburn. Every weekend she spent on the beach was followed by a Monday she needed to find a way to cover a nasty blister. Then she eventually realized that her fever blisters could have a major effect on her sex life, too.

The most common cause of recurrent lip blisters is the milder form of the herpes virus, herpes simplex virus 1, also known as HSV-1. Most of us are exposed to the virus in early childhood, from the saliva of other infected children.

A few days after very first time a child is exposed to HSV-1, he or she may develop a high fever, crankiness, aches and pains parents can't understand, and blisters on the lips and inside the mouth. The child's immune system attacks the virus by destroying tissue with blistering and fever.

HSV-1 retreats into the trigeminal nerve underlying the cheeks, where it can't be attacked. It may stay there for years until it is awakened by a blow to the face, or hormonal changes, or the immune system's overactivity in response to a different infection. Then it can cause blisters over and over again, once or twice up to six times a year, always in the same place.

There are lots of potential triggers that activate the virus. The most important is overexposure to sunlight, but other triggers include:

  • Exposure to extreme cold
  • Biting your lip
  • Burning your lip on a hot drink
  • Getting punched in the mouth
  • A viral infection with a different virus elsewhere in the body
  • Wind
  • Allergies and
  • Getting run down with general fatigue after hard work, hard exercise, or stress.

If you get a tingly sensation in your lips that is always followed by a blister, then you probably have HSV-1. But not every blister on a lip is herpes.

Here are some other possibilities:

  • You can get "genital herpes," HSV-2, in the mouth, although this is less common than getting HSV-2 below the waist. A blood test can tell whether you have either "oral" HSV-1 or "genital" herpes simplex virus 2 (HSV-2), and a sample of a live blister can tested to see which kind of herpes you have.
  • If you have fever, tingling, itching, and muscle aches and pains before you break out, but then you break out with a blister than doesn't hurt, you could have a condition known as erythema multiforme. This condition can be caused by either HSV-1 or HSV-2, but it can also be a sign you have been exposed to one of the hepatitis viruses, the Epstein-Barr virus, measles, mumps, cat scratch fever, Salmonella, tuberculosis, or even polio. But if the blisters never itch or burn and never come back, that's a good sign your body has fought off the infection. Your doctor can tell you for sure.
  • If you have a whitish outbreak that itches and stings but doesn't turn red, then you could have a yeast infection of the mouth and throat.
  • Blistering can also be a reaction to a new medication, especially an antibiotic.

Blisters that keep coming back in the same place over and over again, however, are usually of herpes origin. The same treatments that work for cold sores will work for them.

Source:

Mell HK. Management of oral and genital herpes in the emergency department. Emerg Med Clin North Am. May 2008;26(2):457-73.

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