How Long Is a Fever Blister Contagious?

Monica Patrick
Fever blister image

Fever blisters can spread from one infected person to another with little contact. Fever blisters are their most contagious when the blisters are plainly visible. Sores may be visible for one to two weeks at a time. If a fever blister is visible, it is contagious, so it is wise to avoid making skin-to-skin contact with people who have visible cold sores.

How Long Is the Contagious Period?

A common myth about fever blisters is that once they scab they are no longer contagious, but this is not the case. A healing fever blister may scab and shed a scab several times before actually reaching complete healing. During the scabbing period, fever sores are still contagious. Since most fever blisters last about 10 days, that is considered the contagious period. To be sure, the sore should be fully healed before it is not considered contagious any longer. Therefore, once the sore is no longer visible, it is safe to assume the contagious period is over. You cannot catch a fever blister from someone who doesn't have the actual sore on their skin.

Preventing the Spread of Blisters

To prevent the spread of the blisters, you should use these precautions.

  • Avoid kissing others while your fever blister is visible.
  • Clean the blisters daily to prevent bacterial infections. Use a cotton swab to clean your blisters - never your fingers - as this can spread the virus to others through your hands.
  • Wash your hands often especially after accidentally touching the fever blister.
  • Avoid picking at or scratching off the scab of your fever blister. Each time it re-opens you extend the contagious period.
  • Never drink from the glass of someone who has fever blisters. If you are infected, prevent anyone from drinking after you.
  • Do not share lipstick, lip gloss or lip balm with someone who has fever blisters - even if they have healed. Infected people should toss out their lip products and purchase new ones to prevent recurrence.
  • Do not engage in oral sex during an outbreak.

The Final Answer?

How long Is a fever blister contagious? From the initial tingling to the actual healing process is completed, and the sore is no longer visible, you should consider the blisters contagious.

How Long Is a Fever Blister Contagious?