[Question #9429] When is a cold sore no longer contagious

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32 months ago
I'm generally aware you can pass HSV1 without a sore, and the majority of people already have HSV1.
By best estimates, when is a cold sore no longer contagious? I have heard conflicting information, most notably because my doctor once told me that once it scabs over, it's no longer contagious, with the reasoning being that it's effectively "healed" at that point -- that the infection is no longer active. 
However it seems that the general consensus online (blogs, articles etc.) is that you should treat the cold sore as infectious until it is 100% gone, and you have a fresh path of skin under the spot. Reasonable of course, to be extra confident it's no longer contagious.
It's obviously very isolating and depressing to wait day after day for a cold sore to dissipate, but also obviously don't want to rush it. So when exactly should I feel confident that the cold sore is no longer contagious? Also, separately, in theory I had a contagious cold sore and kissed a girl, and she went down on me, is it possible for her to transfer the HSV1 virus to me downstairs?
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Terri Warren, RN, Nurse Practitioner
32 months ago
I think you should consider cold sores contagious until there is no evidence of one BUT we know that people can shed virus from the mouth even when there is no evidence of a cold sore present at all.    its difficult to hear but it is definitely true.  So trying to sort out when you might be infectious after a cold sore heals is a bit of an exercise in futility.  

If you have a cold sore and someone kisses you and then gives you oral sex, it is extremely unlikely that you would get it genitally after you have a well established oral HSV 1 infection.

Terri
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32 months ago
Okay. Related follow up question -- is there a chance of spreading it from upstairs to downstairs on myself, doing something like touching it, then touching downstairs, or using a towel and it spreading? Sounds like what you're saying is since it's "established" upstairs, it's unlikely for it to appear downstairs period?
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Terri Warren, RN, Nurse Practitioner
32 months ago
Once an infection has been well established (about 4 months) in one location, it is extremely unlikely you would acquire it in a new location (including dong it yourself)

Terri
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