Canker sore and Famvir

Hello.  I have recurrent cold sores and have a Famvir prescription for this.  Two weeks ago, I felt and saw redness, lumpiness and then a whitish sore that I associate with cold sores and hurriedly bolted down 1500mg of Famvir. But the sore/lesion seems to have been on the inside of my lip (the moist inner mouth), and not on my skin. Stupidly I didn't think of this til later.  I think, in my panic, I just went for the meds as the easy solution without thinking.  Upon reflection, I think it may have been a canker sore, not a cold sore, and my understanding is that cold sores aren't common inside the mouth.  In any case, it went away within 12 hours, and now it's like a clear dark dot, as if I had a pencil jab there.  It's been this way for most of the intervening two weeks, with no pain, itching, nothing.  I'm posting because I'm still wondering what it was. If it was a canker sore, why did it react to the Famvir?  Does Famvir still have an effect on canker sores then, as well as cold sores? Am I contagious? Was I ever contagious? And can I actually kiss my husband again?

Thanks for any advice!  Much appreciated.

[Bhupinder Kaur, MD]

Hello,
Canker sores are small shallow ulcers that appear in the mouth and often make eating and talking uncomfortable. They are generally caused by  Stress, tissue injury, eating certain foods and other causes. Pain from a canker sore generally lessens in a few days and the sores usually heal without treatment in a few days or 1-2 weeks. From the symptoms the possibility of cold sores cannot be ignored esp. after the treatment with Famvir. You need to get some investigations like sample from the sores to identify the virus, culture analysis, Tzanck smear, antigen and antibody studies and blood sampling for antibody studies done to confirm the diagnosis. My sincere advice would be to consult a dermatologist. These investigations are needed because the virus may be shed even if there are no active lesions.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.