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Headaches while using fluorouracil

After a couple of months of continuous use of Tolak (fluorouracil), I began having headaches. This occurred after I began treating both forearms at the same time. I've read that the area of skin covered by fluorouracil should be no larger than about 75 square inches. The area of my forearms is about 100 square inches, so I assume that perhaps this is what caused the headaches. Anyone else experienced anything similar to this?


  1. It's pretty likely to be the Fluorouracil in my experience. The maximum area that I've seen mentioned is 22 x 22 cm which is about 9 x 9 in or 81 sq in. I've just completed both of my lower thighs - I don't have a big frame - and I had some nausea when I started them and was finishing off one arm. It passed once I stopped treating the arm. I think that was overdoing it, dose-wise.
    Maybe take a break after your arms are done and give your body a chance to expel the remaining drug. Having said that, when I took a break, I got the initial side-effects I'd had when I restarted - headaches, nausea, light flu-like symptoms - for the first few days. It's a pretty serious drug, the ol' 5-FU.

    1. ...I am sorry to hear you have dealt with headaches while using fluorouracil. Many users do report headaches as a side effect of using the cream. You are quite right about the size of the area being treated. Generally speaking, the smaller the area, the fewer side effects you may experience. In my own experience, it also depends on the frequency of application and the length of the treatment.


      I am including an article on some of the reported side effects of fluorouracil along with an article on the healing stage.


      https://skincancer.net/life-with-skin-cancer/efudex-side-effects
      https://skincancer.net/life-with-skin-cancer/efudex-side-effects-tips


      I hope your treatment yields some wonderful results when it is all said and done.


      All my best,
      April, SkinCancer.net, Moderator

      1. April, thanks for your comment.

        1. ...Just checking back in with you. How did your treatment go? I hope healing has been quick for you and you got some wonderful results! April, SkinCancer.net, Moderator

      2. I wound up just applying on smaller areas at a time and the headaches stopped! I appreciate your concern. Thanks.

        1. Oh, that's great to hear! Spot-treating is usually much easier. Sending you lots of positive thoughts for continued healing! April, SkinCancer.net, Moderator

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