@eeileen and @fivec, I've been on Tagrisso for three and a half years now. Nail splitting was the second symptom I noticed. I take 10mg of Biotin daily and occasionally rub Vitamin E oil into the nails and cuticles. My Oncologist approves of the Biotin and assures me it doesn't interact with anything else I'm taking.

@eeileen, There is no numbness or tingling, though. I've never heard of that as a Tagrisso side effect. I recommend letting your doctor know.