I woke up this morning with a coating on my tongue that was a blue-green color. I thought over what I had eaten yesterday, but nothing out of the ordinary and nothing in those color families. I am a 66 year old female who is currently undergoing radiation to the retinas. I completed six rounds of high-dose methotrexate this summer for Primary Intraocular Lymphoma (so rare almost no one in the world has had it). I have had no side-effects (except being quite tired) from any of my treatments, which has amazed everyone, including my doctors. I also did not lose my hair from the chemo. I hope this blue-green tongue doesn't indicate anything serious.