I've been on Mekinist/Tafinlar for 17 months and it worked great to put down my brain mets in 4 wks on 1x Mekinist/day & 4x 150 mg Tafinlar/day. It did come with those awful chills, often with incapacitating shakes and fever as high as 103 F. I reduced Tafinlar dosage by 25% after 8 months and chills/fever severity reduced but still hit every couple weeks for a couple days at a time. I reduced Tafinlar by 50% after that which again reduced chills/fever but still severe. Through my own experiments, I found that two things really helped:
1) As soon as you feel chills coming on, take 2 Tylenol and 2 Benadryl. If taken within 30 minutes of first feeling the chills it will reduce severity and length.
2) Stay hydrated. As long as I drank a lot of water the chills and fever were greatly reduced. I drank electrolyte water but regular water would probably work as well.
I hope this works for you. As Kate said, never lose hope.
CD–Santa Rosa CA
