Can i be on fat burner tablets whilst on tarceva (erlotinib)?

I can't recommend it: Most fat-burner tablets are mixes of placeboes and medicines that work like caffeine. Tarceva (erlotinib) / Erlotinib is a hard-core chemotherapeutic agent for some of the most difficult common cancers. In your situation, if you're looking at actively trying to lose weight, you'll need also to make sure you support your skeletal muscle mass. You can do this only by hard aerobic exercise.