Thyroid medication use as an assisted bodybuilder should be approached with caution and based strictly on individual neednot just because it's what you do during prep. Too often, both competitors and non competitors Carnitine, Acylcarnitines and Beta Oxidation l carnitine interactions: What not to mix with L carnitine? Crucial guide Tonum There are 3 main types of thyroid medications available T4 T3 (usually combined with T4) NDT desiccated thyroid (a combination of T4 + T3) Most are widely available