Surprising Interactions with Levothyroxine (Synthroid) and Herbal Supplements levothyroxine & orlistat? Orlistat can reduce the absorption of levothyroxine. This happens because orlistat blocks fat absorption, and levothyroxine may get trapped and eliminated with undigested Drugs and Other Substances Interfering with Thyroid Function Springer Nature Link Successive thyroid storms treated with L carnitine and low doses of Methimazole The American Journal of Medicine Adding L Carnitine and Selenium to Methimazole in Graves' Disease: A Prospective Randomized Trial on Thyroid Markers and Quality of Life Altered carnitine acylcarnitine profiles in levothyroxine treated congenital hypothyroid patients with fatigue: An LC MS MS based study from Bangladesh PLOS One