Having an overactive or underactive thyroid has been shown to affect levels of CoQ10 in the body. However, there doesn't appear to be research on whether CoQ10 supplementation affects thyroid hormone levels or thyroid medication. This is discussed in the "Cautions and Concerns"
section of the CoQ10 and Ubiquinol Supplements Review
, along with information about other potential drug interactions with CoQ10.
Be aware that other supplements, such as calcium, magnesium, iron and soy can interfere with thyroid medication, and biotin supplements can interfere with thyroid tests. More details about this can be found in our CL Answer about supplement interactions with levothyroxine
Also see the Thyroid Hormone
article in the Drug Interactions
section of the Encyclopedia.