I take levothyroxine (Synthroid), a thyroid hormone to treat hypothyroidism. Are there supplements or foods I should avoid, or be taking, due to this drug?

Answer:

Levothyroxine (Synthroid, Levoxyl), liothyronine (Cytomel), and other thyroid hormone drugs for hypothyroidism (underactive thyroid), can be affected by taking supplements and can affect your ability to absorb certain vitamins and minerals. Care must be taken with regard to using these supplements, for the reasons noted below.

Be aware that absorption of thyroid hormone drugs can also be affected by malabsorptive conditions like bariatric surgery, lactose intolerance, celiac disease, and inflammatory bowel disease. Treating hypothyroidism in people with these conditions may require a higher dose of thyroid hormone, but using liquid formulations or following a gluten-free diet (for celiac disease) may improve absorption and reduce the need for higher doses (Asamoah, Clin Case Rep 2021; Fallahi, Front Endocrinol (Lausanne) 2021).

Sign in as a member to learn which supplements or foods might affect the absorption of thyroid hormone drugs and which might affect thyroid function or thyroid hormone levels. Also find out which supplements are affected by thyroid hormone drugs and which can affect thyroid hormone tests. Supplements and foods discussed include alpha-lipoic acid, arginine, ashwagandha, beef organ supplements, biotin, calcium, cannabidiol, L-carnitine, chromium picolinate, coffee, cottonseed meal, cow's milk, cruciferous vegetables, elderberry, fiber, fluoride, grapefruit juice, green tea, iodine, iron, kelp, lithium, magnesium, milk thistle, resveratrol, soy, thyroid-boosting supplements, vitamins C and D, and walnuts.

Also, learn when to take levothyroxine and find out about issues regarding generic versions of this medication.