Levothoid is a medication used to treat thyroid diseases associated with deficiency of thyroid hormones. The medication contains Levothyroxine sodium which is synthetic analogue of natural hormone T4 (thyroxine).

Synthroid is a medication indicated for the treatment of thyroid problems. Synthroid contains levothyroxine sodium as an active ingredient which is identical to natural thyroid hormone levothyroxine. The medication comes in the form of tablets containing 25mcg, 50mcg, 100mcg and 200mcg of Levothyroxine.