Key takeaways
Synthroid (levothyroxine) and Thyrolar (liotrix) are both used to treat low thyroid hormone levels, but they have some key differences. Synthroid is a synthetic form of the T4 thyroid hormone and is taken once daily on an empty stomach. It is available in both pill and liquid forms. Thyrolar, on the other hand, was a combination of two thyroid hormones, T4 (levothyroxine) and T3 (liothyronine), but it has been discontinued since December 2018. While Synthroid is still widely available and commonly prescribed, Thyrolar is no longer on the market due to business reasons, not because of safety or efficacy concerns. If you need a combination of T4 and T3, you would need to take separate medications like Synthroid and Cytomel (liothyronine) or consider a naturally-derived option like Armour Thyroid. Synthroid requires careful timing around meals and other medications to ensure proper absorption, whereas Thyrolar's specific administration guidelines are no longer relevant due to its discontinuation.
