# Levothyroxine --- **Levothyroxine** (brand name: **Synthroid**) is a [[hormone|hormonal]] drug that is used to treat [[thyroid|hypothyroidism]]. It works by replacing or acting as [[thyroid hormone]] which can increase one's [[basal metabolic rate]]. It can also be used to treat euthyroid goiters. It is a *lifelong therapy*, you need to constantly take it forever now. Levothyroxine can be taken PO or IV Dose is based on serum TSH levels Administer same time each day in morning (prevent insomnia) Administer with full glass of water, on empty stomach 30-60 minutes prior to breakfast Usually started low and then increased as needed (especially in older adults) When starting, it's important to monitor for tachycardia and chest pain. ___