Levothyroxine is the standard treatment for hypothyroidism (underactive thyroid). It is a synthetic form of the thyroid hormone T4 (thyroxine) and is typically taken for life once prescribed.
How it works
Levothyroxine replaces deficient thyroid hormone, restoring normal metabolic function. The body converts T4 to the active T3 form as needed.
How to take it
Take on empty stomach, ideally 30-60 minutes before breakfast, with water only. Coffee, calcium, iron supplements, and antacids can reduce absorption.
Monitoring
TSH levels should be checked 6-8 weeks after starting or changing dose. Once stable, annual monitoring is usually sufficient. Target TSH is typically 0.4 to 4.0 mIU/L for most adults.