Levothyroxine
Synthroid (levothyroxine) is a synthetic thyroid hormone used to treat hypothyroidism and other thyroid disorders. It works by replacing the thyroid hormone that your body normally produces, helping to restore normal metabolic function. This medication is typically taken daily and requires regular monitoring to ensure proper dosing.
Synthroid is a thyroid hormone replacement medication used to treat underactive thyroid conditions.
Key facts at a glance
- RxNorm
- 224920
- Generic
- Synthroid
- Class
- brand-name
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Synthroid is primarily used to treat hypothyroidism (underactive thyroid), as well as certain types of thyroid cancer and goiter. It may also be used in thyroid-stimulating hormone (TSH) suppression therapy.
Synthroid contains levothyroxine sodium, a synthetic form of the thyroid hormone T4. It works by binding to thyroid hormone receptors in the body and supplementing or replacing the natural thyroid hormone to restore normal metabolic processes, energy levels, and growth.
Synthroid should be taken on an empty stomach, typically 30-60 minutes before breakfast. It may take several weeks to notice full effects, and dose adjustments should only be made under medical supervision. Regular blood tests are needed to monitor thyroid function. Certain medications and supplements can interfere with absorption.
Official drug label
WellAlly may earn a referral fee from linked resources at no extra cost to you. Editorial content is never influenced by commercial relationships.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 9, 2026. · Read our editorial policy