Levothyroxine: Side Effects, Uses & Monitoring
Levothyroxine sodium is used for the following indications: Hypothyroidism - As replacement or supplemental therapy in congenital or acquired hypothyroidism of any etiology, except transient hypothyroidism during the rec
- Data source
- FDA labeling via NIH DailyMed (label 05ab038e…)
- Label version
- current
- Last reviewed
- 2026
Reported adverse reactions
Reactions listed in current FDA labeling, with the highest frequency reported across summarized placebo-controlled trials.
No structured frequency data available in current labeling. Consult the official label.
Labeled uses (from FDA prescribing information)
Levothyroxine sodium is used for the following indications: Hypothyroidism - As replacement or supplemental therapy in congenital or acquired hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis. Specific indications include: primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) hypothyroidism and subclinical hypothyroidism. Primary hypothyroidism may result from functional deficiency, primary atrophy, partial or total congenital absence of the thyroid gland, or from the effects of surgery, radiation, or drugs, with or without the presence of goiter. Pituitary TSH Suppression - In the treatment or prevention of various types of euthyroid goiters (see WARNINGS and PRECAUTIONS ), including thyroid nodules (see WARNINGS and PRECAUTIONS ), subacute or chronic Iymphocytic thyroiditis (Hashimoto's thyroiditis), multinodular goiter (see WARNINGS and PRECAUTIONS ), and, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.
Tests providers may use to monitor Levothyroxine therapy
Conditions associated with Levothyroxine in labeling
Hypothyroidism
A condition in which the thyroid gland does not produce enough thyroid hormone, slowing metabolism and affecti...
Thyroid Cancer
Cancer of the thyroid gland, which often presents as a painless neck lump or nodule....
Thyroid Nodules
Lumps that form in the thyroid gland. Most are benign, but some require evaluation to rule out cancer....
Frequently Asked Questions
What is Levothyroxine used for?
FDA labeling lists the approved uses shown above under "Labeled uses." This summary is informational; only a qualified prescriber can determine whether a medication is appropriate for you.
What are the most commonly reported side effects of Levothyroxine?
Current labeling for this ingredient does not include a structured frequency table that we can reproduce. Review the official label linked below.
Does Levothyroxine require lab monitoring?
Labeling and standard practice associate Levothyroxine with periodic laboratory monitoring; the tests above are commonly ordered by clinicians to monitor patients on therapy. Your provider decides what is appropriate.
Where does this information come from?
All clinical facts on this page were extracted from the current FDA-registered product labeling for this ingredient, published by manufacturers through NIH DailyMed. See the source link below.
Medical disclaimer: Educational content extracted from public FDA labeling. Not medical advice. Always consult a qualified healthcare professional before starting, stopping, or changing any medication.