LEVOXYL (levothyroxine sodium)
Levoxyl is a synthetic L-thyroxine (T4) indicated for pediatric and adult patients as replacement therapy for primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism. It is also indicated as an adjunct to surgery and radioiodine therapy for the management of well-differentiated thyroid cancer to suppress pituitary thyrotropin (TSH). **Limitations of Use:** Levoxyl is not indicated for the suppression of benign thyroid nodules or nontoxic diffuse goiter in iodine-sufficient patients, nor is it indicated for treating hypothyroidism during the recovery phase of subacute thyroiditis.
How LEVOXYL Works
Levothyroxine (T4) exerts its physiological effects by controlling DNA transcription and protein synthesis. T4 and its active metabolite, T3, diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA, activating the synthesis of messenger RNA and cytoplasmic proteins. While Levoxyl provides T4, the majority of thyroid hormone activity is mediated by T3, approximately 80% of which is derived from the peripheral deiodination of T4.
Development Insights
Details
- Status
- Prescription
- First Approved
- 2001-05-25
- Routes
- ORAL
- Dosage Forms
- TABLET
LEVOXYL Approval History
What LEVOXYL Treats
2 indicationsLEVOXYL is approved for 2 conditions since its original approval in 2001. These indications span multiple therapeutic areas including oncology, immunology, and more.
- Hypothyroidism
- Thyroid Cancer
LEVOXYL Boxed Warning
NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS Thyroid hormones, including LEVOXYL, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their ano...
WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS Thyroid hormones, including LEVOXYL, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects [see Adverse Reactions (6) , Drug Interactions (7.7) , Overdosage (10) ] . WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS See full prescribing information for complete boxed warning. Thyroid hormones, including LEVOXYL, should not be used for the treatment of obesity or for weight loss. Doses beyond the range of daily hormonal requirements may produce serious or even life-threatening manifestations of toxicity ( 6 , 7.7 , 10 ).
LEVOXYL Competitive Set
ProThree rings of competition based on shared molecular targets and treated indications.
Direct competitors
Same target(s) AND same indication — head-to-head.
Indication competitors
Same indication, different mechanism — what else might this patient receive?
Filters applied: drops same-active-ingredient (505(b)(2) reformulations), route-mismatch (topical vs systemic), and cross-therapeutic-area matches in same-indication rings.
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Clinical Trial Registry
6 trials| Trial | Sponsor ID | Phase | Status | Title |
|---|---|---|---|---|
| NCT06073665 DOT4 | 1R01AG081698-01, #853300 R01AG081698 | Ph 4 | recruiting | Dosing of LT4 in Older Individuals |
| NCT05228184 | 20US-T414 | Ph 4 | terminated | Use of Tirosint®-SOL or Tablet Formulations of Levothyroxine in Pediatric Patients With Congenital Hypothyroidism (CH) |
| NCT05823012 results posted | XP-8121-120 | Ph 2 | completed | Study of XP-8121 For the Treatment of Adult Subjects With Hypothyroidism |
| NCT04878614 | IRB#20-002097 | Ph 4 | terminated | Comparison of Levothyroxine Formulation in Hypothyroid Patients With Enteral Feeding |
| NCT03281083 | MRN-01-NAFLD-01 | Ph 2 | terminated | Levothyroxine for Non-Alcoholic Fatty Liver Disease (NAFLD) |
| NCT00921050 | EN_LC_P136 | Ph 2, Ph 3 | completed | Subclinical Hypothyroidism and Mind in the Elderly |
Active Pipeline
Ongoing clinical trials by development phase
Key Completed Trials
Completed studies with published results, ranked by significance
Trial Timeline
Full development history with FDA approval milestones
Understanding FDA Approval Types
| Count | Type | What it means |
|---|---|---|
| - | ORIG | Original approval - drug first enters market |
| - | SUPPL - Efficacy | New indication (new disease/condition approved) |
| - | SUPPL - Labeling | Label text changes (warnings, dosing updates) |
| - | SUPPL - Manufacturing | Production changes (new facility) |
| - | SUPPL - Chemistry | Formulation changes (new dosage strength) |
Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.
LEVOXYL FDA Label Details
Indications & Usage
FDA Label (PDF)LEVOXYL is indicated for the treatment of Hypothyroidism; Thyroid Cancer.
WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS Thyroid hormones, including LEVOXYL, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffectiv...
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Data Sources
Data sourced from official FDA and NIH databases. Click links to verify on original sources.
How We Calculate These Metrics
Trial Activity Stage
Measures the current development activity pattern based on trial phases, status, and trends. Important: This measures R&D activity, not commercial lifecycle.
Trial statuses: "Active" means recruiting or ongoing. "Completed" means reached planned endpoint. "Terminated" means stopped early—often due to safety, efficacy, or business reasons.
- Growth: High proportion of early-phase trials (Phase 1/2), active development
- Expansion: Significant Phase 3 activity, approaching or pursuing approvals
- Mature: Substantial Phase 4 post-marketing studies
- Stable: Mixed phase distribution, steady development
- Declining: Low active trial ratio, reduced R&D investment