Levothyroxine: the public record

Selected the most recently revised prescription label for this single ingredient from an original manufacturer, preferring a brand-name application. Checked which sections exist and quoted headings and sentences exactly as printed.

Scope: One label: the newest prescription label for single-ingredient levothyroxine from an original manufacturer

Read from one label. Labels for other brands, strengths or forms of the same ingredient can differ. A missing section heading does not mean there is no guidance. Read the full label before relying on it.

Selected applications with a product whose only active ingredient is this substance, then counted approved original and supplemental submissions. The earliest approved original submission is the first approval.

Scope: Applications with a single-ingredient levothyroxine product in Drugs@FDA, all sponsors and strengths

Older approvals can be missing dates, and tentative approvals are not counted. An approved application does not mean the product is currently marketed.

Selected Orange Book products whose only active ingredient is this substance, then counted applications by type and the distinct patents and exclusivities listed against them. Expired patents are left out.

Scope: All single-ingredient levothyroxine products in the Orange Book, every brand and strength, files dated 2026-10-09

An approved generic or an expired patent does not show that a generic is on sale. Launch timing also depends on litigation, settlements and supply. Biologics and compounded products are not in the Orange Book.

Summed the national rows for every brand and generic row with this generic name. Claims under 65 are total claims minus claims for enrollees 65 and over.

Scope: National Part D claims for single-ingredient levothyroxine products, 2024, split at age 65

Medicare mostly covers people 65 and over, so this split describes Medicare enrollees and not use in the general population.

Summed total spending and claims over every brand and generic row with this generic name in the CMS file, using the Overall manufacturer rows. Combination products excluded. Average per claim is spending divided by claims.

Scope: Every single-ingredient levothyroxine product in Part D (Levothyroxine Sodium*, Synthroid, Tirosint), 2024.

Gross drug cost before manufacturer rebates, so net cost is lower. Part D excludes some uses by law (for example erectile dysfunction, weight loss and hair growth), so claims reflect covered uses only. Compounded products are not included.

Matched each Medicaid product code to the FDA NDC Directory by labeler and product code, kept finished single-ingredient products, then summed prescriptions and reimbursement by state. National roll-up and suppressed rows dropped.

Scope: All single-ingredient levothyroxine products in the FDA NDC Directory, fee-for-service and managed care, 2025

Counts under 11 are suppressed by CMS and left out, so totals are a floor. Amounts are before rebates. Differences between states reflect programme size and coverage rules. Compounded products are not included.

Matched NADAC product codes to the FDA NDC Directory, kept finished single-ingredient products, and listed the product descriptions with the most package codes. The earlier price is the same package code in the file one year before.

Scope: Generic versions of levothyroxine in the weekly NADAC file of 2026-11-11, compared with the file of 2025-11-12

NADAC is the average invoice price retail pharmacies pay, from a voluntary survey. It leaves out rebates, dispensing fees and markups, and it is not what a patient or insurer pays. Compounded products are not surveyed.

Counted FAERS reports listing this active substance, then the reaction terms named most often. A report can name several reactions, and a term can describe the illness being treated and not an effect of the drug. Terms about product use or complaints rather than symptoms (for example drug ineffective) were left out of the list.

Scope: Reports where FDA recorded levothyroxine as a single-ingredient active substance (any brand), all years to 2026-10-28

FAERS reports are unverified and do not prove the drug caused the event. Reporting rises with use, publicity and lawsuits, so these counts cannot give rates or risks and cannot be compared between drugs.

Counted enforcement report entries matched by FDA's listed active substance, or by the name in the product description where FDA lists none. Reasons were grouped by keywords in FDA's stated reason.

Scope: Recalls of single-ingredient levothyroxine products, plus compounded or unlisted products whose description names it

Each recall covers specific lots from one firm and is not a statement about every product with this ingredient. One event can appear as several entries, one per product.

Searched the ClinicalTrials.gov intervention field for the name, downloaded every matching record and counted by overall status and phase. Combined phases are counted under the higher phase. Phase not applicable covers observational, device and behavioural studies.

Scope: Studies whose intervention field matches levothyroxine, any condition, any country, all statuses

A registered study is not a result. Counts include studies where the drug is a comparator or background treatment, and studies that never finished or reported.