Public record
Methimazole: the public record
Each table is computed from the named federal dataset as of its data date; the method is under each one.
Label
FDA label facts for methimazole
The FDA label read for methimazole (Methimazole, application ANDA040547) was last revised on 2026-08-20. It carries no boxed warning. Of the 4 population sections checked, 3 are present: pregnancy, lactation, pediatric use.
| Measure | Value | Note |
|---|---|---|
| Label revision date | 2026-08-20 | |
| Label read | Methimazole | ANDA040547, generic application |
| Boxed warning | No | |
| Pregnancy section | Present | |
| Lactation section | Present | |
| Pediatric use section | Present | |
| Geriatric use section | Not present |
How this was calculated
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.
One label: the newest prescription label for single-ingredient methimazole 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.
Approvals
FDA approval history for methimazole
The earliest FDA approval on file for a methimazole product is 1950-06-21. Drugs@FDA lists 12 applications for it and 53 approved supplements, the most recent on 2025-08-26.
| Measure | Value | Note |
|---|---|---|
| Earliest FDA approval on file | 1950-06-21 | |
| Applications with an approval on file | 12 | |
| New drug applications (NDA) | 1 | |
| Generic applications (ANDA) | 11 | |
| Approved supplements | 53 | label, manufacturing and efficacy changes |
| Most recent supplement approval | 2025-08-26 | |
| Sponsoring companies | 12 |
How this was calculated
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.
Applications with a single-ingredient methimazole 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.
Patents and generics
Patents and generic approvals for methimazole
The FDA Orange Book lists 11 approved generic applications for methimazole, the first approved on 2000-03-29. No unexpired patents are listed for it.
| Measure | Value | Note |
|---|---|---|
| Brand-name applications (NDA) | 1 | |
| Approved generic applications (ANDA) | 11 | first approved 2000-03-29 |
| Companies with a generic not marked discontinued | 8 | |
| Listed patents not yet expired | 0 | |
| Earliest approval date on file | before 1982 | |
| Products not marked discontinued | 16 of 25 |
How this was calculated
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.
All single-ingredient methimazole 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.
Medicare Part D
Medicare Part D spending on methimazole
Medicare Part D spending on methimazole products was $10.6M in 2024 across 943,504 claims, compared with $13.3M in 2023 (-20.2%). Average spending per claim was $11.24, before rebates.
| Measure | Value |
|---|---|
| Total spending, 2024 | $10.6M |
| Total spending, 2023 | $13.3M |
| Change in spending, 2023 to 2024 | -20.2% |
| Claims (prescription fills), 2024 | 943,504 |
| Average spending per claim, 2024 | $11.24 |
How this was calculated
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.
Every single-ingredient methimazole product in Part D (Methimazole), 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.
Adverse event reports
Most reported events in FDA adverse event reports for methimazole
Through 2026-10-28, FDA had received 9,380 adverse event reports for methimazole, 7,048 of them marked serious by the reporter. The symptom terms named most often were fatigue (524), hyperthyroidism (489) and nausea (447).
| Measure | Value | Note |
|---|---|---|
| All reports received | 9,380 | |
| Reports the reporter marked serious | 7,048 | death, hospitalisation, disability or similar outcome |
| Fatigue | 524 reports | |
| Hyperthyroidism | 489 reports | |
| Nausea | 447 reports | |
| Diarrhoea | 419 reports | |
| Headache | 382 reports |
How this was calculated
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.
Reports where FDA recorded methimazole 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.
Clinical studies
Registered clinical studies of methimazole
ClinicalTrials.gov lists 40 registered studies that name methimazole as an intervention as of 2026-11-11. Of these, 4 are recruiting, 16 are completed and 4 are phase 3 studies.
| Measure | Value |
|---|---|
| Registered studies | 40 |
| Recruiting now | 4 |
| Not yet recruiting | 2 |
| Completed | 16 |
| Terminated, withdrawn or suspended | 6 |
| Phase 3 (including phase 2/3) | 4 |
| Phase 2 (including phase 1/2) | 7 |
| Phase 1 | 2 |
How this was calculated
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.
Studies whose intervention field matches methimazole, 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.
Articles on Methimazole
- Methimazole (Tapazole) Compounded vs Branded: A Clinical Comparison
- Methimazole Missed Dose: What the Label Says About Dosing
- Methimazole (Tapazole) Pharmacokinetics: Absorption, Distribution, Metabolism, and Excretion
- Methimazole (Tapazole) Safety Signals & FDA Actions
- Methimazole (Tapazole) Accelerated Titration: How to Adjust Doses Faster and Safely
- Methimazole (Tapazole) Hair and Skin Changes: What Patients and Clinicians Need to Know