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General Medication Fact Sheet for Methimazole
| Field | Information |
|---|---|
| Generic Name | Methimazole |
| Brand Name Versions | Tapazole |
| Purpose | Antithyroid agent used to treat hyperthyroidism |
| Mechanism of Action | Inhibits thyroid peroxidase, reducing the production of thyroid hormones (T3 and T4) |
| Dosage Forms | Oral tablets |
| Available Strengths | 5 mg, 10 mg |
| Dosage Frequency | Typically once daily or divided into multiple doses, as directed by a healthcare provider |
| Common Side Effects | Skin rash, itching, hair loss, nausea, vomiting, heartburn, joint pain |
| Serious Side Effects | Severe allergic reactions, liver problems, decreased white blood cell count (agranulocytosis), hypothyroidism |
| Drug Interactions | Anticoagulants (e.g., warfarin), digoxin, theophylline |
| Important Notes | Report any signs of infection (fever, sore throat) immediately; regular blood tests are required to monitor thyroid function and blood cell counts |
| Storage | Store at room temperature away from moisture and light |
| Missed Dose | Take as soon as you remember; skip if it’s almost time for your next dose. Do not double the dose. |
| Alternatives | Propylthiouracil (PTU), Radioactive iodine (I-131), Thyroidectomy (surgical removal of the thyroid gland) |
Methimazole Alternatives
| Medication | Mechanism of Action | Notes |
|---|---|---|
| Propylthiouracil (PTU) | Inhibits thyroid peroxidase and conversion of T4 to T3 | Often used in the first trimester of pregnancy due to potential risks associated with methimazole. |
| Radioactive iodine (I-131) | Destroys thyroid cells | Administered orally; may lead to permanent hypothyroidism. |
| Thyroidectomy (surgical removal of the thyroid gland) | Surgical removal of all or part of the thyroid gland | Usually reserved for patients with large goiters, thyroid cancer, or those who cannot tolerate antithyroid drugs. |
Methimazole Side Effects
| Common Side Effects | Serious Side Effects |
|---|---|
| Skin rash | Severe allergic reactions (hives, swelling, difficulty breathing) |
| Itching | Liver problems (jaundice, dark urine, abdominal pain) |
| Hair loss | Decreased white blood cell count (agranulocytosis) |
| Nausea | Hypothyroidism |
| Vomiting | Aplastic Anemia |
Methimazole Dosage Guide
| Condition | Starting Dose | Maintenance Dose | Administration Notes |
|---|---|---|---|
| Hyperthyroidism (Mild) | 5 mg daily | 2.5 – 5 mg daily | Adjust based on thyroid function tests. |
| Hyperthyroidism (Moderate) | 10 mg daily | 5 – 10 mg daily | Adjust based on thyroid function tests. |
| Hyperthyroidism (Severe) | 15-20 mg daily | 5 – 15 mg daily | Adjust based on thyroid function tests. Higher doses may be divided. |
Methimazole Price With And Without Insurance
| Purchase Context | Estimated Price |
|---|---|
| With Insurance | $20 – $75 |
| Without Insurance (U.S.) | $600 |
| From CPS | $25 |
