- Body system
- Endocrine
- Brand names
- Tapazole
What is Methimazole used for?
- Hyperthyroidism (Graves disease, toxic nodular goiter)
- Preparation for thyroid surgery or radioactive iodine
How Methimazole works
Thioamide: blocks the thyroid gland's production of new thyroid hormone.
Common side effects
- Rash and itching
- Nausea
- Joint pain
- Altered taste
Report right away
- Fever, sore throat or mouth sores (agranulocytosis)
- Yellow skin or eyes, dark urine, right upper abdominal pain (liver injury)
Nursing considerations for Methimazole
- Monitor TSH and free T4, and the CBC with differential if fever or sore throat appear.
- Propylthiouracil is usually preferred in the first trimester of pregnancy; methimazole is preferred otherwise.
- Watch for signs of hypothyroidism from overtreatment: fatigue, cold intolerance, weight gain.
Patient teaching
- Report sore throat, fever or infection right away.
- It takes several weeks to feel the full effect.
This card does not list doses. Use the prescriber's order, the product label and a current drug reference for dosing, and follow your facility's policies.
Thyroid and antithyroid drugs practice questions
NCLEX-style questions on the class Methimazole belongs to.
3 questions. Choose an answer to see the rationale.
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When should a patient take levothyroxine?
Show answer
Answer B: On an empty stomach 30 to 60 minutes before breakfast Food, calcium and iron reduce absorption. Taking it consistently on an empty stomach gives stable levels.
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A patient taking methimazole reports fever and a sore throat. What is the priority?
Show answer
Answer C: Notify the provider and check the CBC: possible agranulocytosis Agranulocytosis is a serious adverse effect of thioamides; fever and sore throat are the warning signs.
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Which finding suggests the levothyroxine dose is too high?
Show answer
Answer A: Palpitations and insomnia Too much thyroid hormone causes signs of hyperthyroidism, such as palpitations, nervousness and insomnia.
Frequently asked questions
What is Methimazole used for?
Hyperthyroidism (Graves disease, toxic nodular goiter); Preparation for thyroid surgery or radioactive iodine.
What drug class is Methimazole?
Methimazole belongs to the class thyroid and antithyroid drugs. Thioamide: blocks the thyroid gland's production of new thyroid hormone.
What are the nursing considerations for Methimazole?
Monitor TSH and free T4, and the CBC with differential if fever or sore throat appear. Propylthiouracil is usually preferred in the first trimester of pregnancy; methimazole is preferred otherwise.
What should patients report while taking Methimazole?
fever, sore throat or mouth sores (agranulocytosis); yellow skin or eyes, dark urine, right upper abdominal pain (liver injury).