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Does Tapazole (methimazole) cause side effects?
Tapazole (methimazole) is an antithyroid drug used to treat an overactive thyroid gland (hyperthyroidism). It also is used to decrease symptoms of hyperthyroidism in preparation for surgical removal of the thyroid gland or before inactivating the thyroid gland with radioactive iodine.
Long-term use of Tapazole may lead to a remission of hyperthyroidism. Grave's disease is the most common cause of hyperthyroidism. Grave's disease is an autoimmune disease resulting from antibodies that attach to receptors on thyroid hormone-producing cells in the thyroid gland and trigger overproduction of thyroid hormone.
An enzyme (peroxidase) produces thyroid hormones, i.e., thyroxine (T4) and triiodothyronine (T3), by combining iodine with a protein called thyroglobulin. Tapazole prevents iodine and peroxidase from their normal interactions with thyroglobulin to form T4 and T3.
This action decreases thyroid hormone production. Tapazole also interferes with the conversion of T4 to T3. Since T3 is more potent than T4, this also reduces the activity of thyroid hormones.
Common side effects of Tapazole include
- abnormal hair loss,
- skin pigmentation,
- loss of taste,
- joint or muscle aches,
- numbness, and
Serious side effects of Tapazole include
- decreased white blood cells (agranulocytosis – symptoms include infections of the throat, the gastrointestinal tract, and skin, with an overall feeling of illness and fever) and
- blood platelets (thrombocytopenia - may lead to problems with excessive bleeding), and hepatitis and death of liver cells (hepatic necrosis).
- Hyperthyroidism increases elimination of beta-blockers. Correcting hyperthyroidism will cause less elimination of beta-blockers so the dose of beta-blockers may require reduction when hyperthyroidism is corrected. A similar reaction may also occur with digoxin and theophylline.
What are the important side effects of Tapazole (methimazole)?
Methimazole is generally well-tolerated with side effects occurring in 3 out of every 100 patients. The most common side effects are related to the skin and include:
Other common side effects are:
Less common but more serious side effects include a decrease in white blood cells (agranulocytosis) and blood platelets (thrombocytopenia). Symptoms and signs of agranulocytosis include infections of the throat, the gastrointestinal tract, and skin with an overall feeling of illness and fever.
Since platelets are important for the clotting of blood, thrombocytopenia may lead to problems with excessive bleeding. Hepatitis and death of liver cells (hepatic necrosis) have rarely been associated with methimazole.
Tapazole (methimazole) side effects list for healthcare professionals
Major adverse reactions (which occur with much less frequency than the minor adverse reactions) include
- inhibition of myelopoieses (agranulocytosis, granulocytopenia, thrombocytopenia, and aplastic anemia),
- drug fever,
- a lupus-like syndrome,
- insulin autoimmune syndrome (which can result in hypoglycemic coma),
- hepatitis (jaundice may persist for several weeks after discontinuation of the drug),
- periarteritis, and
Nephritis occurs very rarely.
Minor adverse reactions include
What drugs interact with Tapazole (methimazole)?
Due to potential inhibition of vitamin K activity by methimazole, the activity of oral anticoagulants (e.g., warfarin) may be increased; additional monitoring of PT/INR should be considered, especially before surgical procedures.
β-Adrenergic Blocking Agents
Hyperthyroidism may cause an increased clearance of beta blockers with a high extraction ratio. A dose reduction of beta-adrenergic blockers may be needed when a hyperthyroid patient becomes euthyroid.
Serum digitalis levels may be increased when hyperthyroid patients on a stable digitalis glycoside regimen become euthyroid; a reduced dosage of digitalis glycosides may be needed.
Theophylline clearance may decrease when hyperthyroid patients on a stable theophylline regimen become euthyroid; a reduced dose of theophylline may be needed.
Tapazole (methimazole) is an antithyroid drug used to treat an overactive thyroid gland (hyperthyroidism) and decrease symptoms of hyperthyroidism in preparation for surgical removal. Common side effects of Tapazole include rash, itching, hives, abnormal hair loss, skin pigmentation, swelling, nausea, vomiting, heartburn, loss of taste, joint or muscle aches, numbness, and headache. Using Tapazole during pregnancy could harm a fetus. Tapazole is excreted in breast milk and may potentially cause harm to the infant.
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Related Disease Conditions
Hypothyroidism is any state in which thyroid hormone production is below normal. Normally, the rate of thyroid hormone production is controlled by the brain by the pituitary gland. Hypothyroidism is a very common condition and the symptoms of hypothyroidism are often subtle but may include constipation, memory loss, hair loss, and depression. There are a variety of causes of hypothyroidism, and treatment depends on the cause.
Thyroid Disorders Symptoms and Signs
Thyroid diseases and disorders are caused because the body either makes too much or too little thyroid hormones, which are necessary for vital functions of the body. Thyroid disease and disorder symptoms and signs depend on the type of the thyroid problem. Examples include heat or cold intolerance, sweating, weight loss or gain, palpitations, fatigue, dry skin, constipation, brittle hair, joint aches and pains, heart palpitations, edema, feeling bloated, puffiness in the face, reduced menstrual flow, changes in the frequency of bowel movements and habits, high cholesterol, hoarseness, brittle hair, difficulty swallowing, shortness of breath, a visible lump or swelling in the neck, tremors, memory problems, depression, nervousness, agitation, irritability, or poor concentration. Thyroid problems are more common in women.
There are several types of thyroid disorders including hypothyroidism, hyperthyroidism, goiters, thyroid nodules, and thyroid cancer. Symptoms vary by condition. Diagnosis is made with blood tests, scans, ultrasound, or biopsy. Treatments depend on the disorder and can include medication or surgery.
Hyperthyroidism is an excess of thyroid hormone due to an overactive thyroid gland. Symptoms can include increased heart rate, weight loss, heart palpitations, frequent bowel movements, depression, fatigue, fine or brittle hair, sleep problems, thinning skin, and irregular vaginal bleeding. Graves' disease is the most common cause of hyperthyroidism. Many other health problems or taking excess thyroid hormone medication can cause an overactive thyroid gland. Treatment for the condition is with medication, radioactive iodine, thyroid surgery (rarely), or reducing the dose of thyroid hormone. No diet has been shown to treat hyperthyroidism or its symptoms and signs.
Second Source article from Government
Hashimoto's thyroiditis or chronic lymphocytic thyroiditis is an autoimmune disorder causing inflammation of the thyroid gland. Hashimoto's thyroiditis is a type of hypothyroidism and is the most common cause of hypothyroidism in the US. Symptoms of Hashimoto's thyroiditis may include dry skin, fatigue, weight gain, feeling cold, excessive sleepiness, dry skin, dry coarse hair, difficulty swallowing, a lump in the front of the throat, muscle cramps, mood changes, vague aches and pains, problems concentrating, leg swelling, constipation, and depression. There is no cure for Hashimoto’s thyroiditis. Diet changes, natural supplements, vitamins, or other natural products will not treat Hashimoto’s thyroiditis. Treatment for the autoimmune disorder is with thyroid hormone replacement therapy, which will be necessary for the rest of the person’s life.
Hypothyroidism During Pregnancy
Hypothyroidism during pregnancy can be treated with synthetic thyroid hormones to maintain the proper thyroid hormone balance. Hypothyroidism symptoms and signs include fatigue, weight gain, lethargy, and constipation. Treatment of hypothyroidism in pregnant women is important because inadequate levels of thyroid hormones may affect the fetus and child during growth and development.
Thyroid nodules are the most common endocrine problem in the United States. The term thyroid nodule refers to any abnormal growth that forms a lump in the thyroid gland. The vast majority of thyroid nodules are benign.
Thyroiditis is the inflammation of the thyroid gland. The inflamed thyroid gland can release an excess of thyroid hormones into the blood stream, resulting in a temporary hyperthyroid state. Some forms of thyroiditis can be diagnosed based on tenderness and enlargement of the thyroid gland. A thyroid scan sometimes is used in making the diagnosis. Thyroiditis can also be diagnosed with a biopsy of the thyroid gland.
There are four major types of thyroid cancer: papillary, follicular, medullary, and anaplastic thyroid cancer. Tumors on the thyroid are referred to as thyroid nodules. Symptoms of thyroid cancer include swollen lymph nodes, pain in the throat, difficulty swallowing, hoarseness, and a lump near the Adam's apple. Treatment usually involves chemotherapy, surgery, radioactive iodine, hormone treatment or external radiation and depends upon the type of thyroid cancer, the patient's age, the tumor size, and whether the cancer has metastasized.
Hyperparathyroidism is a disorder of the parathyroid glands. There are two types of hyperparathyroidism, primary and secondary. When the parathyroid glands produce too much hormone, hyperparathyroidism is the resulting condition. Most cases of hyperparathyroidism have no evident cause. Signs and symptoms of hyperparathyroidism include fatigue, weakness, depression, loss of appetite, nausea, vomiting, constipation, or confusion. Increased calcium and phosphorous excretion may cause kidney stones. The main treatment of hyperparathyroidism is surgery (parathyroidectomy).
The thyroid gland is a butterfly-shaped gland located in the front of the neck. The thyroid gland produces important thyroid hormones, which are produced by the pituitary gland. There are six types of thyroid problems. Home remedies, medications, surgery, lifestyle changes, and surgery. Usually, most types of thyroid problems can be managed with home remedies, medications, lifestyle changes (diet, yoga), and surgery.
What Happens If Hypothyroidism Is Left Untreated?
If hypothyroidism is not treated, it can lead to various complications.
In hypoparathyroidism, the parathyroid gland does not produce enough parathyroid hormone. Causes of hypoparathyroidism include injury to the parathyroid glands, autoimmune disorder association, or may be present ab birth. Symptoms of hypoparathyroidism include: tingling fingers, toes, and lips, brittle nails, dry, coarse skin, dry hair; memory loss, headaches, severe muscle cramps, cataracts, malformed teeth, and convulsions. Treatment of hypoparathyroidism is to restore the calcium and phosphorus to normal levels in the body.
Causes for Hypothyroidism
Hypothyroidism may be caused by several reasons. The causes are broadly divided into primary and secondary causes.
What Are the Warning Signs of Thyroid Cancer?
Thyroid cancer arises from the cells of the thyroid gland. The thyroid is a butterfly-shaped gland located in the front of the neck, just below Adam's apple. Warning signs of thyroid cancer include a lump in the neck, trouble swallowing, trouble breathing, voice changes, cough, weight loss, and palpitations.
What Happens to Your Body When You Have Thyroid Cancer?
Thyroid cancer arises from the cells of the thyroid gland. The thyroid is a butterfly-shaped gland located in the front of the neck, just below Adam's apple. Common symptoms and signs of thyroid cancer may include a lump in the neck, trouble swallowing, trouble breathing, voice changes, cough, weight loss, and palpitations.
Complications Of Hypothyroidism: Fertility, Weight And More
The thyroid gland is a small butterfly-shaped gland located in the front of the neck. Hypothyroidism is a medical condition in which the thyroid gland becomes underactive.
What Causes Hypothyroidism?
Hypothyroidism results when the thyroid gland fails to produce enough hormones. Hypothyroidism may be due to a number of factors.
Treatment & Diagnosis
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Medications & Supplements
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.