Need help or have questions about your order? Call 510-991-8265Questions about your order? Call 510-991-8265

Sign InShop GLPs
Shop GLPs

Methimazole (Tapazole) Appetite & Cravings Changes: What Patients and Clinicians Need to Know

By
Published Updated Last reviewed
4 linked public sourcesEditorial, sourcing, and corrections policy

At a glance

  • Action / inhibits thyroid hormone synthesis and does not inactivate T4 or T3 already stored or circulating [1]
  • Appetite loss / anorexia is listed as a symptom that should prompt liver testing [1]
  • Minor reactions / nausea, vomiting and stomach upset are listed [1]
  • Over-treatment / can cause hypothyroidism; TSH and free T4 are monitored with dose adjustment [1]
  • Older patients with hyperthyroidism / increased appetite less frequent than in younger patients; anorexia more frequent, 32% vs 4% [2]

Does methimazole act on appetite directly?

The label describes one action: methimazole inhibits the synthesis of thyroid hormones. It does not inactivate thyroxine and triiodothyronine already stored in the thyroid or circulating in the blood, and does not interfere with thyroid hormone given by mouth or injection [1].

Do appetite signals interact with the thyroid?

A review of thyroid hormone and metabolism describes the thyroid gland as regulated by TRH and TSH, with additional central modulation by nutritional signals such as leptin and by peptides that regulate appetite [3]. This describes appetite signals acting on thyroid regulation. It does not show that methimazole directly changes hunger or cravings.

Age and appetite symptoms in hyperthyroidism

A prospective cohort at a French university hospital compared 84 patients with newly diagnosed overt hyperthyroidism: 34 aged 70 or older (mean age 80.2) and 50 aged 50 or younger (mean age 37.4) [2]. Increased appetite was one of seven classical signs that were significantly less frequent in the older group (P<0.001). Anorexia ran the other way: 32% in the older group versus 4% in the younger (P<0.001) [2]. Tachycardia, fatigue and weight loss were each found in more than 50% of the older patients [2]. These patients were being assessed at diagnosis, so the study describes the disease rather than the effect of methimazole.

When appetite loss needs attention

The label lists anorexia, itching and right upper quadrant pain as symptoms suggestive of hepatic dysfunction, and says these should prompt evaluation of liver function (bilirubin, alkaline phosphatase) and hepatocellular integrity (ALT, AST) [1]. It counts hepatic transaminase values above 3 times the upper limit of normal as clinically significant evidence of liver abnormality [1]. The label also states that the risk of hepatotoxicity appears to be less with methimazole than with propylthiouracil, especially in children [1]. Nausea, vomiting and epigastric distress are listed among the minor adverse reactions [1].

Over-treatment and the labs the label uses

The label states that methimazole can cause hypothyroidism, which requires routine monitoring of TSH and free T4 with dose adjustment to keep a euthyroid state [1].

Frequently asked questions

Does methimazole directly affect appetite?
The label describes methimazole as inhibiting thyroid hormone synthesis and says it does not inactivate thyroxine or triiodothyronine already stored or circulating [1]. It describes no direct effect on hunger.
Can methimazole cause loss of appetite?
Anorexia is listed in the label among symptoms suggestive of hepatic dysfunction that should prompt liver function testing, along with itching and right upper quadrant pain [1]. Nausea, vomiting and epigastric distress are listed as minor adverse reactions [1].
Do older patients get the same hunger as younger ones?
Less often. In a study of 84 newly diagnosed hyperthyroid patients, increased appetite was significantly less frequent at age 70 and older than at 50 and younger, while anorexia was more frequent (32% versus 4%) [2].
Which symptoms does the label say to report right away?
The label says patients should immediately report symptoms suggestive of agranulocytosis, such as fever or sore throat, because agranulocytosis is potentially life-threatening [1]. Anorexia, itching and right upper quadrant pain should prompt liver testing [1].

References

  1. U.S. National Library of Medicine, DailyMed. Methimazole tablets USP (Chartwell RX) prescribing information. Methimazole tablets USP (Chartwell RX) label
  2. Trivalle C, Doucet J, Chassagne P, Landrin I, Kadri N, Menard JF, et al. Differences in the signs and symptoms of hyperthyroidism in older and younger patients. J Am Geriatr Soc. 1996;44(1):50-3. Differences in the signs and symptoms of hyperthyroidism in older and younger patients
  3. Mullur R, Liu YY, Brent GA. Thyroid hormone regulation of metabolism. Physiol Rev. 2014;94(2):355-82. Thyroid hormone regulation of metabolism
  4. Fliers E, Unmehopa UA, Alkemade A. Functional neuroanatomy of thyroid hormone feedback in the human hypothalamus and pituitary gland. Mol Cell Endocrinol. 2006;251(1-2):1-8. Functional neuroanatomy of thyroid hormone feedback in the human hypothalamus and pituitary gland
Evidence overview for methimazole: Methimazole (Tapazole) Appetite & Cravings Changes: What Patients and Clinicians Need to Know