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Why Weight Loss After Stopping Methimazole Occurs?

It is always possible to contract a disease in the world we live in. Certain diseases are particularly dangerous and harm our bodies in other ways. A malfunctioning body system can produce antibodies that attack our body cells and cause diseases like Graves disease and Graves disorder, which cause Hyperthyroidism.

Why do we observe weight loss after stopping Methimazole? 

Methimazole has a weight gain effect because it cures Hyperthyroidism. When we stop using it, our diet returns to normal, and weight loss is noticeable, and a sudden weight loss will lead to many other serious health concerns.

How does Hyperthyroidism occur? It is essential to explain Graves disease since it is the leading cause of Hyperthyroidism, and you can use Methimazole to treat it.

Table of Content

Why is Methimazole Used?

It is used to treat Hyperthyroidism. It occurs when your thyroid gland produces excessive thyroxine. Several conditions can cause it, including Plummer’s disease, Graves’ disease, and thyroiditis.

The thyroid gland is a small butterfly looked gland located below Adam’s apple at the bottom of your neck. The thyroid gland impacts our health in a number of ways. Through thyroid hormones, every component of your metabolism regulates.

Thyroxine (T4) and triiodothyronine (T3) are primary thyroid hormones that affect all of your body’s cells.


Maintaining the rate at which you digest fats and carbohydrates, controlling your body temperature. It also influences your heart rate, and regulating protein synthesis are some of their functions. Also, the thyroid produces a hormone called calcitonin that controls calcium levels in the blood.

The following are some of the common symptoms of Hyperthyroidism.

  • Sweating
  • Patterns of menstruation may change.
  • Sensitivity to heat increases
  • Changes in bowel patterns.
  • Swelling at the base of the neck can occur if your thyroid gland (goiter) is enlarged
  • Fatigue
  • Weakness in muscles.
  • Sleeping difficulty.
  • Thinning of the skin.

You can treat Hyperthyroidism in several ways. The most favorable treatment for you will depend on your physical condition, age, the underlying cause of Hyperthyroidism, and the severity of your condition. Among the possible treatments are:

  • Radioactive Iodine: The doctor ingests the radioactive iodine by the mouth that causes the thyroid gland to shrink when absorbed through the mouth. The complications usually go away after several months. The body gets rid of excess radioactive iodine after several weeks or months.
  • Medications: The medicine prevents your thyroid gland from producing excess hormones, reducing hyperthyroidism symptoms. The medications contain Methimazole (Tapazole) and propylthiouracil. Some people discover that they can remove their ailment permanently. At the same time, others are likely to endure a relapse. Both pills can lead to liver damage, sometimes to death. Propylthiouracil has induced more cases of liver damage than Methimazole, so you should use it only if you cannot tolerate Methimazole.

How Does Methimazole Work?

Methimazole is an antithyroid drug. There is no excessive production of thyroid hormone by the thyroid gland. It is used to treat Hyperthyroidism (overactive thyroid gland). It is additionally used before thyroid surgery or radioactive iodine treatment.

Methimazole can also be used for functions no longer indexed on this remedy.

A primary mechanism of Methimazole’s action appears to be its interference with thyroid peroxidase (TPO), which is an essential step in thyroid hormone synthesis. 

However, the method by which Methimazole inhibits this process is unclear.6 TPO and hydrogen peroxide catalyze the conversion of iodide into iodine followed by incorporating this iodine into the three or five phenolic rings of tyrosine residues in thyroglobulin. 

One of the primary hormones produced by the thyroid gland is thyroglobulin, which degrades inside thyroid follicular cells to produce either thyroxine (T4) or triiodothyronine (T3).

Methimazole can also, without delay, inhibit TPO. However, it can also act as an aggressive substrate for that enzyme, with the result that it becomes iodinated itself and interferes with the iodination of thyroglobulin.

A second hypothesis is that Methimazole’s sulfa moiety might have interaction. Without delay with the iron atom in the center of TPO’s heme molecule, thereby inhibiting its ability to iodine tyrosine residues. In addition to methimazole binding to thyroglobulin without delay, direct inhibition of thyroglobulin itself has been proposed. These mechanisms are less well supported.

Side Effects

You should seek emergency medical attention if you experience any of the following symptoms: hives; challenging breathing; lips, tongue, throat, or swelling of your face.

Methimazole can also cause severe and sometimes deadly infections at some point during treatment. When you experience contamination symptoms, such as: contact your health practitioner right away. Stop using Methimazole and contact your health practitioner.

  • Headache
  • Feeling sleepy
  • Vomiting
  • Nausea
  • An upset stomach
  • Loss of hair
  • Decreased sense of taste
  • Increase in weight

Weight Loss After Stopping Methimazole?

As a result of Hyperthyroidism, the body loses weight; however, when Methimazole is used to treat Hyperthyroidism, the body weight increases.

  • Firstly, the body is recovering from a disease that caused the body to lose about 10 kg when Hyperthyroidism was cured due to a regular diet and average hormone production.
  • Furthermore, each medicine works differently. For example, some can increase your appetite, while others can decrease it. Therefore, if you feel hungry while taking Methimazole, you will eat more, leading to weight gain.
  • Methimazole, the main reason for increasing weight during treatment of Hyperthyroidism, causes about 10% of patients to gain weight during and after the treatment. Since Hyperthyroidism is treated with Methimazole, this is the leading cause of weight gain during treatment.

Weight Loss After Reducing Use Of Methimazole

Methimazole is a reason for the increasing weight of patients during hyperthyroidism treatment. Still, when patients begin to reduce the usage of Methimazole with time, their weight may decrease. Weight loss is average as long as it is not excessive. This is not a cause for concern.

In contrast, if your weight declines exponentially, you need to take it seriously because this type of weight loss is not suitable for your body. Your body will lose nutrients at an unbelievable rate.  

The reason for regular weight loss is the stable amount of hormones produced.

After stopping Methimazole, there could be a variety of reasons for weight loss. Some of the important ones are below:

  • Stop using Methimazole before proper treatment:  If you stop taking Methimazole before Hyperthyroidism is cured, you will lose a lot of weight. When a disease is not thoroughly treated and left unchecked, there are many possibilities for the disease to occur again. Then it would be good to consult your healthcare provider and have yourself diagnosed to continue your treatment.
  • When body metabolism gets normalized:  Hyperthyroidism causes an imbalance of metabolism throughout the body. Over time and with the use of medicines, a change in the weight of your body is observed. At first, your weight decreases very rapidly due to Hyperthyroidism. After you start the medicine, Methimazole will help you regain weight, but you may experience a slight weight loss after it is stopped. This is not dangerous, and it is a normal phenomenon.

When To Consult A Doctor?

When we observe that your weight loss is not average, or if your body is losing weight exponentially. 

And if it is along with weakness, fever, sleeping problems, or changes in bowel habits, we recommend that you consult your doctor. The doctor will diagnose you and recommend the next step.


Question: What happens when you stop using Methimazole?

Answer: The absence or discontinuation of antithyroid medications will produce unbelievable and undesirable effects. The lack of proper medication will lead to myxoedema if the condition is hypothyroidism, and if the condition is hypothyroidism, then it will lead to a thyroid storm.

Question: How much weight did patients gain on using Methimazole?

Answer: The most effective treatment for Hyperthyroidism is completely blocking the thyroid glands. According to a study, almost 42 people gained about 12 pounds by blocking their thyroid glands.

Question: Why am I gaining weight while taking thyroid medication?

Answer:  The thyroid hormone interacts with many tissues in the body, including the brain, fat cells, muscle, liver, and pancreas. A low thyroid stage causes your metabolism to slow down, which also causes you to burn less energy, even when you’re resting. Additionally, you are less likely to burn fat for energy, leading to weight gain.


Based on everything we have discussed, it is clear that if you do not want any sudden weight loss after stopping Methimazole. It is essential to identify the reasons behind weight loss. 

It would be better to take preventative measures to avoid such a situation. It is best to consult your healthcare provider if there is excessive weight loss.

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