Methimazole (brand name Tapazole), is commonly prescribed to those who have hyperthyroidism and Graves’ disease. In most cases it is effective in reducing thyroid hormone levels, and while it’s not doing anything for the cause of the problem, it can help to prevent someone from receiving radioactive iodine (RAI) or thyroid surgery while the underlying cause of the condition is being addressed. However, not everyone is able to tolerate Methimazole, and if someone has a negative reaction to Methimazole, there is a good chance the endocrinologist will recommend RAI or thyroid surgery.
Methimazole, along with other thionamide-derived antithyroid drugs, have been used for over half a century. A common starting dosage is 20 mg per day, although if someone has a more severe case of hyperthyroidism then larger doses might be prescribed (i.e. 40 mg/day). Most endocrinologists will recommend Methimazole for 12 to 18 months, assuming the person isn’t experiencing any severe side effects, or other problems, including elevation of the liver enzymes.
As for how Methimazole works, it inhibits an enzyme called thyroperoxidase, which is important in the synthesis of thyroid hormone. It specifically inhibits the metabolism of iodide and the iodination of tyrosine residues, which in turn prevents the synthesis of both T4 and T3 (1) [1].
Potential Side Effects of Methimazole
Here are some of the side effects people can experience when taking Methimazole (2) [2] (3) [3]:
- Changes in taste
- Dizziness
- Hair loss
- Headaches
- Hives
- Itching
- Joint pain and swelling
- Nausea
- Rashes
- Vomiting
More serious side effects include the following (3) [3]:
- Blood in your urine or stools
- Clay-colored stools
- Dark urine
- Fever
- Jaundice (yellowing of the skin or eyes)
- Loss of appetite
- Severe blistering, peeling, and red skin rash
Two Additional Complications Associated With Methimazole
Agranulocytosis. This is a term used to describe a severe reduction in the production of white blood cells. This is more likely to affect those who take high doses of Methimazole. Some patients with agranulocytosis will present with signs and symptoms of an infection, including a high fever and a sore throat (4) [4].
Elevated liver enzymes. This is more commonly associated with Propylthiouracil (PTU), but over the years I’ve had numerous patients with hyperthyroidism whose liver enzymes were elevated when taking Methimazole or Carbimazole. You might want to check out an article I wrote entitled “How To Decrease Elevated Liver Enzymes In Hyperthyroidism and Graves’ Disease [5]“. In the article I discuss when you should be concerned about elevated liver enzymes, and some strategies to decrease them.
What Alternatives Are There To Methimazole?
As I mentioned in the opening paragraph, if someone is unable to take Methimazole, it’s common for their endocrinologist to recommend radioactive iodine or thyroid surgery. However, there are three treatment options you should consider before getting your thyroid gland ablated or surgically removed:
Option #1: Try to get a prescription for Propylthiouracil (PTU). The downside of PTU is that it can be harsher on the liver than Methimazole, and approximately 50% of those who are unable to tolerate Methimazole will also be unable to tolerate PTU. That being said, it still might be worth giving PTU a try, as while it might produce similar side effects as Methimazole, there is also a chance that you might be fine taking it, and at the very least it can buy you some time while you are trying to address the underlying cause of your condition.
Option #2: Consider natural antithyroid agents. Many reading this know that when I was diagnosed with Graves’ disease I didn’t take antithyroid medication. Instead, I took an antithyroid herb called bugleweed to manage my hyperthyroid symptoms. Although bugleweed isn’t always potent enough to lower the thyroid hormone levels, it’s definitely worth a try before resorting to extreme treatment methods such as RAI and thyroid surgery. It’s also important to mention that the quality of the herb is important, and you should consider taking a stronger extract ratio. For more information on bugleweed and other herbs that can help manage the hyperthyroid symptoms, I would read a blog post entitled “Which Are The Best Herbs For Managing The Symptoms Of Hyperthyroidism & Graves’ Disease? [6]”.
Option #3: Low dose naltrexone (LDN). This option should be considered for those people with Graves’ disease, and not other types of hyperthyroid conditions (i.e. toxic multinodular goiter, subacute thyroiditis, etc.). Naltrexone is an FDA-approved medication, and it was discovered that low dose naltrexone [7] (LDN) has immune-modulating effects that can benefit many people with autoimmune conditions. While there are no studies I’m aware of that specifically show that LDN can help people with Graves’ Disease, over the years I have had some people with Graves’ disease successfully use LDN to manage their symptoms while addressing the underlying cause of their condition.
If LDN can modulate the immune system and effectively manage the hyperthyroid symptoms, then why don’t I recommend it more frequently to my patients with Graves’ disease? There are a few reasons for this. The main reason is because while it’s not harsh on the body like Methimazole, it’s also not as effective in managing the hyperthyroid symptoms. I also find bugleweed to be more effective than LDN. And if someone has an elevated resting heart rate due to high thyroid hormone levels, then it’s important to get the thyroid hormone levels down as soon as possible.
Another reason why I don’t commonly recommend LDN to my patients is because it can be challenging to get a prescription. Unfortunately most endocrinologists aren’t open to prescribing LDN, and many aren’t even aware of the benefits regarding its immune-modulating effects. However, recently I’ve had a few patients get a prescription remotely by working with a medical doctor online at www.ldndoctor.com [8]. The way this works is that you schedule a consultation with a medical doctor, and they will write a 6-month prescription for LDN. I must warn you that I don’t personally know any of the LDN-prescribing doctors, although so far the feedback from my patients have been positive.
Another website to check out is www.ldnscience.org [9], where you can find a local doctor who prescribes LDN. The upside is that you not only can search for a doctor who prescribes LDN in the United States, but in other countries too. The downside is that there are some locations that don’t have an LDN-prescribing doctor. For example, I live right outside of Charlotte NC, but as of writing this blog post, the closest doctor who prescribes LDN practices approximately 2 hours away. However, if I was facing either radioactive iodine or thyroid surgery I would gladly drive a few hours to get a prescription for LDN, although I also would consider scheduling a consultation with someone through www.ldndoctor.com.
Which Option Should YOU Choose?
If you had a negative reaction to Methimazole and are currently facing a situation where your endocrinologist is pressuring you to receive radioactive iodine or thyroid surgery, you might be wondering which of these three alternatives to consider. It’s not an easy decision to make, as while I listed PTU first, this doesn’t mean that you can’t try a natural approach such as bugleweed. And even though I gave a few reasons why I don’t initially recommend LDN to my patients with Graves’ disease, you might decide to start with this option.
One of the benefits of LDN is that unlike antithyroid medication and herbs, LDN actually modulates the immune system. However, even if LDN effectively modulates your immune system, keep in mind that it’s not addressing the underlying cause of the problem. Of course neither is antithyroid medication or bugleweed, and so regardless of which of these three options you choose, you would still want to address the cause of your condition. If someone has a non-autoimmune hyperthyroid condition, such as toxic multinodular goiter, then they will want to consider the first two options I mentioned.
In summary, many people with hyperthyroid conditions take Methimazole to manage the hyperthyroid symptoms. However, not everyone with hyperthyroidism can take Methimazole, as some people experience side effects. When this is the case you might want to look into other options, including PTU, bugleweed, and low dose naltrexone.