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Popular Brands: : Methimazole, Tapazole, Mercazole, Methizol, Thyrozol
Official FDA Reports11,168
Social Media Events544
Total Posts409
Avg. Review Score3.45/ 5
Active Ingredients
  • Methimazole
  • King Pharmaceuticals Inc
  • Mylan Pharmaceuticals Inc

  This report is for all products sharing this active ingredient. For more details, please use our Workbench for research on individual brands like Methimazole.

* Extracted from FDA Adverse Event Report


The quarterly trend chart illustrates changing levels of adverse events over time. Results from both the FDA Adverse Event Database (FAERS) and adverse events extracted from social media by Druginformer are plotted side-by-side for easy comparison.

The proportion of people completing user reviews who complained about a side effect.

The proportion of social media adverse event complaints for each adverse event type.

The proportion of FAERS (FDA) adverse event complaints for each adverse event type.

Methimazole Side Effects

  Social Media
(Online Comments)
(Reports Submitted to FDA)
Side Effect On Drug
Reports % of
Alarm Reports % of

* DrugInformer calculates alarm using a proprietary algorithm. Alarm should not be taken as an ofiicial signal from the FDA or other regulatory entity.

User Voices

The following are comments from users that experienced side effects while taking Methimazole


Early in treatment Drs. would give me a specific dose to take for as long as 6 weeks. During this amount of time, on say..30-20 mgs per day, my thyroid would become so enlarged, I could ...

Source: Methimazole

View full report on Methimazole related thyroiditis

Did the author experience thyroiditis while taking methimazole?

What is this?


... I now have a better handle on it.. and monitor my self with either breaking pills or smaller doses which I can control. ALSO--I now have Osteopenia . Stabilizes my thyroid functio...

Source: Methimazole

View full report on Methimazole related osteopenia

Did the author experience osteopenia while taking methimazole?

What is this?


... that were haunting, and devistated my life in many areas. Am drinking fluids, one of my side effects of the hyperthyroid was not being able to eat or hold down food, but very hungry all the time. I am...

Source: Methimazole

View full report on Methimazole related hunger

Did the author experience hunger while taking methimazole?

What is this?

Tell us about your Experience with Methimazole

Thank you for sharing your experience with us!

Share Your Experience

Druginformer Identified Side Effects: Abdominal pain upper, Burn oesophageal, Abdominal discomfort

Effectiveness Rating:     Overall Rating:

Posted By Rose on November 11, 2016 @ 2:23 pm

I am a tennis teacher, I never smoked,drink I have a healthy life.the pain starts first after Methimazole started. My endocrinologist stopped my medication. The pain was worse after 7-8 pm, end ends after 4-5 hours.

Druginformer Identified Side Effects: Abnormal weight gain, Weight increased

Posted By Charlene Lee in fdb.rxlist.com on October 27, 2015 @ 12:00 am

... to maintain or lose weight. A few weeks of this "medication" and I had gained 35 lbs. I continue to gain even though I'm off of it. Even at 600 calories per day, I still gain weight. Have a lot more ...

Druginformer Identified Side Effects: Fatigue, Alopecia, Insomnia, Vision blurred, Weight increased, Congenital skin disorder

Posted By Holly in fdb.rxlist.com on July 19, 2015 @ 12:00 am

Hair loss, weight gain, sleeplessness,blurry vision, skin problems, constantly tired. Dr. just continues to tell me that my levels are good and no reason to change anything. Looking for a natural heal...

Druginformer Identified Side Effects: Thyroiditis, Rash

Posted By Anonymous in fdb.rxlist.com on June 30, 2015 @ 12:00 am

I have been on methimazole for three years and broken in out in a full body rash three times. My thyroid function is still slightly high, but I am finally going into remission.

Druginformer Identified Side Effects: None

Posted By Bobbe in fdb.rxlist.com on April 26, 2015 @ 12:00 am

Druginformer Identified Side Effects: None

Posted By Anonymous in askapatient.com on January 13, 2015 @ 12:00 am

Side Effects: None Successfully lowered my thyroid hormone production. Unfortunately, i still felt on verge every day all day, so I was prescribbed low dose of propranolol which took care ...

Druginformer Identified Side Effects: None

Posted By Anonymous in fdb.rxlist.com on September 18, 2014 @ 12:00 am

I was diagnosed with a hyperthyroid a year ago. I was put on methimazole, and my blood levels are now within a normal range. I have had no side effects at all.

Druginformer Identified Side Effects: Decreased activity, Bronchitis

Posted By Moudsie in fdb.rxlist.com on September 12, 2014 @ 12:00 am

I, against my better judgement, and at the md's urging, took one freaking pill--5 mgs. this AM (a year ago I was diagnosed with underactive thyroid--put on meds--lost 31 pounds (to 86) got bad bronchi...

Druginformer Identified Side Effects: Urticaria, Thyroiditis

Posted By DivaYv in fdb.rxlist.com on September 7, 2014 @ 12:00 am

I was prescribed Methaimazole 10 mg 3 X day for an overactive Thyroid. I took the medication for exactly two weeks and broke out in Hives. I stopped the medication and I plan to visit the endocrinolog...

Druginformer Identified Side Effects: None

Posted By Anonymous in fdb.rxlist.com on July 12, 2014 @ 12:00 am

Additional Drug Information

* Warning: The facts and figures contained in these reports are accurate to the best of our capability; however, our metrics are only meant to augment your medical knowledge, and should never be used as the sole basis for selecting a new medication. As with any medical decision, be sure to work with your doctor to ensure the best choices are made for your condition.

* About FAERS: The FDA Adverse Event Reporting System (FAERS) is used by FDA for activities such as looking for new safety concerns that might be related to a marketed product, evaluating a manufacturer's compliance to reporting regulations and responding to outside requests for information. Reporting of adverse events is a voluntary process, and not every report is sent to FDA and entered into FAERS. The FAERS database may contain duplicate reports, the report quality is variable, and many factors may influence reporting (e.g., media attention, length of time a drug is marketed, market share). For these reasons, FAERS case reports cannot be used to calculate incidence or estimates of risk for a particular product or compare risks between products.