Methimazole and Heart Palpitations: What Users Say

• 123...
• Taken for 5 to 10 years
• February 7, 2020

For Hyperthyroidism "When I was diagnosed with hyperthyroidism, I believe this drug methimazole saved my life. I was having anxiety attacks, heart palpitations like crazy, and I thought I was literally going out of my mind. I would wake up with incredibly high heart rates, thinking I was having an anxiety attack before I found out I had hyperthyroidism. I would even sometimes hallucinate to a certain extent. Drinking alcohol was the only thing that helped me. I started off at 20 mg a day and, to be honest, I cannot remember any bad side effects except for after about a month, I started feeling a whole lot better and felt like I had my life back. After a couple of years, I have reduced it down to 2.5 mg a day, which is where I am now. I have tried to lower my dose, but it seems to get worse each time I do so. 2.5mg seems to be my sweet spot. Anyway, there seems to be a lot of negative comments on here so I guess I'm one of the lucky ones when it comes to the side effects."

• Ang...
• Taken for 1 to 6 months
• April 10, 2018

For Hyperthyroidism "I honestly believe methimazole saved my life. No more night sweats, no more insomnia (3-4 days at a time with no sleep at all), no more heart palpitations, no more anxiety, not more thinking I was losing my mind. No longer do I take propranolol for heart palpitations. After 3 years of struggling with hyperthyroidism, I’m finally back to my normal self. I’ve got my life back thanks to methimazole."

• Bro...
• Taken for 1 to 6 months
• January 9, 2021

For Hyperthyroidism "I was diagnosed with hyperthyroidism in August 2020 and was put on 20 mg of methimazole. Within 1.5 weeks, I gained a whopping 10 lbs. My doctor reduced my dosage to 10 mg, and my weight, heart palpitations, and sleepless nights slowly went away. I'm still having dry eyes, a little eye bulging in one eye accompanied by it being wider than the other, and blurred vision that I’m seeing an ophthalmologist for now. Now I'm dealing with little red bumps and the feeling like something is always biting me. I always think a bug is crawling on me, and I am itching all the time. I scratch so much that I actually end up with tiny sores, mostly on my arms. I just did my blood work on January 5, 2021, and was informed today that my levels are still low. I'm going to a new endocrinologist next week to see if we can get this under control ASAP. I’m tired of it all and I’m tired of going to so many doctors all the time. I want my life back!!!!"

• Kat...
• Taken for 1 to 2 years
• July 9, 2021

For Hyperthyroidism "I had Graves' disease 25 years ago, and now again. This time, heart palpitations, shaking, hot all the time, lost 18 lbs in one month, sleepless nights. Started on 5 mg methimazole once a day. Immediately I started feeling better. I had hair loss, weight gain, depression, fatigue, and muscle pain. I have been on it for just over 1 year. For the past 4 months, my T3 and T4 have been normal, however, my TSH has dropped to 0.05. When I was taking 2.5 mg, my TSH was 0.30. I have now developed an eczema-type rash on 1 elbow, 1 knee, and on my toe. I think it is too much methimazole, but the doctor feels differently. I am supposed to be taking 5 mg, however, I am only taking 2.5 mg and have noticed my skin getting better. I am also a smoker, and I have found out that smoking can cause Graves' disease. 25 years ago, I was on methimazole for 8 months and quit smoking, Graves went into remission. Trying to quit again. Good luck to all with this disease."

• RoG...
• November 15, 2020

For Hyperthyroidism "1st diagnosed with hyperthyroidism, Graves' disease in 2016. Symptoms were mild, occasional palpitations, weight loss, felt hungry, anxiety, warm, headaches. Endocrinologist started on 10 mg. Immediately gained weight, but since heart palpitations were occurring, was advised to work out less. Also noticed leg, back muscle pain, fatigue, itchy skin. Lowered dose to 5 mg 6 months later. Changed to new endocrinologist in 2017, dosage lowered to 2.5 mg daily. My weight back to normal, had no symptoms, but my TSH was low, often less than 0.5. Then in 2018, lowered to 2.5 mg every other day. In 2019, was advised to stop taking it. TSH was at 1.5-2.5. In April 2020, I started to feel heart palpitations, weight loss again, consistently felt through summer. Was put back on 5 mg daily, TSH 0.01. Been back on for 3 months, did gain weight, but not drastic like before. Felt itching again. I hope my test results in 2 months will allow me to lower the dose again or stop."

• Stu...
• Taken for less than 1 month
• February 17, 2020

For Hyperthyroidism "I am a type 1 diabetic for 40 years and was just diagnosed with mild Graves after a radioactive iodine uptake scan. My free T4 is 2.01, TSH is .02, 6-hour scan was 17, but 24-hour was 37. My endo just prescribed this at 5 mg/day. After reading the reviews, I was scared to try the medication; however, the anxiety and palpitations are bad, so I’ll give it a shot. If this doesn’t help, I’ll ask for beta blockers until RAI therapy."

• sur...
• Taken for 1 to 6 months
• January 26, 2021

Methimazole for Hyperthyroidism "Third update, been on Tapazole for 6 months, initially 3 pills, then the last 2 months 1 pill. A week ago I got a skin rash on my arm, the doctor told me to stop the med for 1 week until the rash gets better and he will prescribe me something else. Today I got called by the endo and told to do a blood test to check levels again. I got a call from the hospital and they told me my T4 went from 25 to 100 and my T3 from 7 to 30. They asked me if I had any palpitations or any other bad effects, I said no. They told me if I feel anything, go to the ER right away. Of course, with this news, my heart went up to 135 palpitations, so I went to the ER. The doc at the ER called another endo and I got prescribed propylthiouracil and back to propranolol. I can't believe 1 week of this will take me from 25 to 100, not even when I got diagnosed with hyper it was 33 only. Appointment tomorrow with my endo, I think I'll go radioactive iodine. Too many side effects."

• Anonymous
• Taken for 2 to 5 years
• September 8, 2021

For Hyperthyroidism "I've had hyperthyroidism for 4 years and went into remission. Now it came back. I lost so much weight and was feeling so sick without medication. Truthfully, I didn't want to get fat again. The last time I gained 15 pounds, it was horrible to lose, but the pills helped it go away. Now it's back. I felt so sick I took myself to my endocrinologist, and she put me back on again. It's been 2 weeks, and I'm starting to feel better. No more stomach symptoms anymore. It sucks to gain weight, but my heart palpitations have lessened, and I'm feeling normal again."

• Reg...
• Taken for 6 months to 1 year
• July 10, 2025

For Hyperthyroidism "I was diagnosed with Graves’ disease after being in remission for 6 years. I had tachycardia, tremors, slight weight loss, nervousness, and fatigue. After 9 months of 20 mg of methimazole, the symptoms have subsided, T4 and T4 normal, but TSH is almost at 16. Side effects: hair loss (falling out in clumps), extreme fatigue, weight gain, and bloating. My dosage has been lowered to 10 mg since now I am hypothyroid instead of hyperthyroid. Radioactive iodine treatment has been discussed, but I’m not in favor of it. I hope the hair comes back and the weight comes off. I also have leukemia, so this may have affected the Graves’ disease. The medicine does its job, but the side effects are very upsetting to one’s personal appearance and emotional being."