Overactive thyroid 


Overactive thyroid gland

An endocrinologist explains what causes an overactive thyroid gland, leading to over-production of thyroid hormones, and the variety of treatment options.

Media last reviewed: 20/02/2013

Next review due: 20/02/2015

Unexpected weight loss

The most common reasons for sudden weight loss, and when to see your GP

Overactive thyroid (also known as hyperthyroidism) is a relatively common hormonal condition that occurs when there is too much thyroid hormone in the body.

Excess levels of thyroid hormones can then speed up the body’s metabolism, triggering a range of symptoms, such as:

  • nervousness and anxiety
  • hyperactivity – where a person can’t stay still and is full of nervous energy
  • unexplained or unplanned weight loss 
  • swelling of the thyroid gland, which causes a noticeable lump, known as a goitre, to form in the throat

The severity, frequency and range of symptoms can vary from person to person.

Read more about the symptoms of an overactive thyroid gland.

What causes an overactive thyroid gland?

The thyroid gland is found in the neck. It produces hormones that are released into the bloodstream to control the body's growth and metabolism. These hormones are called thyroxine and triiodothyronine.

They affect processes such as heart rate and body temperature, and help convert food into energy to keep the body going.

In hyperthyroidism, the thyroid gland produces too much thyroxine or triiodothyronine, which speeds up the body's metabolism.

There are several possible underlying causes, the most common being Graves' disease, in which the body's immune system targets the thyroid gland and causes it to produce too much of the thyroid hormones.

Read more about the causes of an overactive thyroid gland.


An overactive thyroid usually responds well to treatment, and most people are able to control their symptoms.

The three most widely used treatments for an overactive thyroid gland are:

  • thionamides – a group of medications, including carbimazole and methimazole, that stop the thyroid gland producing too much thyroid hormone
  • radioiodine treatment – a radioactive substance called iodine that helps shrink the thyroid gland, reducing its activity (the radiation contained in iodine is a very low dose and does not pose a threat to health)
  • surgery – in a small number of cases surgery may be required to remove some or all of the thyroid gland, particularly if there is a large goitre

Beta-blockers may also sometimes be used to temporarily relieve many symptoms of an overactive thyroid gland, although it doesn't target the thyroid gland itself.

It's common for treatment to lead to the thyroid not producing enough hormones. This is known as having an underactive thyroid gland (hypothyroidism). However, an underactive thyroid is not usually serious and is easily treated.

Read more about the treatment of an overactive thyroid gland.


Around 1 in 20 people with Graves' disease will also develop symptoms affecting their eyes, such as:

  • double vision 
  • sensitivity to light (photophobia)
  • tearing (excess production of tears)

This is known as Graves' ophthalmopathy and should be seen by a doctor who specialises in treating eye conditions (an ophthalmologist).

A rarer and more serious complication is a sudden and severe flare-up of symptoms, known as a thyroid storm. A thyroid storm can be life-threatening, as it causes severe dehydration and heart problems.

Read more about the complications of an overactive thyroid gland.

Who is affected

Women are 10 times more likely to have an overactive thyroid gland than men.

It is estimated that around 1 in 50 women in England currently live with an overactive thyroid gland.

In most cases, symptoms will begin somewhere between the ages of 20 and 40, though they can start at any age, including in childhood.

An overactive thyroid gland occurs most frequently in white and Asian people, and less frequently in African-Caribbean people.

Page last reviewed: 05/08/2014

Next review due: 05/08/2016


How helpful is this page?

Average rating

Based on 327 ratings

All ratings

Add your rating


The 26 comments posted are personal views. Any information they give has not been checked and may not be accurate.

trisha66 said on 07 October 2014

I was diagnosed with overactive thyroid 18 months ago 1st time I seen endocrinology doctor was told it wont get better and to have the radioiodine treatment I refused and told him I wanted to wait. I was first on various dosage levels in this time. I seen my endocrinologist this week and my levels are all normal so he has cut me down to a minimum level dosage for 3 months then I can stop taking carbinmazole, which just goes to show it can go into remission. If I had listend to him I would of destroyed my thyroid even though I never had any side effects with illness or carbinmazole. I know it could come back again but if it does will go back on carbinmazole again

Report this content as offensive or unsuitable

Megzo said on 01 April 2014

Yesterday, I was diagnosed with this condition. Not sure what is causing it, we will find out soon enough. They say weight loss is a symptom. I have not lost or gained weight and I am not eating more or less than usual.

Report this content as offensive or unsuitable

arborist_8 said on 17 February 2014

I was diagnosed with an over active thyroid over a year and a half ago. I agree with Pedros143's view. The endocrinology consultant put me on a small dose of carbimazole for a year and then took me off. I explained that I still didn't feel right but he insisted I was ok. My bloods are showing as normal but I am still experiencing thyroid type symptoms; feeling 'wired', nervous energy etc, and exaggerated by stress at work. Having spoken to a nutritionist friend I suspect that there may be a problem with my adrenal glands, hence I am researching my health issues in further detail when I came across this article. I plan to take the advice given by getalife and also to look at how changes to my nutrition may help.

Report this content as offensive or unsuitable

flowe1234 said on 17 November 2013

I think i could be suffering from this as i am always tired especially after 3:00pm. I also get a fast heart rate when i run up stairs or simply stand up to fast. I think i suffer from anxiety as i am always worried about my health which could be explained if i have this. Most of the day mostly near the evening i will feel ill like my head is all weird and dizzy kind off and i feel like staring at anything and everything or just go to bed. I have had a blood test and am getting the results this week at some point. But was just wondering if any off you have any comments to if it could be an over active thyroid??

Report this content as offensive or unsuitable

Lea19 said on 14 September 2013

Message for Lindsay Claire 34. I was diagnosed with Graves' disease several years back. I had Graves ophthalmology (the bulging eye issue). Some research done and 1000 mg of flaxseed oil capsules recommended. I tried them - one per day - and that together with my medication to reduce overactive thyroid to normal has helped. Eye back to normal for the moment. Still feels a bit uncomfortable from time to time but bulging, dryness and slight double vision has gone. Have a look at Svetla Bankova who has produced a booklet online for download called Life Manual Graves & Hyperthyroid. May work, may not but anything is worth a go to improve the eye issue. Good luck. Leola

Report this content as offensive or unsuitable

Lindsay Claire 34 said on 01 September 2013

I had overactive thyroid in 1996 I've never really understood what it was I had surgery when I was 16 and had 90% removed. I'm 34 now and have been taking thyroxine 200mg since surgery. During the last few months I've started to feel tired more and suffering with breathing problems sometimes feel like I can't get a breath I'm booking into my doctors tomorrow. There has been one thing that I've had to live with and that's my eye due to how overactive my thyroid was my eye pushed out I can never have family photos as it really shows on pictures how bad my eye is my right eye is bigger than my left and sticks out more as anybody else had the problem with there eye? Is there anything out there to correct it for example surgery.

Report this content as offensive or unsuitable

getalife said on 30 March 2013

When I was diagnosed with hyperthyroidism at age 52, 3 different consultants told me that I was too old to recover and that I should have the radioactive iodine treatment which, once the thyroid fails through overwork, leaves you taking thyroid hormone for the rest of your life.

What amazed me was that there was no attempt to find out how I'd wound up with a hyperactive thyroid (which obviously would be the first step in trying to reverse it). Having made the diagnosis they were completely disinterested and treated my questions as an inconvenience.

There was 1 almighty clue, which was that I got off a plane in Shanghai and found myself shaking. On my return I got the diagnosis. After reading extensively and not feeling any wiser, bodyclock sprang into my mind (the body needs a day for each hour difference to readjust when you cross time zones). I had a bad habit of working into the early hours (found it easier to concentrate when doing creative work). So it wasn't rocket science to think that the long flight had taken my, presumably, previously under pressure thyroid over the edge. I'd also stopped smoking a year earlier and I have a strong feeling that stopping (not that I'm advocating smoking - still worth stopping) meant that I'd withdrawn a stimulus that tricked the thyroid into thinking that my late working was fine.. Carbimazole had brought my thyroid back into the normal range but the consultants were certain that the hyperactivity would return if I stopped taking it. I stopped taking carbimazole and I stopped working late and slept whenever I felt tired. I'd sleep 2-4 hours in the afternoon. Slowly the afternoon sleepiness largely disappeared. Its now been almost 3 years and I have remained in the normal range. I do occasionally get overactive thyroid type symptoms which reminds me not to revert to old habits.

My advice - read all you can, try and figure what the cause might be and, if you think it might be this or that, reverse the behaviour.

Report this content as offensive or unsuitable

didcotsue said on 20 March 2013

I have an overactive thyroid and was diagnosed with it the second time in 2010 am on Carbimazole and am waiting to have an assessment for having thyroid removed,

Report this content as offensive or unsuitable

hannah1066 said on 24 February 2013

Hi im 46 and only just been diagnosed with underactive thyriod, havent started taking anything yet, in the last 9 months I have lost 2 and a half stone at slimming world i feel better than I have done in years, I had a blood test for something else and this is when they told me. I am now completely freaked out after reading some of your comments as I dont have any of the symptoms listed and Im now worried about taking pills when I feel so well. Not sure what to do?

Report this content as offensive or unsuitable

Shelly50 said on 01 November 2012

This is the third time in ten years my thyroid has gone overactive. I was on Carbimazole again but it has played havoc with my white cell count so switched on to the alternative drug propylthiouracil to see if that is OK with my white cell count had a blood test today get results next week and will be going to the hospital and my GP for results. Think my thyroid is underactive now because I am putting on weight. I hate this part when you are use to be being so thin the last time I ended up having to buy new clothes because I went up a clothes size hope that doesn't happen this time. Really fed up it has come back and I dont always recognise it this time my legs went weak walking up hills and I saw my GP who thought it was my thyroid I've said to the specialist this time I would prefer a regular blood test when I come off the drugs to check my levels rather than just discharging me and hoping it doens't come back.

Report this content as offensive or unsuitable

danni89 said on 05 August 2012

Hi, two and half years ago i was diagnosed with over-active thyroid. kept getting blood checked for it and it never showed.i had all the symptoms for two years prior was constantly at the doctors who kept palming me off in my terms he thot i was a nut case, it got to a bad stage where my heart was hitting over 130bpm before the looked into. two days after bloods i was confirmed. i have had 2 year treatment on carbimazole stopped in October 11 one month later all symptoms back and no treatment as doctor wont give me treatment till blood levels show yet there near there but keep fluctuating. hope it shows soon symptoms are back meaning bigger trouble . carbimazole is available as generic not as neo-mercazole i work in pharmacy in N.Ireland

Report this content as offensive or unsuitable

TD888 said on 15 July 2012

Hi, i think i may have this. In 2010 i suddenly started feeling unwell, i put it down having a bug, but the bug never got better. It took me ages to manage to find the courage to ask a GP's help. I ended up with a diagnosis of an anxiety disorder. I was coping with it until i read about this and realised that Hyperactivity and my heat phobia could be symptoms not just little quirks. Next week (It's Sunday now) I'm going to go and badger my GP for a blood test, to rule this out. I can't continue with therapy for anxiety if the anxiety is caused by an over-active thyroid.

One slight problem, i'm an 18 year old male which makes them less likely to want to believe that it could be hyperthyroidism. But it has to be something, this anxiety, these symptoms are not me, i have never been so boring and i am well and truly sick of feeling so rubbish all the time, i can't go out without this irrational fear making me feel sick, i can't go on holiday, i can just about manage a day out with friends. But this is not normal, and i have difficulty believing that this is mental.

Anxiety is manageable. Never thought i'd say it, but fingers crossed i have hyperthyroidism, because it's treatable, and my symptoms fit. I'll update when i get results, even if it's to complain about my GP.

Sad to see a lot of GP's not listening to patients, i really feel for you, and i hope that i do not suffer the same problems!

Report this content as offensive or unsuitable

katy1967 said on 07 July 2012

hi streetka2012
i've just been diagnosed this monday in fact. I was prescribed Carbimazole, the chemist gave me 63 out of 100 and said she didn't think she would be able to get any more, didnt realise that they had been discontinued. I did mention to my doctor who said not to worry there are alternatives
Why can't your doctor prescribe something else? Have they sorted anything out for you?

Report this content as offensive or unsuitable

streetka2012 said on 28 June 2012

Can anyone shed any light as to why Carbimazole has been discontinued, my GP cannot prescribe an alternative, and after taking it for only 2 months I am without anything until my hospital appointment in 2 weeks,

Report this content as offensive or unsuitable

User660196 said on 27 March 2012

I have just been diagonsed as having an overactive thyroid with symptoms of extreme tiredness, piling on loads of weight and muscle weakness, so went to g.p and after a few years of being told i was depressed when i knew i wasnt, he checked my thyroid but only after the weight gain, expected the results to come back as having an underactive thyroid so i was extremely suprised when it came back overactive, so i am now taking carbimozole and hoping i am not going to put an more weight on.

Report this content as offensive or unsuitable

dUb Samurai said on 06 February 2012

Hi I am a 19 year old male and have been severly underweight my whole life. I weigh 8 and a half stone which is less than I weighed 5 years ago. I'm always eating, have very irregular sleep and have pretty much no muscle. I feel tired all the time and get really anxious for no reason. My heart is always going a mile a minute whatever I'm doing and have horrible anxiety. I haven't been to the doctor's but was wondering how this compared to other people's experiences with this disorder.

Report this content as offensive or unsuitable

smergyl said on 10 August 2011

I have been recently diagnosed with an overactive thyroid and have been given carbimazole and bisoprolol to regulate it. Sadly in the past an ignorant doctor has not seen the signs and has diagnosed me with the eating disorder Anorexia. I now have to take my husband with me to doctors appointments so he can verify I do eat quite a bit and am not starving myself. I eat around 2500 cals a day and still have a bmi of 16, it has stayed steady for some time and doesn't fluctuated that much. I am hoping the tablets will fix this as I'm sick of the way I get treated when I go to the docs for something and get tons of abuse for my weight.

Report this content as offensive or unsuitable

angeleyes06 said on 20 October 2010

i found a lump in my neck and went to see my doctor who then reffered me for blood tests and scans. i had a complete thyroidectomy in september 2009 and im now on 175mg thyroxine and i feel so much better, no more palpatations or anxiety attacks. i also have bloodtests done every 3 months. if you feel the symptoms returning yourself you can request a bloodtest to have your levels checked.

Report this content as offensive or unsuitable

Taylor1980 said on 29 September 2010

My symptoms started when I was 15. Lost loads of weight whilst eating like a horse. It was my optician who diagnosed it as he noticed my eye's starting to bulge. I was sent to the hospital and diagnosed with overactive thyroid and thyroid eye disease. I was on carbimizole for ages but it did nothing. I had 90% of my thyroid removed aged 16, which then left me underactive and on thyroxine for the rest of my life.Had radiotherapy to try and shrink my eye musle but that didn't work. I had eye surgery aged 18 to remove some of the bone from my eye sockets, which sorted them out at last (except for another surgery to correct my eye musles). Since then I have been well controlled on 200mg of thyroxine daily. I did get type 1 diabetes when I was 18, but I'm not sure if this is linked to my thyroid problems. I had my first child in 2007, 5 weeks early, 5lb 6oz , and had to stay in hosp for 12 days as he had a few problems, but is now a normal, happy 3 year old. My medics have been great considering, my doctor has told me I'm her only patient with this condition. This week however I have been having problems with my heart racing and generally feeling tired. Awaiting my blood test results but my doctor thinks it may have gone overactive again, even though I only have 10% left. Has anyone else had a reaccurance like this?

Report this content as offensive or unsuitable

ashley gordon said on 11 September 2010

Hi im 13 years old and i went to my GP because i couldnt lose any weight and just kept gaining it and i can sleep all day and night if i could. My family thought there was something wrong with me as i just gained weight and couldnt lose it.
I hated been like this so i went to my doctor and had my blood taken.
Then my mam got a phone call from my doctor saying my blood tests had came back, so we went down and got referred to hospital staight away with a very bad under active thyroid. They took my blood and done what they had to do and after a while gave me some tablets.
Im on 75mg at the minute but i wish the doctors would just put me up faster its taking ages and im not on my steady amount as i need to be put on a high amount.
I have lost a bit of weight as i go to the gym. But other then that i havnt changed a bit.
but hopefully i will when im on my full amount .

Report this content as offensive or unsuitable

bigthroat80 said on 17 August 2010

I went to my gp with a goitre and feeling rough. GP referred me straight away. Saw a consultant within 3 weeks. Diagnosed with graves. All the medical professional have been great. And more importantly made me feel better.

Report this content as offensive or unsuitable

molden said on 31 July 2010

it is seven and a half years since i started with symptoms.one and a half years were spent spent telling a so called doctor of these symtoms. they just kept nodding like a noddey dog and smiling.By chance went to another doctor and was diagnoised right away.I have just lived through the worst seven and a half years of my life all because a doctor who is being paid a lot of tax payers money can not do the job they are being paid to do. I have had one eye opperation and will have to have another. Why are so many so called doctors allowed to get away with not being competent. They are costing the NHS a fortune.I think it is about time we charged them their mistakes then we would start getting a decent standard of doctors in our health centers and cut down on the so called waste in the NHS.

Report this content as offensive or unsuitable

sirmdolan said on 23 July 2010

i have had symptoms for well over four months and initially thought i had throat cancer so i was extremely concerned about my condition i saw one doctor who basically fobbed me off as though i was some sort of hypochondriac and sent me away i saw a different doctor on the second occasion who i was equally unimpressed with although he did make me an appointment to see an ENT specialist which i attended only to be sent home again by a professional who was also flummoxed and could shed no light on my condition!, During this time it came to light to my doctors receptionist that i had moved house and was no longer in the catchment area so i was to to find another doctors practice ASAP as they would no longer see me any more. I promptly to their advice and found myself a new practice on monday this week 19/7/2010 i went to see my new doctor with the same symptoms blood was taken and i was sent to the hospital for an x-ray, on tuesday i received a phone call from the doctors receptionist asking me to make an appointment as my blood test results were back and the doctor wished to discuss them with me , on wednesday i returned to the doctor and was informed that i had an over-active thyroid .

Report this content as offensive or unsuitable

Sickly said on 23 June 2010

The first comment sounds very much like my own experience. In my case the GP did find a large nodule on my thyroid, it was scanned and rescanned, beyond that nothing.

I have now identified for myself symptoms over over production of thyroxine.

I plan to see the GP again - but will they do anything ?

Report this content as offensive or unsuitable

Pedros143 said on 19 April 2010

Thyroid GP treatment seems to be a case of " identify and forget", (identifying usually done by the patient.) There appears no real follow up or concern on having regular blood tests or symptom checking for the patient once this is confirmed. Very little information is given to the patient about the downside of levothryoxine, so any after effects come as a surprise only to the patient, who then has to make another appointment to find out about them. Pretty poor show all round on this specific disease management.

Report this content as offensive or unsuitable

User80252 said on 26 March 2010

i had a subtotal thyroidectomy in 1990 for an hyperthroidyism and was not given any medication. Over the past few years i have felt symptoms return.

Report this content as offensive or unsuitable

Women's health 18-39

Healthy living advice for women aged 18-39 including real stories, fitness, diet, fertility and sexual health

Symptom checker

If you have a health problem, our symptom checker can help you manage it or find out where to go for help

Follow us on Twitter

Join more than 150,000 who follow @NHSChoices for the latest and best health news and lifestyle advice