Overactive thyroid treatment: when it’s needed and what to expect

29th May, 2022 • 12 min read

Your thyroid gland is a small gland in the front of your neck. It may be little, but it’s very important – it makes hormones that help control your metabolism, keeping you warm and helping your organs work normally. So if you have a thyroid problem, it can affect how your body works and have a big impact on your day-to-day life.

Perhaps you’ve noticed changes to how you look, such as weight loss or hair thinning, which has knocked your mood and confidence. Or maybe you’re dealing with feelings of nervousness, or you’re exhausted due to lack of sleep? If so, you could have an

overactive thyroid (hyperthyroidism)
– when your thyroid gland makes more hormones than your body needs.

Women are more likely to get thyroid problems – according to the American Thyroid Association, about 1 in 8 women will be affected at some point. And if you have a hectic life, what with working all hours, maybe also looking after children and/or caring for older relatives, you may put your health low on your to-do list. But remember that it's important to look after yourself, too.

The good news is that, like other thyroid problems, an overactive thyroid can be effectively managed, so it’s important to see your doctor for a diagnosis. There are

self-care measures to help ease your symptoms
, as well as a few things to bear in mind about your diet – but an overactive thyroid needs medical treatment. So read on to find out what the options are, when they might be used, and how they work.

Overactive thyroid medication

If you’re diagnosed with an overactive thyroid, you’ll usually see a specialist, who will be likely to recommend anti-thyroid medicines called thionamides as a first line of treatment. (In some cases, they can also be prescribed by your family doctor.)

These medicines work by reducing the amount of thyroid hormone your thyroid gland releases into your body. They’re used either for a short time to prepare you for other treatments (see below), or in the longer term if you have

Graves’ disease
– the most common cause of an overactive thyroid, which can sometimes be cured with medication.

Here’s what you need to know:

The medication can take time to work

  • anti-thyroid medicines usually take about 6 to 8 weeks to stop your thyroid gland being overactive
  • you may also be given
    beta blockers
    to help ease some of your symptoms(thyroid-over-active#overactive-thyroid-signs-and-symptoms) in the meantime – these block the effects of the hormones, rather than stopping your thyroid gland making them

You’ll have regular check-ups and your dose may be adjusted

  • your doctor will see you a few weeks after you start taking anti-thyroids, to see how you’re feeling and do a
    thyroid function blood test
    to check your hormone levels
  • if things are improving, your medication may be adjusted
  • in some cases, your dose will be reduced, with the aim of finding the lowest amount you need to keep your thyroid gland working normally
  • in other cases, you’ll need to continue your anti-thyroid medication and also take a medicine called levothyroxine, to replace the thyroid hormone you’re not making – known as ‘block and replace’ treatment
  • you’ll usually take medication for up to 18 months, then have regular blood tests and check-ups over the next 6 to 12 months to see if your thyroid becomes overactive again – known as a ‘relapse’

Your longer term plan will be individual to you

  • if your blood tests are normal 12 months after stopping medication, you won’t usually need more treatment, and will just have an occasional thyroid blood test
  • in some cases you’ll need to take medication for longer, or even for the rest of your life
  • you should see your doctor if your symptoms come back at any point

Side effects to watch out for

Like any medication, anti-thyroid medicines can cause side effects. These are usually mild and happen in the first month or 2 of treatment.


itchy rash
is the most common side effect, affecting about 5 out of every 100 people (meaning 95 in 100 people won’t get it).

What you can do: Talk to your doctor, as they may be able to recommend an alternative medicine (the rash will go away when you stop taking the medication).

Other side effects can include:

  • changes to your sense of taste
  • feeling sick (nausea)
  • headaches
  • fever
  • aching joints

What you can do: These will usually settle down as your body gets used to the medicine – but speak to your doctor if you’re worried.

In extremely rare cases, anti-thyroid medications can cause a serious side effect called agranulocytosis, where there’s a sudden drop in your white blood cells. This can make you very vulnerable to infections, and is potentially life-threatening.

What you can do: If you’ve started anti-thyroid medication in the last 3 months and you get symptoms such as a high temperature (fever) or sore throat, you should stop taking your medication and see your doctor right away – or go to your nearest emergency department.

Find useful information on other areas of thyroid health with our

complete Guide

Radioactive iodine treatment

This is a type of

treatment that stops your thyroid gland from making too many hormones. It may be used if:

  • anti-thyroid medication isn’t effective or isn’t suitable for you
  • your symptoms come back after you stop taking anti-thyroid medication
  • you would prefer to have this treatment rather than taking medication

Here’s what you need to know:

It’s very effective, but can take a while to work

  • you’ll usually only need 1 treatment to stop your thyroid from being overactive
  • it can take a few weeks or months to see the full benefits, so you may need to take anti-thyroid medication in the first few weeks after treatment

It uses low-dose radiation

  • you’re given a drink or capsule to take, which contains iodine and a low dose of radiation, which is then absorbed by your thyroid gland
  • this destroys cells in your thyroid gland, to reduce the amount of hormones it can make
  • although the dose of radiation is very small, you should avoid spending time with children and pregnant women for a few days or weeks afterwards

It isn’t suitable for everyone

  • you shouldn’t have it if you’re
    or breastfeeding, or if your overactive thyroid is causing severe eye problems
  • you should also avoid getting pregnant for at least 6 months afterwards (or avoid getting someone else pregnant for at least 4 months)

Side effects to watch out for

After the treatment, your thyroid gland may be slightly tender, but this usually clears up within a few days. There’s no risk of losing your hair from this type of radiotherapy.

A common longer-term side effect is an

underactive thyroid (hypothyroidism)
– when your thyroid gland doesn’t make enough hormones. This is thought to affect about 1 in 3 people (so 2 in 3 people won’t get it).

What you can do: Work with your doctors. You’ll need regular thyroid blood tests from 4 to 6 weeks after treatment, so you can be treated with hormone replacement medication if necessary (read more about

underactive thyroid treatment


In some cases, you’ll need surgery to remove some or all of your thyroid gland. This may be if:

  • you have an enlarged thyroid gland that’s causing breathing or swallowing problems, or severe eye problems
  • you can’t have the treatments mentioned above
  • your symptoms come back after trying other treatments

How much of your thyroid gland needs to be removed will depend on what’s causing your condition. The aim is to remove enough to relieve your symptoms, while still allowing your gland to make the hormones you need.

Options include removing:

  • all your thyroid gland – total thyroidectomy
  • half your thyroid gland – lobectomy or hemithyroidectomy
  • most of your thyroid gland, leaving a little tissue on 1 side – near-total thyroidectomy
  • the central part of your thyroid gland – isthmusectomy (rarely performed)
    In some cases – such as if your whole gland is removed – you’ll need to take hormone replacement medication for the rest of your life.

Side effects to watch out for

Complications from thyroid surgery are thought to happen in about 1 to 2 out of every 100 operations (so they don’t happen in 98 to 99 out of 100 operations).

The main possible complications include:

  • infection – usually treated with antibiotics
  • nerve damage – which can lead to a permanent hoarse voice
  • damage to you parathyroid glands – these tiny glands behind your thyroid regulate your calcium levels, so you may need to take calcium supplements for life

Diet and overactive thyroid

Can your diet play a part in managing your overactive thyroid? Here's what you need to know.

There isn’t an ‘overactive thyroid diet’

Despite what you may have read or heard, medication is still the main treatment for overactive thyroid. There are no foods that will treat it, and there isn’t a particular diet you should follow.

The best thing you can do is make sure you’re eating a

healthy, balanced diet
that contains all the nutrients your body needs to work at its best. Eating well and taking regular exercise can also help you keep your mood and energy levels steady – which can be challenging when you have an overactive thyroid. (Read more about
healthy eating

If you’re worried that you’ve lost weight because of your overactive thyroid, read our advice on

managing your weight with a thyroid problem
– including tips on how to gain weight safely.

Avoid too much iodine

is used by your body to make thyroid hormones. But if you have an overactive thyroid, excessive amounts of iodine can make your symptoms worse and interfere with your anti-thyroid medication.

While you don’t usually need to follow a low-iodine diet, you should avoid foods that contain very high levels of iodine – such as kelp or some seaweeds – and iodine supplements.

Try cutting out caffeine

Feeling restless, nervous or anxious and having trouble sleeping are common symptoms of an overactive thyroid. And in some people, caffeine can make these symptoms worse.

If this is you, it might be worth avoiding or limiting caffeine – think coffee, tea, chocolate and cola – while you’re waiting for your thyroid medication to work, to see if this helps your symptoms.

Keep an eye on calcium and vitamin D

When you have an overactive thyroid, having too much thyroid hormone can lead to increased bone loss. Over time, this can increase your risk of weak bones (


Once your overactive thyroid is being treated, your rate of bone loss will slow down, and your bones may get stronger again. But making sure you’re getting enough calcium and vitamin D can also help prevent osteoporosis, as both are essential for bone health.

Most people can get the calcium they need by eating a balanced diet that includes dairy foods such as milk, cheese and yoghurt (read more about good sources of calcium). Vitamin D is made in your skin when it’s exposed to sun, and can also be found in oily fish such as salmon, and eggs (read more about getting

enough vitamin D

If you’re worried you’re not getting enough calcium or vitamin D, speak to your doctor about whether you should take a supplement.

When to see a doctor

Getting a diagnosis

You should always see your doctor if you think you have

symptoms of an overactive thyroid
or another thyroid problem.

They’ll be able to refer you for thyroid function tests and scans to make a diagnosis and help you get the right treatment.

Remember that many of the symptoms of thyroid problems can also be caused by other conditions. If you’re worried about any symptoms and not sure if you need to see a doctor, try our

Smart Symptom Checker
to get advice on your best next step.

Getting urgent care

You should get urgent medical attention or go to your nearest emergency department if you:

  • have trouble breathing or swallowing
  • can’t fully close your eyes
  • have
    heart palpitations
    that won't go away or keep coming back
  • have trouble moving your arms or legs
  • are taking anti-thyroid medication and get a sore throat,
    mouth ulcers
    or an unexplained fever – as explained above, these may be signs of agranulocytosis
  • have a fever, fast heart rate, agitation, yellowing of the skin or eyes (
    , or feel faint or black out – these can be signs of a ‘thyroid storm’, a rare complication of an overactive thyroid that can be triggered by surgery, infection, pregnancy or suddenly stopping anti-thyroid medication

Doctor’s tip

“Eye problems are quite common with an overactive thyroid,” says Dr Roger Hendseron, “with possible symptoms including dryness, watering, sensitivity to light, blurred vision, swollen eyelids or bulging. Once you start treatment, these symptoms usually begin to settle, and in many cases they’re only mild. But in every 20 to 30 cases, there’s a risk that your eyesight may be damaged. So if you have an overactive thyroid and notice any eye problems, always tell your doctor – you may need treatment, such as eye drops or steroids.”

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.