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The iodine used for this treatment is radioactive, but it’s generally very safe for you to have. After you’ve taken radioactive iodine, most of it leaves your body in your urine. Some also leaves your body in your sweat, tears, poo and saliva. This takes a few days to a week and as time goes on, the amount of radioactive iodine in your body gets less and less.
For a short time while your body is getting rid of the radioactive iodine, you’ll be asked to take precautions to keep others safe. These include being careful about what contact you have with other people, and for how long. Your doctor will give you clear advice about what you should do. Ask questions if you’re not sure about anything.
The advice will probably include:
- limiting contact with babies, young children and pregnant women
- staying away from crowded places where you’d be close to others for a long time (for example, in cinemas)
- not sharing a bed
- instructions about washing, laundry, and preparing food for others
You’ll be told how long you need to follow the precautions in your particular circumstances.
If you’re pregnant or breastfeeding, you shouldn’t have radioactive iodine. This is because radiation can pass through the placenta and into breast milk, so it may harm your baby. Ideally, wait six months after having your treatment before you try to get pregnant. Men should wait at least four months after treatment before trying for a baby.
If you have any concerns or questions about radioiodine treatment, talk to your doctor.
If you have an overactive thyroid caused by Graves’ disease, you could develop problems with your eyes. Around a quarter of all people with Graves’ disease develop a condition called Graves’ ophthalmopathy, also known as Graves' orbitopathy or thyroid eye disease. It’s more common in people who smoke.
The main symptoms of thyroid eye disease are:
- bulging or staring eyes
- swollen and red eyelids
- watery eyes
- an aching feeling behind your eye, which gets worse in the morning and when you move your eyes
- red and irritated eyes
- sensitivity to light
- double vision, especially when you look upwards and to the side
Most people who have thyroid eye disease have mild eye problems, which may get better on their own or may need treatment. But it’s possible to develop more serious problems including ulceration of your cornea (the outer layer at the front of your eye) or even loss of sight.
So, if you have any of these symptoms it’s important to see your GP as soon as you can. Your GP may refer you to an ophthalmologist (a doctor who specialises in eye health, including eye surgery).
The type of treatment you have for thyroid eye disease depends on your symptoms and how severe they are. Treatments include eye drops, medicines (such as corticosteroids) and surgery.
If you have an overactive thyroid, it can affect your periods and your ability to get pregnant. Your periods may be shorter and happen more or less often. Or you may have no periods at all. Some thyroid conditions – for example, Graves’ disease – are also linked to conditions like endometriosis and polycystic ovary syndrome. These conditions can make getting pregnant even more difficult.
If you have problems getting pregnant, your doctor may do a blood test to measure your level of thyroid hormone. Treating any thyroid condition may help improve your chances of getting pregnant and having a healthy pregnancy.
You don’t need to follow any special diet if you have an overactive thyroid, just aim to eat healthily. After you’ve had treatment, you might want to consider what and how much you eat. For tips and advice about healthy eating and portion sizes, see our section: Related information. While your thyroid was producing too much hormone, you may have felt hungry and eaten more to keep your weight up. After your treatment, you may need to eat less to avoid putting on weight.
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This information was published by Bupa's Health Content Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals and deemed accurate on the date of review. Photos are only for illustrative purposes and do not reflect every presentation of a condition.
Any information about a treatment or procedure is generic, and does not necessarily describe that treatment or procedure as delivered by Bupa or its associated providers.
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- Graves’ disease. BMJ Best practice. bestpractice.bmj.com, last reviewed October 2020
- Toxic multinodular goitre. BMJ Best practice. bestpractice.bmj.com, last reviewed October 2020
- Hyperthyroidism and thyrotoxicosis. Medscape. emedicine.medscape.com, updated October 2020
- Hyperthyroidism. Patient. patient.info/doctor, last edited February 2020
- Hyperthyroidism in pregnancy. Patient. patient.info/doctor, last edited March 2020
- Hypothyroidism. Patient. patient.info/doctor, last edited February 2020
- Thyroid eye disease. Patient. patient.info/doctor, last edited December 2015
- Hyperthyroidism. MSD Manuals. msdmanuals.com, last full review/revision September 2020
- Hyperthyroidism. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised February 2020
- Hyperthyroidism. NICE British National Formulary. bnf.nice.org.uk, accessed November 2020
- Carbimazole. NICE British National Formulary. bnf.nice.org.uk, accessed December 2020
- Thyroid. Oxford Handbook of Endocrinology and Diabetes. Oxford Medicine Online. www.oxfordmedicine.com, published online March 2014
- Metabolism. Encyclopaedia Britannica. britannica.com, last updated October 2020
- Hair loss and thyroid disorders. British Thyroid Foundation. btf-thyroid.org, accessed November 2020
- Hyperthyroidism. British Thyroid Foundation. btf-thyroid.org, accessed November 2020
- Radioactive iodine (I-131) therapy. RadiologyInfo.org. radiologyinfo.org, reviewed January 2018
- After radioactive iodine treatment. Cancer Research UK. cancerresearchuk.org, last reviewed July 2018
- Jeffreys A, Vanderpump M, Yasmin E. Thyroid dysfunction and reproductive health. The Obstetrician & Gynaecologist, 2015; 17:39–45. doi: 10.1111/tog.12161
- Endometriosis. Patient. patient.info/doctor, last edited September 2020
- Polycystic ovary syndrome. Patient. patient.info/doctor, last edited June 2016
- Personal communication, Mr Robert Hardy, Consultant Surgeon, December 2020