Side effects of radioactive iodine

Many people do not have any side effects after radioactive iodine treatment. You may have the following side effects:

  • Soreness or tightness around your neck or in the surgical scar.
  • Feeling a bit sick (mild nausea). This usually only lasts for a couple of days.
  • A dry mouth. This is not common during treatment, but it may happen once you go home. It can help to drink plenty of fluids.
  • Taste changes. This may not happen during treatment, but it can happen days or weeks later. It usually gets better within 4 to 8 weeks.

It is important to let your doctor or nurse know if you have any of these symptoms, as they can prescribe medicines to help.

Rarely, a dry mouth can become a long-term side effect of radioactive iodine treatment. This usually only happens if you have had more than one treatment. It happens if the salivary glands absorb the radioactive iodine. Let your doctor or specialist nurse know if you get a dry mouth or if it doesn’t improve. They will be able to help you manage it.

Pregnancy and fertility

After radioactive iodine treatment, you should not:

  • become pregnant for at least six months
  • father a child for at least four months.

It is important to use contraception during this time.

Radioactive iodine treatment does not normally affect fertility. But there is a very small risk for men who need to have more than one treatment. In this case, you may be offered sperm banking. Women have a slightly higher risk of a miscarriage in the first year after radioactive iodine treatment. Your doctor or nurse can give you more information and support about this.

Travelling after radioactive iodine treatment

For up to six months after radioactive iodine treatment, you may set off security radiation alarms at airports. It is a good idea to take the written information from the hospital, or a letter from your doctor, explaining the treatment you have had.

Back to Radioactive iodine

What is radioactive iodine?

Radioactive iodine is a type of radioisotope often used to treat thyroid cancer. It is given as a drink or capsule.