How iodine tablets work

Iodine is stored in the body’s thyroid gland, which uses it to make metabolic hormones. If the iodine is radioactive, it could cause thyroid cancer in the long term. Iodine tablets 'fill' the thyroid gland with stable iodine, so it cannot absorb the radioactive iodine, which is then excreted.

People must not take the iodine tablets until the authorities advise them to do so. This advice may be given at the same time as other measures in response to a nuclear accident, such as a regional evacuation order or instructions to go to a shelter. The advice will give information about who should take the tablets, where and when.

Iodine tablets should be taken shortly before exposure to radioactive iodine. This ensures a maximum blocking effect and protects the thyroid gland.

Iodine tablets only protect against radioactive iodine, not any other radioactive substances that may be released during a nuclear accident.