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Health Concerns

Potassium iodide

Potassium iodide (KI) may be used to help protect the thyroid gland from radioactive iodine that may be released into the air during a radiological emergency. KI does not protect any other part of the body other than the thyroid gland. It does not protect against any other radioactive substance other than radioactive iodine.

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Q: Why is it used? How does it work?

A: The thyroid gland will use any iodine that is in a person's bloodstream. It cannot tell the difference between radioactive iodine and non-radioactive iodine (stable iodine). The absorption of radioactive iodine can be prevented by taking KI soon after its release into the air. Because the thyroid rapidly absorbs any iodine in the bloodstream, taking KI will load up the thyroid gland so that there is no space left for the radioactive iodine to be absorbed. The radioactive iodine will harmlessly be excreted in the urine.

Q: When and how should it be used?

A: KI works best when it is taken immediately before (about one-half hour) or as soon as possible after exposure. KI should only be taken when directed by public health officials. Not all radiological emergencies involve radioactive iodine and it is only required when there are significant amount of radioactive iodine present.

As the damaged nuclear power plant in Japan is not expected to pose a risk to residents of British Columbia or the rest of Canada, Health Canada does not recommend Canadians take KI. Like many medications, doses vary for people of different ages, and some people may have an adverse reaction to KI and may need medical attention.

KI should not be taken unless there is a clear public health recommendation to do so.

Q: What actions should Canadians take to protect themselves from radiation exposure as a result of the damaged nuclear power plants in Japan?

A: As the damaged nuclear power plant in Japan is not expected to pose a risk to residents of British Columbia or the rest of Canada, Health Canada does not recommend Canadians take any specific actions to protect themselves from this radiological emergency, including the purchase or consumption of KI. Like many medications, doses vary for people of different ages, and a small fraction of the population may have an adverse reaction to KI and may need medical supervision.

KI should not be taken unless there is a clear public health recommendation to do so.

Q: What are the potential adverse reactions to KI?

A: KI tablets are not recommended for use by people in Canada concerned about potential risks from the damaged nuclear power plants in Japan. KI tablets can present a danger to people with allergies to iodine or for people who have thyroid problems.

Oral consumption of KI may result in allergic reactions including hives, difficulty breathing, swelling around the eyes and throat, or joint aches and pains. It can also result in "iodism" in some people which can include salivation, sneezing, headache, fever, laryngitis, bronchitis and various skin rashes. It may also cause nausea and vomiting in some people.

Q: Does KI have any uses other than protecting the thyroid gland from radioactive iodine?

A: As the damaged nuclear power plants in Japan are not expected to pose a risk to residents of British Columbia or the rest of Canada, Health Canada does not recommend Canadians take KI. More importantly, there are potential risks to your health from taking it when it's not necessary. Consumers should not take KI to protect their thyroid from radioactive iodine unless there is a clear public health recommendation to do so, who will advise you on how much to take, how frequently to take it, and for how long to take it.

KI does have other therapeutic uses. For example, KI may be used to break up mucus in long-term lung problems such as asthma and emphysema, and to treat thyroid conditions.

Like many medications, the recommended dose varies for people of different ages, and a small fraction of the population may have an adverse reaction to KI and may need medical supervision. As well, KI tablets can present a danger to people with allergies to iodine, or who have thyroid problems (note: a seafood or shellfish allergy does not necessarily indicate allergy to iodine).

Q: If available in pharmacies, is a prescription needed?

A: KI is available from pharmacies without a prescription. However, authorities such as British Columbia's senior Medical Officer have advised pharmacies not to sell KI to consumers who are worried about the effects of the radiation release in Japan as there is no evidence that it is necessary. Furthermore, there is a chance that people could harm themselves by taking it when they don't need to. Inappropriate sales and stockpiling are also creating shortages that could adversely affect those consumers who have a real medical need for KI.