Iodine tablets: who should have them, and when to take them
Updated · 6 min read
New here? Start with our overview of home readiness: what to have ready, and why.
The Danish Health Authority recommends that iodine tablets are available for people under 40 and for pregnant and breastfeeding people, as part of home readiness.[1] At the same time, the tablets are only a supplement. In a nuclear accident, the most important advice is to stay indoors.[2]
In short: If your household includes anyone under 40, or anyone pregnant or breastfeeding, buy medical iodine tablets at a pharmacy and keep them at home. Only take them if the Danish Health Authority says so.[1]
Why iodine tablets?
In a nuclear accident the air can be contaminated with radioactive substances, including radioactive iodine. If you breathe it in, it is absorbed into the blood and concentrated in the thyroid gland, which in the long term can increase the risk of thyroid cancer, especially in children and young people.[1]
Iodine tablets saturate the thyroid with non-radioactive iodine and so block the uptake of radioactive iodine.[1] They don't protect against the other radioactive substances in a release and have no general protective effect against radiation.[1]
The best protection is to go indoors and close doors and windows until you're told the release has passed. If the authorities have asked you to stay indoors, don't go out to get iodine tablets.[1]
Who should have iodine tablets?
Everyone under 40 can benefit from iodine in a nuclear accident. Children and young people under 18 and pregnant and breastfeeding people benefit most, because they have the highest risk of developing thyroid cancer.[1]
People over 40 are not advised to take iodine tablets, because no link has been found between radioactive iodine and thyroid cancer in that age group. Pregnant and breastfeeding people are advised to take iodine regardless of age.[1]
Which tablets, and where to buy them?
Buy what are called medical iodine tablets ("medicinske jodtabletter"). They contain 65 mg potassium iodide, equal to 50 mg iodine, and are only sold at pharmacies. They are over the counter and need no prescription.[1]
Iodine dietary supplements from health food shops can't be used instead, because they contain far less iodine.[1]
Keeping the tablets at home means you don't have to go out if the authorities have asked you to stay indoors, and you can take them at the right time.[1]
- Medical iodine tablets, 65 mg potassium iodide
- Bought at a pharmacy
- Kept at home where you can find them
- Enough for everyone under 40 and anyone pregnant or breastfeeding
When should the tablets be taken?
Only take iodine tablets when the Danish Health Authority instructs you to, and never on your own initiative. Instructions are announced on radio and TV and on the Danish Health Authority's website.[1]
The tablets give the best protection if taken less than 24 hours before and up to 2 hours after exposure to radioactive iodine. Up to 8 hours after is still within a reasonable time. Never take them later than 24 hours after, because that can be harmful.[1]
Internationally, iodine tablets are only recommended within 100 to 200 km of a damaged nuclear power plant. Apart from Sweden's Ringhals, 65 km from the island of Læsø, all nuclear power plants are more than 200 km from Denmark.[1]
Doses by age
The Danish Health Authority recommends these single doses of tablets with 65 mg potassium iodide:[1]
- 12 to 40 years, and pregnant and breastfeeding people: 2 tablets (130 mg)
- Children aged 3 to 12: 1 tablet (65 mg)
- Children from 1 month to under 3 years: ½ tablet (32.5 mg)
- Infants under 1 month: ¼ tablet (16.25 mg)
- 40 and over: not recommended
One dose is usually enough, even if you have to stay indoors for a few days. Only take more doses on explicit instructions from the Danish Health Authority. Infants under one month may only be given iodine once, and pregnant and breastfeeding people at most twice.[1] Taking more tablets than recommended gives no extra protection.[1]
Is it safe?
Iodine tablets are generally safe, but rare side effects can occur, so only take the recommended dose. A few people must not take them, including people who are hypersensitive to iodine. If you have a thyroid condition, have your metabolism checked 6 to 12 weeks after taking them.[1]
Always read the package leaflet before taking iodine tablets.[1]
Instructions about iodine tablets are given on radio and TV. See how to choose an emergency radio, so you can keep up even if the power is out.
For the full list of what to keep at home, read on here: Emergency supply list: what to keep at home
Frequently asked questions
Should I keep iodine tablets at home?
The Danish Health Authority recommends that iodine tablets are available for people under 40 and for pregnant and breastfeeding people, as part of home readiness. People over 40 are not advised to take iodine tablets.
Which iodine tablets should I buy?
Medical iodine tablets with 65 mg potassium iodide. They are only sold at pharmacies, over the counter without a prescription. Iodine dietary supplements can't be used instead.
When should iodine tablets be taken?
Only when the Danish Health Authority says so, never on your own initiative. Instructions are announced on radio and TV and on the Danish Health Authority's website. Never take them later than 24 hours after exposure to radioactive iodine.
What is the most important protection in a nuclear accident?
Going indoors and closing doors and windows. Iodine tablets are only a supplement, because they protect only against radioactive iodine, not against the other radioactive substances in a release.
Sources
- [1]Danish Health Authority (Sundhedsstyrelsen): Jod og jodtabletter (in Danish) (2025-11-28)
- [2]Danish Emergency Management Agency (Beredskabsstyrelsen): Prepared for crises