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Guide · GUIDE 05

Use iodine tablets correctly

Last reviewed on 09.10.2026

Iodine tablets (potassium iodide 65 SERB, 65 mg potassium iodide per tablet) are taken only on the instruction of the authorities. Children over 12 and adults take 2 tablets at once per day; for people over 45 years, taking them is no longer recommended. In Switzerland, they are distributed to the population as a precaution within a 50-kilometre radius around a nuclear power plant.

Iodine tablets (potassium iodide) saturate the thyroid with stable iodine so that it does not absorb radioactive iodine in the event of a nuclear power plant accident. Within a 50 km radius of the Beznau, Gösgen and Leibstadt nuclear power plants they are distributed to all households as a precaution; beyond that, the cantons keep stocks.

How do iodine tablets work in a nuclear accident?

In a serious nuclear power plant accident, radioactive iodine can be released. The thyroid absorbs iodine without distinguishing between stable and radioactive. Iodine tablets saturate the thyroid with stable iodine beforehand, so there is no room left for the radioactive kind.

Important: iodine tablets protect ONLY the thyroid. They are not a cure-all against radiation. That is why the following always applies as well: get inside, close windows and doors, switch off ventilation, follow radio and Alertswiss.

Tablets are taken ONLY on the instruction of the authorities. The authorities measure first, the instruction then follows via radio and Alertswiss – after that, take the tablets as quickly as possible. If taken too early, they lose their protective effect.

What you need to know

  1. Take ONLY on the instruction of the authorities (radio, Alertswiss)
  2. After the instruction, take them as quickly as possible – if taken too early, they lose their protective effect
  3. They protect ONLY the thyroid – that is why this also applies: stay inside
  4. Store in the closed original pack at room temperature (15–25 °C) in a fixed place
  5. Take with plenty of liquid and if possible not on an empty stomach; for children, dissolve in a drink and have them drink it immediately

Dosage (according to the package leaflet)

One tablet of potassium iodide 65 SERB contains 65 mg of potassium iodide, equivalent to 50 mg of iodine. The duration of intake is determined by the authorities.

  1. Children over 12 and adults: 2 tablets at once per day
  2. Children from the 4th year of life to 12 years: 1 tablet per day (the 4th year of life begins on the 3rd birthday)
  3. Children from the 2nd month of life to 3 years: ½ tablet per day
  4. Newborns up to 1 month: ¼ tablet, just once – even if older children are ordered to take the tablets for several days
  5. Pregnant and breastfeeding women: 2 tablets at once per day, on a maximum of 2 days

People over 45 years

  1. People over 45 years: taking them is no longer recommended. The risk of developing thyroid cancer decreases sharply with age – as a result, possible side effects of the tablets carry more weight.
  2. Anyone over 45 who is nevertheless considering taking them should get advice at a doctor's practice, pharmacy or drugstore.
  3. Exception: pregnant and breastfeeding women take the tablets even over 45.

Who must not take iodine tablets?

Do not take in the case of known hypersensitivity to iodine, an untreated overactive thyroid or the rare diseases dermatitis herpetiformis, iododerma tuberosum, hypocomplementaemic vasculitis and myotonia congenita (package leaflet).

Anyone who has an overactive thyroid that is well controlled with medication takes the tablets as stated in the package leaflet, continues the treatment and sees a doctor after the incident.

Note: this does not replace medical advice. If you have a known thyroid condition or iodine intolerance, clarify with your doctor now what applies to you in the event of an incident.

Who gets iodine tablets and where from?

Within a 50 km radius of the Beznau, Gösgen and Leibstadt nuclear power plants, iodine tablets are distributed to all households as a precaution. Beyond this zone, the cantons keep stocks and, in the event of an incident, distribute them within twelve hours of the order being given.

  1. Know where the tablets are at home (a fixed, known place)
  2. Do not throw expired tablets (past their expiry date) in the bin: keep them until the authorities request you to return them – then take them back to a pharmacy or drugstore
  3. Install Alertswiss to reliably receive the instruction to take them

Common mistakes

  1. Taking the tablets «just in case» – without the authorities' instruction no benefit, but a risk of side effects
  2. Believing iodine tablets protect the whole body – they only protect the thyroid
  3. Summarising the children's dosage incorrectly – follow the age grading exactly
  4. Taking them anyway over 45 without getting advice (exception: pregnant and breastfeeding women)
  5. Only taking the tablets but not staying inside
Iodine tablets: dosage by age group (potassium iodide 65 SERB, 65 mg)
Group of people Dose
Children over 12 and adults 2 tablets at once per day
Children from the 4th year of life (from the 3rd birthday) to 12 years 1 tablet per day
Children from the 2nd month of life to 3 years ½ tablet per day
Newborns up to 1 month ¼ tablet, just once
Pregnant and breastfeeding women 2 tablets at once per day, on a maximum of 2 days (the age limit does not apply)
Over 45 years No longer recommended – advice at a doctor's practice, pharmacy or drugstore

Take only on the instruction of the authorities; the duration is determined by the authorities. Distribution within the 50-km zone around a nuclear power plant. Based on the package leaflet for potassium iodide 65 SERB. Does not replace medical advice.

Frequently asked questions

How are iodine tablets dosed?

According to the package leaflet: Children over 12 and adults: 2 tablets at once per day · Children from the 4th year of life (from the 3rd birthday) to 12 years: 1 tablet per day · Children from the 2nd month of life to 3 years: ½ tablet per day · Newborns up to 1 month: ¼ tablet, just once · Pregnant and breastfeeding women: 2 tablets at once per day, on a maximum of 2 days. The duration is determined by the authorities.

Who receives iodine tablets in Switzerland?

Within a 50 km radius of the Beznau, Gösgen and Leibstadt nuclear power plants, they are distributed to all households as a precaution; outside this zone, the cantons keep stocks and, in the event of an incident, distribute them within twelve hours of the order being given.

Do iodine tablets protect against all effects of radioactivity?

No. Iodine tablets (potassium iodide) protect exclusively the thyroid gland by saturating it with stable iodine so it cannot absorb radioactive iodine. They are not a cure-all against radiation. Therefore, the following always applies: go indoors, close windows and doors, turn off ventilation and follow radio and Alertswiss.

Why is taking iodine tablets not recommended for people over 45?

The risk of developing thyroid cancer decreases sharply with age; as a result, possible side effects of the tablets carry more weight. That is why the authorities no longer recommend taking them over the age of 45. Anyone who is nevertheless considering it should get advice at a doctor's practice, pharmacy or drugstore. The exception is pregnant and breastfeeding women: they take the tablets even over 45. In principle, the tablets are taken only on the instruction of the authorities via radio or Alertswiss.

Official sources