Potassium iodide in Australia: who decides and when?

Short answer. In a radiological or nuclear emergency in Australia, state or territory authorities decide whether to distribute potassium iodide, and you should take it only when public authorities advise you to ¹. It needs no prescription: at thyroid-blocking doses iodine is a Schedule 2 Pharmacy Medicine, and tablets supplied under an approved emergency plan are unscheduled ². The one thyroid-blocking product on the national register is THYRO-BLOCK 130 mg ³.

Who decides on potassium iodide in Australia?

State and territory authorities. ARPANSA, the national radiation protection agency, says that "in the rare event of a radiological or nuclear emergency in Australia, the decision to distribute potassium iodide tablets will be made by state or territory authorities" ¹. The public authorities responsible for distribution should be identified in state and territory emergency response plans ¹.

If the emergency happens overseas, ARPANSA advises the Department of Foreign Affairs and Trade (DFAT) on whether Australians abroad should take potassium iodide. Unless Australian authorities advise otherwise, follow local emergency services and health authorities, and stay informed through Smartraveller ¹.

Are iodine tablets handed out in advance?

No national household pre-distribution is described in the official guidance ¹. ARPANSA says that people near the site of an emergency are the most likely to need potassium iodide and will be told by public authorities if they should take it; people further away should not take it unless advised ¹.

Can I buy potassium iodide in Australia?

Yes, without a prescription, but there is little on the shelf. The Poisons Standard places iodine for internal use at 300 micrograms or more per daily dose in Schedule 2 (Pharmacy Medicine), "except in oral preparations for use in prophylaxis and treatment in the event of radioactive iodine exposure under an emergency plan approved by an appropriate authority", which are unscheduled ².

The Australian Register of Therapeutic Goods lists THYRO-BLOCK potassium iodide 130 mg, sponsored by ANSTO, as a registered non-prescription medicine with no poison schedule, for "thyroid blocking in a radiation emergency only" ³. Its sponsor declared no turnover for it in 2025-26 ³, so it may not be on retail sale. ARPANSA warns that potassium iodide bought from a chemist or pharmacy may not come in the recommended strength, so check the label ¹. Do not take it on a "just in case" basis ¹.

What dose should I take, and when?

Only the dose for your age group, and only when public authorities advise it ¹:

Source: ARPANSA ¹. For babies and young children, tablets can be crushed into a solution; ARPANSA gives the method in an appendix to its note ¹.

Timing matters. The best window is less than 24 hours before expected exposure and up to 4 hours after; some protection remains up to 8 hours after, very little between 8 and 24 hours, and starting later than 24 hours is not recommended ¹. One dose protects the thyroid for about 24 hours ¹. Children, adolescents and pregnant women benefit most; people over 40 are likely to benefit less ¹. If you have a thyroid condition, kidney disease or a possible iodine sensitivity, tell the authorities or a doctor before taking it ¹. Our general guide Potassium iodide (KI): when to take it and who needs it explains how iodine works.

What else should I read?

Potassium iodide only protects the thyroid from radioactive iodine; it does not protect the rest of the body ¹. It works alongside sheltering, avoiding contaminated food and water, and evacuation when authorities order it ¹. See Shelter in place or evacuate after a nuclear emergency? and How far do emergency zones around nuclear plants extend?.

Frequently asked questions

When should I take potassium iodide in Australia?

Only when public authorities advise you to, ideally within 24 hours before or up to 4 hours after exposure to radioactive iodine ¹.

Who would distribute iodine tablets?

State or territory authorities, named in their emergency response plans ¹.

Do I need a prescription for potassium iodide?

No. At thyroid-blocking doses it is a Schedule 2 Pharmacy Medicine, and tablets supplied under an approved emergency plan are unscheduled ². The registered product THYRO-BLOCK 130 mg is a non-prescription medicine ³.

I am an Australian abroad. Who advises me?

ARPANSA advises DFAT, which advises Australians overseas; otherwise follow the local authorities where you are ¹.

Sources

1. ARPANSA — Advisory note to RPS G-3 - Use of potassium iodide during a radiological or nuclear emergency — https://www.arpansa.gov.au/regulation-and-licensing/regulatory-publications/radiation-protection-series/guides-and-recommendations/guide-radiation-protection-emergency-exposure-situations-rps-g-3/advisory-note-rps-g-3-use-potassium-iodide-during-radiological-or-nuclear-emergency (accessed 2026-10-21)
2. Federal Register of Legislation — Therapeutic Goods (Poisons Standard—June 2026) Instrument 2026 (F2026L00633) — https://www.legislation.gov.au/F2026L00633/asmade/2026-05-28/text/original/pdf (accessed 2026-10-21)
3. Therapeutic Goods Administration (TGA) — THYRO-BLOCK potassium iodide 130mg tablet bottle (ARTG 58351) — https://www.tga.gov.au/resources/artg/58351 (accessed 2026-10-21)