Doctors in the US have warned that the reagent used in some of the rapid antigen tests (RATs) available in Australia may be harmful, and even toxic in children.

Many of the COVID-19 kits available for home-testing contain sodium azide as a component of the reagent solution, they write in the American Journal of Emergency Medicine. 

The chemical is water-soluble, tasteless and odourless and commonly used as a preservative agent.

However, they warn it is “well known for its ability to cause harmful effects”, most notably rapid hypotension in relatively small doses.