By Kelly Johnson-Arbor, MD, Nicole Reid, BSN & Susan Smolinske, Pharm D

The persistence of the COVID-19 pandemic has necessitated the development and widespread availability of methods to detect the COVID-19 virus in humans. COVID-19 tests, which were initially only available in healthcare facility settings, are now manufactured for home use in the form of rapid diagnostic tests and generally contain a nasal swab, reagent solution, and test device (e.g., card or strip). These kits typically involve application of reagent solution to the test device; in the presence of biological material obtained from the nasal swab, this initiates a chemical reaction that produces the test result.

Multiple COVID-19 rapid antigen home test kids, including those manufactured by Abbott (BinaxNOW™), Beckton, Dickinson and Company (BD Veritor™), Celltrion (Celltrion DiaTrust™), and ACON Laboratories (Flowflex™), contain sodium azide as a component of the reagent solution. The reagent in some kits may contain other constituents, including Triton-X, inorganic phosphate, and Pro-Clin 300.

The latter ingredients are unlikely to cause human toxicity if small amounts are ingested, but they may cause allergic reactions or local irritation after ocular or dermal exposure. However, sodium azide is well-known for its ability to cause harmful effects in humans, especially after oral exposures and potentially including the ingestion of reagent solution. Additionally, since the reagent solution packaging may include ampules that allow for application of drops of solution to the test device, inadvertent ocular sodium azide exposures can occur if the ampule is mistaken for an eyedropper.

In some COVID-19 rapid test kits, the small bottle of reagent fluid contains sodium azide, a powerful poison that is particularly dangerous for small children, experts warn.

In adults, small amounts can quickly cause dangerously low blood pressure, dizziness, fainting, or even heart attacks or strokes, said Dr. Kelly Johnson-Arbor, Co-Medical Director of the National Capital Poison Center in Washington, D.C. Higher doses can be fatal, she and her colleagues wrote.

Sodium azide levels in COVID-19 rapid test kits are not always high enough to cause low blood pressure in adults, and the iHealth kits being sent out by the U.S. government do not contain any sodium azide at all, Johnson-Arbor said. "However... since children are typically much smaller than adults, they are at a higher risk of experiencing poisonous effects after swallowing any amount," she said.

Poison control hotlines have been getting reports of accidental exposures to the reagent fluid. "Some people have swallowed the solution, some have spilled it onto their skin, and others have put it in their eyes," mistaking the bottle for eye drops, Johnson-Arbor said. "If you or a loved one swallows the reagent fluid or gets the fluid in their eyes or on the skin, contact Poison Control right away." (In the U.S., at www.poison.org or 1-800-222-1222)