Both the Canadian and U.S. governments earlier this week said the threat of radioactive clouds reaching North American shores from the earthquake-damaged reactors in Japan was minimal, but that hasn't slowed a rush on potassium iodide tablets or liquid, the Canadian Broadcasting Corp and Fox News said.
British Columbia Provincial Health Officer Dr. Perry Ken told a news conference in Vancouver pharmacies were being advised to stop selling the over-the-counter medicine to prevent panic, the CBC said.
Meanwhile, potassium iodide pills were all but sold out in Oregon, California and Hawaii, Fox News said.
The medication is used to treat low-level radiation poisoning by protecting the thyroid gland, one of the body's most susceptible to radiation poisoning.
Officials in both countries have said even in the catastrophic event of a core meltdown in Japan's damaged reactors, prevailing westerly winds would take at least five days to carry radioactivity to the west coast, by which time it would have dissipated to negligible levels, the report said.
Three reactors at Japan's nuclear power plant in Fukushima are in critical condition after explosions and fires released radioactive steam as a result of Friday's magnitude-9 earthquake and tsunami.