An Ontario mother says she was scared to use her son鈥檚 EpiPen when she suffered a severe allergic reaction because she didn鈥檛 know when she could replace the life-saving device.

Pfizer, the only company that makes EpiPens, announced a shortage on July 30 due to a manufacturing issue. Canada has experienced a low supply of EpiPens since at least January, but Health Canada warned that pharmacies could totally run out sometime in August as they await shipments.

So when Michelle Nel from Prescott, Ont., was stung by a hornet four times while gardening last week, she hesitated. She immediately felt dizzy, but she didn鈥檛 want to use her son鈥檚 EpiPen.

鈥淚 knew what was going on, and it wasn鈥檛 as much denial that I was having a reaction. It was that I wasn鈥檛 ready to deal with this due to the EpiPen shortage,鈥 Nel told 麻豆影视.

She watched her arm swell and red hives spread across her skin. Even as her throat tightened, she waited.

Nel knew that if she used the EpiPen on herself, it would leave her 10-year-old son, Nolan, who is severely allergic to nuts, soy and other foods, with just one. On several occasions, Nel says, her son has needed two doses during life-threatening allergy attacks.

鈥淚f I used one of his EpiPens -- especially living in a rural community -- I didn鈥檛 know if I could replace it. And what if he needed it?鈥

Nel鈥檚 condition rapidly worsened. Eventually, when she felt she might pass out, she gave herself the injection.

鈥淭o think I鈥檓 taking away his life-saving medication, even though I was having an anaphylactic reaction, it was heart-wrenching for me,鈥 she said.

The shortage may be over soon. In a statement to 麻豆影视, Pfizer confirmed it is shipping auto injectors across Canada, which should reach pharmacies by the end of the week.

鈥淎dditional stock is expected to be released to the Canadian market in the coming weeks,鈥 the company said.

Dr. Susan Waserman, professor at McMaster University medical school鈥檚 division of clinical immunology and allergy, welcomes the news of supply replenishment -- but says we will have to see what additional stocks look like in the coming weeks.

鈥淚n the meantime, same advice on our end applies -- keep expired devices and use them if no current one available -- they are still effective. Check around different pharmacies, don鈥檛 fill multiple devices at one time, adults can use 2 juniors if that is all that is available,鈥 Waserman said. 鈥淭he unfortunate part for Canadians is that we are a single device country.鈥

Since 2017, there have been five EpiPen shortages. Nel said she can鈥檛 believe that, in 2018, a common, life-saving medication isn鈥檛 readily available in Canada.

鈥淚t鈥檚 unacceptable and it鈥檚 appalling,鈥 she said.

Meanwhile, Health Canada is reviewing a decision by the U.S. Food and Drug Administration to approve the expiry date extension for some EpiPen products.

The FDA approved on Tuesday a four-month extension of expiration dates for specific lots of 0.3 mg EpiPens marketed by Mylan that are expired or close to expiring.

鈥淲e are doing everything we can to help mitigate shortages of these products, especially ahead of the back-to-school season,鈥 said Janet Woodcock, director of the FDA鈥檚 Center for Drug Evaluation and Research, in a statement.

鈥淲e鈥檙e hopeful this action will ensure patients have access to this important medication and provide additional peace-of-mind to parents as the agency works with the manufacturer to increase supply.鈥

In a statement to 麻豆影视, Health Canada spokesperson André Gagnon said the agency is aware of the FDA notice and is working with Pfizer to assess the information. Each country has its own regulatory process for drug approval, which includes any changes in product instructions for use.

鈥淗ealth Canada will communicate a decision regarding the extension of the expiry date once we review the data that formed the basis of the FDA decision,鈥 the statement said.

Pfizer Canada spokesperson Christina Antoniou told The Canadian Press in April that it's not unusual to have short periods of reduced supply of the auto-injector.

鈥淭here鈥檚 a relatively short shelf-life on it of 12 to 18 months," she said, 鈥渟o between the relatively short shelf-life and managing the inventory supply, it's quite normal for us to experience periods of limited supply.鈥

With a report from CTV Medical Correspondent Avis Favaro and senior producer Elizabeth St. Philip and files from The Canadian Press