Health Canada says people who vape should get medical attention right away if they’re worried their electronic cigarettes are harming them.

The federal department says there is no sign in Canada of an affliction reported in as many as 25 American states that seems to be linked to vaping, but it is monitoring the situation.

Most of those who have fallen ill have been teens or adults in their 20s or 30s, hospitalized with severe shortness of breath, vomiting, fever and fatigue. Other symptoms include coughing, chest pain and diarrhea, and signs of infection, such as fevers, that appear without any apparent source.

Some patients have been successfully treated with heavy doses of steroids, a therapy typically used to calm inflammation. Some have narrowly avoided death, but two people, one in Illinois and another in Oregon, have died from lung illnesses.

Health investigators believe there are dozens of possible chemicals inhaled through vaping that could be causing what appears to be a severe inflammatory reaction in the lungs, a condition that looks a lot like pneumonia and that can essentially strangle the afflicted.

U.S. authorities from the Centres for Disease Control and Prevention and the Food and Drug Administration have been working with state investigators to identify what toxin or substance might be causing the problem.

Alexander Mitchell’s lungs had stopped working and he was in intensive care on two different life support systems for about a week — he escaped death, but two others did not. Mitchell Family / Washington Post - supplied

An investigator in Oregon told the New York Times that the second victim to die apparently became sick after vaping THC from a product purchased from a recreational marijuana shop in the state.

Dr. Ann Thomas, a paediatrician and public health physician who is leading Oregon’s incident management team, said the person died in July after being hospitalized and put on a ventilator. Thomas declined to identify the person or disclose their age or gender, but said the patient was “otherwise healthy and quickly became very ill.”

Thomas said that the doctor who treated the patient recognized several weeks later that the patient’s lung infection was consistent with a syndrome thought to be connected to vaping that has affected more than 200 people around the country this summer. She echoed other authorities in saying that she has heard that many cases involve THC, the high-inducing chemical in marijuana, but she cautioned that it is too soon to know for sure if marijuana-related vaping is a cause.

On Friday Canada’s CDC warned people not to use vaping ingredients bought on the street, and to stop modifying either nicotine or cannabis electronic cigarette devices. Health Canada is asking health workers to ask patients who come in with respiratory problems whether they use e-cigarettes, and is warning users not to modify them or use them in ways they’re not made for.

The fact that the person who died in Oregon appears to have legally purchased the product has reinvigorated a theory that the products making people sick are counterfeit, jury-rigged or tampered with by consumers or retailers mixing their own vaping liquids.

“At this point,” Thomas said, “we’d say we don’t really know what is safe.”

Officials need to keep finding ways to reach out to the public “to do what it takes to keep young people safe,” she added, “I know that sounds a little dramatic, but at this point we don’t know what’s causing it.”

Mark Pettinger, a spokesman for the Oregon Liquor Control Commission, which regulates marijuana sales in the state, said the agency is prepared to issue a recall of any product deemed unsafe.

Since November enforcement action has been taken against some 130 students in regards to vaping on school grounds. These are just some of the vapes and vape products confiscated by schools and turned over to By-law. Postmedia

Michigan on Wednesday became the first state in the U.S. to ban flavoured e-cigarettes.

The ban, which covers retail and online sales, goes into effect immediately and will last for six months, and can be renewed for another six months. In the meantime, state officials said, they will develop permanent regulations banning flavoured e-cigarettes. The state legislature could try to block those rules, but such legislation would face a veto, they added.

“In the absence of robust regulation by the Food and Drug Administration, we know shockingly little about the health impact of e-cigarettes being widely marketed to youth and adults,” Nancy Brown, chief executive of the American Heart Association, told the Washington Post.

While Michigan is the first state to prohibit sales of flavoured e-cigarettes, several cities and communities have restricted or banned sales. In late June, San Francisco became the first major city in the United States to ban the sale and distribution of all e-cigarettes.

In an undated image provided by Intermountain Healthcare, a CT scan of a vaping injury patient, looking up from the patient’s feet, with the cloudy areas in the lungs showing damage. Intermountain Healthcare via The New York Times

Kody Foster and his 4-year-old son Noah at the Tapering Vapor, an e-cigarette store, in Wilkesboro, N.C., May 20, 2016. George Etheredge/The New York Times

Vaping advocates are expected to oppose the Michigan ban as misguided and potentially harmful. While many concede the long-term effects of e-cigarettes are not known, they say vaping is almost certainly safer than traditional cigarette smoking, which is responsible for more than 480,000 deaths a year in the United States. Making it harder for smokers to get e-cigarettes means some smokers will go back to regular cigarettes, they say.