The Milwaukee Health Department is issuing a stern warning against vaping.
"Stop using any vape and/or e-cigarette devices immediately," the department said Wednesday in a news release.
As of Tuesday, the Health Department said there have been 16 people hospitalized with chemical pneumonia, which causes inflammation of the lungs.
"After two people, we should probably have sent out word sooner, but I'm glad we're doing it now," said Milwaukee Alderman Mike Murphy, who supports the Milwaukee Health Department's warning.
The patients each reported using vape products or marijuana oils, extracts or concentrates in the weeks and months prior to hospitalization.
The details of the causes were not yet known, the Health Department said.
"Residents are again strongly encouraged to not utilize any THC products containing e-liquid," the release said.
The patients are from 10 Wisconsin counties.
“We continue to learn more about the health effects associated with e-cigarettes. As the public health authority for the city, the MHD is committed to protecting the public from the dangers of secondhand exposure,” Commissioner of Health Dr. Jeanette Kowalik said.
"I understand citizens are going to say and business owners: 'Hey, this is a legal product. I can sell it.' They can, but I think the health commissioner has to take it to a higher level," Murphy said.
Symptoms of chemical pneumonia include coughing, shortness of breath, fatigue, fever, chest pain, nausea and diarrhea.
“The American Lung Association echoes the Milwaukee Health Department’s warning today to e-cigarette users: ‘Stop using any vape and/or e-cigarette devices immediately," the group said in a statement to WISN 12 News. "E-cigarettes contain toxic chemicals, heavy metals and fine particles, and the inhalation of these chemicals can cause irreversible lung damage and lung disease. The developing lungs of youth may be more at risk."
Anyone experiencing symptoms is urged to contact a doctor.
A vaping death was reported in Illinois last week.
There have been at least 193 vaping-related illness cases reported in 22 states across the country.