Health officials in Wisconsin are investigating cases of people with severe lung disease who all reported recently vaping nicotine or marijuana oils, extracts or concentrates.

The Wisconsin Department of Health Services said there were 12 confirmed cases as of August 8. The department is investigating 13 other cases, according to CBS News. While the first patients were teens and young adults, there are now also older patients.

Symptoms have included shortness of breath, fatigue, chest pain, cough and weight loss. While patients have improved with treatment, it is not known if there will be long-term health effects, health officials said. They noted products consumed could include a number of substances, including nicotine, THC, synthetic cannabinoids, or a combination.

“We strongly urge people to avoid vaping products and e-cigarettes,” Wisconsin Department of Health Services Secretary-designee Andrea Palm said in a news release. “Anyone—especially young people who have recently vaped—experiencing unexplained breathing problems should see a doctor.”