The number of people suffering from these serious lung diseases has reached 215, spread across 25 states in the United States, announced Friday the Centers for Disease Control and Prevention (CDC). One death was reported last week.
The investigators did not identify a specific brand or product that caused these diseases, which manifested as coughing, shortness of breath, chest pain, and in some cases vomiting and diarrhea.
But in "many cases" cannabis substances had been used by the patient.
The vapoteurs are not to buy refills or liquids in the street, especially THC, the psychoactive substance of cannabis.
They "should not change e-cigarettes products or add them to substances that are not intended by the manufacturer," the CDC and the Food and Drug Administration (FDA) warned in a statement.
"Regardless of the current investigation, e-cigarette products should not be used by young people, young adults, pregnant women and adults who currently do not use tobacco," the authorities said.
Vaping is the process of inhaling vapors created by high temperature heating of a liquid inside the electronic cigarette. If nicotine is the norm, cannabis use is spreading.
The US authorities are particularly alarmed by the popularity of teenage vaping and have launched a policy of firmness against manufacturers to enforce the ban on sales to under 18 or 21 years, depending on the state.
The US market leader, Juul, is under investigation by the Federal Consumer Protection Agency for its marketing practices.