E-cigarettes may have been making people ill for at least 12 years, experts have warned.
Scientists trawled through online forums and found vapers have been complaining about the gadgets making them ill since 2008.
The analysis of 41,000 posts revealed hundreds of e-cigarettes users have reported having asthma, sore throats, coughs and colds.
Experts say the symptoms are similar to ones being shown by scores of US patients who have become poorly after using e-cigarettes.
Researchers now fear thousands of vaping-related illnesses have gone unreported, given their findings.
The US vaping illness crisis was forced into the limelight last year following a spate of deaths and 55 people have since died.
Doctors also officially recognised a specific condition – vaping-associated pulmonary illness (VAPI) – for the first time last year.
People using e-cigarettes have reported developing headaches, coughs, feeling sick, tiredness, dehydration, sore throats and asthma (stock image)
By the end of 2019, 55 people had died from vaping-related illnesses in 27 states in the US, according to official statistics – people have been killed in Alabama, California, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Kansas, Louisiana, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah and Virginia
A team of researchers from the University of California, Riverside, conducted the study by using a computer program to screen 41,216 comments online.
The posts were made in 'major electronic cigarettes online health forums' between 2008 and 2015. The scientists did not name the websites.
E-cigarettes were invented almost 20 years ago and came onto the market in the US, where the study was done, in 2007.
Their global popularity has soared since then and there are now an estimated one billion e-cigarette users around the world.
The researchers trawled through comments looking for key words and managed to build a picture of which symptoms people had been saying they suffered from.
Headache was the most common complaint, being mentioned 939 times, along with asthma (916), coughing (852), feeling generally unwell (468), dehydration (803) and a sore throat (565).
And complaints about more serious medical problems also cropped up, including pneumonia, diabetes and chronic obstructive pulmonary disease (COPD).
Among the top symptoms complained about online in e-cigarette forums were headaches, coughing, throat pain and heartburn, according to University of California researchers
People in the forums also mentioned specific illnesses, including the lung conditions asthma, chronic obstructive pulmonary disease (COPD), pneumonia and bronchitis
E-cigarettes have the potential to benefit some people, by helping them quit smoking. But scientists still have a lot to learn about whether e-cigarettes are truly effective for quitting smoking and what the long-term risks are.
Nicotine is already known to be highly addictive and harm adolescent brain development, which continues into the early to mid-20s.sonos sonos One (Gen 2) - Voice Controlled Smart Speaker with Amazon Alexa Built-in - Black read more
E-cigarettes produce an aerosol by heating a liquid that usually contains nicotine.