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

HOW CAN VAPING BE HARMFUL? 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. E-cigarettes produce an aerosol by heating a liquid that usually contains nicotine. Aerosol is inhaled into the lungs and can contain potentially harmful substances, including heavy metals like lead, volatile organic compounds, and cancer-causing agents. US health officials, the Centers for Disease Control and Prevention (CDC), are investigating an outbreak of e-cigarette or vaping, product use associated lung injury (EVALI). The mystery illness has swept across the states. Officials have identified Vitamin E acetate, which is used in cannabis vaping products, as a chemical of concern. 'Popcorn lung' is the nickname for bronchiolitis obliterans, a condition which damages the smallest airways in the lungs and has been linked to people with vaping-related breathing problems. However, there’s no good scientific evidence that e-cigarettes could cause the lung condition, according to Cancer Research UK. The flavourings in electronic cigarettes may damage blood vessels in the same way as heart disease, according to research published in June 2018. The chemicals used to give the vapour flavours, such as cinnamon, strawberry and banana, can cause inflammation in cells in the arteries, veins and heart. They cause the body to react in a way that mimics the early signs of heart disease, heart attacks or strokes, the study by Boston University found. Other recent studies have also suggested smoking e-cigarettes could cause DNA mutations which lead to cancer, and enable pneumonia-causing bacteria to stick to the lungs more easily. Advertisement

Professor Prue Talbot, who led the research, said: 'Our data, which shows many of the symptoms characterizing the current patients have been reported online for at least seven years, suggests cases similar to those in the current VAPI epidemic have existed previously and been unreported or simply not linked to vaping.

'The sudden uptick in symptoms and conditions related to VAPI comes at least 10 years after e-cigarette products gained widespread popularity in the US.'

The research comes after the US last year saw a dramatic surge in the number of people being taken to hospital with health problems linked to e-cigarettes.

By December 31, 2,561 people had needed hospital treatment because of the devices and a total of 55 people had died in 27 states.

Officials say a chemical called vitamin E acetate, which is used in cannabis vaping products, is to blame for most of the cases.

Vaping has been touted as a healthier alternative to smoking because it doesn't contain cancer-causing tar or carbon monoxide.

But the health dangers of the habit are not well understood.

A study published in December suggested people who use e-cigarettes may be 29 per cent more likely to develop serious lung diseases such as asthma, bronchitis or emphysema than people who have never smoked.

And other research revealed in March found people who vaped every day were 34 per cent more likely to have a heart attack than non-vapers.

In the latest research, the team found 45 per cent of the health-related posts made in the forums were negative, while 38 per cent were neutral. Only 17 per cent were positive.

Some flavouring chemicals can expand blood vessels and make people get headaches or feel exhausted, while inhaling nicotine – which is found in e-cigarettes – is known to be able to cause headaches, feeling sick, mouth or throat pain and coughing or heartburn.

One of Professor Talbot's colleagues graduate student My Hua, said: 'Our data underscore the idea that e-cigarette use is not free of adverse health effects and suggest that the epidemic we are seeing now will continue to grow given the many reports in the forum of symptoms characteristic of VAPI.

'It is important that vigilant reporting of cases, tracking symptoms, and engaging in research on the health effects related to e-cigarette use be continued and expanded to understand and contain VAPI.'

The research was published in the Journal of Medical Internet Research.