A BBC team tracking coronavirus misinformation has found links to assaults, arsons and deaths. And experts say the potential for indirect harm caused by rumours, conspiracy theories and bad health information could be much bigger.
"We thought the government was using it to distract us," says Brian Lee Hitchens, "or it was to do with 5G. So we didn't follow the rules or seek help sooner."
Brian, 46, is talking by phone from his hospital bed in Florida. His wife is critically ill - sedated, on a ventilator in an adjacent ward.
"The battle that they've been having is with her lungs," he says, voice wobbling. "They're inflamed. Her body just is not responding."
After reading online conspiracy theories, they thought the disease was a hoax - or, at the very least, no worse than flu. But then in early May, the couple caught Covid-19.
"And now I realise that coronavirus is definitely not fake," he says, running out of breath. "It's out there and it's spreading."
A BBC team has been tracking the human toll of coronavirus misinformation. We've investigated dozens of cases - some previously unreported - speaking to the people affected and medical authorities in an attempt to verify the stories.
The effects have spread all around the world.
Online rumours led to mob attacks in India and mass poisonings in Iran. Telecommunications engineers have been threatened and attacked and phone masts have been set alight in the UK and other countries - all because of conspiracy theories.
And in Arizona, a couple mistakenly thought a bottle of fish tank cleaner contained a preventative medicine.
Poisoned by cleaning products
It was late March when Wanda and Gary Lenius started to hear about hydroxychloroquine.
The couple noticed a similar-sounding ingredient on the label of an old bottle that was lying around their house in Phoenix.
Hydroxychloroquine may have potential to fight the virus - but as research continues, it remains unproven. On Monday, the World Health Organisation halted its use in trials after a recent study suggested it could actually increase the risk of patients dying from Covid-19.
Speculation about its effectiveness started circulating online in China in late January. Media organisations, including Chinese state outlets, tweeted out old studies where it was tested as an anti-viral medicine.
Then a French doctor claimed encouraging results. Although doubt was later cast on that study, interest in hydroxychloroquine surged. It was mentioned, with various degrees of scepticism, by a variety of media outlets and influential people including Tesla chief executive Elon Musk and Brazilian President Jair Bolsonaro.
It also found its way into White House press briefings - and President Trump's Twitter feed.
"What do you have to lose?" he said on 3 April. "Take it." In mid-May, he went further - saying that he'd been following his own advice. Each comment resulted in big spikes in social media chatter about the drug, according to data from online monitoring tool CrowdTangle.
Overdoses of the drug are rare, but the anxiety produced by the pandemic has driven people to extreme measures.
In Nigeria, hospital admissions from hydroxychloroquine poisoning provoked Lagos state health officials to warn people against using the drug.
And in early March, a 43-year-old Vietnamese man was admitted to a poison control clinic in Hanoi after taking a large dose of chloroquine. He was red, trembling and unable to see straight. The clinic's director, Dr Nguyen Trung Nguyen, said the man was lucky he received treatment quickly - or else he might have died.
Gary Lenius was not so fortunate. The cleaner he and Wanda gulped down contained a different chemical, and was poisonous.
Within minutes, both started feeling dizzy and hot. They vomited and struggled to breathe. Gary died, and Wanda was hospitalised.
Wanda later explained why the couple drank the concoction.
"Trump kept saying it was pretty much a cure," she said.
In Iran, authorities say hundreds have died from alcohol poisoning after viral rumours about its curative effects.
The total was put at 796 by the end of April by Kambiz Soltaninejad, an official from Iran's Legal Medicine Organisation, who said it was the result of "fake news on social media."
The truth behind the number is murky in a country where alcohol is banned in Iran and bootleg moonshine is routinely contaminated.
However in this case, BBC journalists did see rumours of the supposed "cure" spreading on the messaging app Telegram before the official announcement.
Shayan Sardarizadeh of BBC Monitoring's disinformation team notes that the announcement was potentially embarrassing to the Iranian authorities and, if anything, the number could be an underestimate.
In one case we verified, a 5-year-old boy went blind after his parents plied him with illegal booze in an attempt to fight the disease.
"We know that bad information can ruin lives," says Clare Milne, deputy editor of UK fact-checking organisation Full Fact. "There's such great potential for harm."
'My friend ate soap'
President Trump has speculated on a number of other cures beside hydroxychloroquine. In late April, he opined that ultraviolet rays could neutralise the virus.
"And then I see the disinfectant where it knocks it out in a minute. One minute. And is there a way we can do something like that, by injection inside or almost a cleaning?"
Trump later said his comments were sarcastic. But some Americans didn't see it that way, and poison control hotlines received calls asking about the advice. Officials at one in Kansas said they heard from someone who said his friend swallowed disinfectant soap after the president's briefing.
Dr Duncan Maru, a doctor at Elmhurst Hospital in New York, says his colleagues have treated patients who have become acutely ill after ingesting disinfectant.
"These ingestions also can have long-term consequences, like cancers and gastrointestinal bleeding," he says.
Arsons, assaults and conspiracies
Social networks have also been fertile ground for conspiracy theories. One particular coronavirus-related one - there are many circulating online - has resulted in arsons and assaults.
Across the UK, more than 70 phone masts have been vandalised because of false rumours that 5G mobile phone technology is somehow to blame for the virus.
In April, Dylan Farrell, an engineer for Openreach, was driving his van in Thurmaston near Leicester. It had been a long day and he was thinking about what he might have for tea as he pulled up to a roundabout. That's when he started to hear shouting.
At first, he thought it was directed at someone else. But when he heard "5G!" being screamed through his passenger side window, he realised the shouting was meant for him.
"You've got no morals!" a man shouted. "5G is killing us all!"
"I have no doubt he would have tried to get inside and physically attack me had I not locked the doors straight away," Dylan says. "It was so frightening."
He drove away quickly. There have been no arrests in connection with the incident.
"We've seen a lot of conspiracies which have been online for a long time now about 5G," says Claire Milne of Full Fact. "Those have evolved to be connected to the new coronavirus."
Racial tensions and violent attacks
In March, WHO Director General Tedros Adhanom Ghebreyesus warned that the pandemic would lead to a flare up of a "dangerous enemy".
He was referring to racism against people from Asia and China, but the virus has exacerbated tensions in several countries.
In April, three Muslim men were violently attacked in separate incidents in Delhi. They were beaten up after rumours circulated that Muslims were spreading the virus.
In Sisai, a small village in eastern India, rival gangs clashed. It came after an attack on a Muslim boy, again linked to false rumours suggesting Muslims were spreading disease. One young man lost his life and another was seriously injured.
False reports have circulated within ethnic communities as well. In Bradford, England, rumours circulated that non-white patients were being left to die.
And in Indore, a city in west-central India, doctors on a mission to track down someone who might have been exposed to the virus were attacked with stones. Misleading WhatsApp videos claimed that healthy Muslims were being taken away by health care workers and injected with the virus.
Two doctors were left with serious injuries after the incident in early April.
Critically ill from conspiracies
Online disinformation can have direct consequences, and social media platforms such as Facebook said they'll remove coronavirus posts that pose an immediate threat.
But it can also have indirect or delayed effects.
"I hope she pulls through," says Brian Lee Hitchens, the patient in Florida who got sucked in by coronavirus conspiracy theories. "But if I do lose her, she'll be in a better place."
Brian and his wife didn't have one firm belief about the disease - instead they oscillated between thinking that the virus was a hoax, linked to 5G, or a real but mild ailment.
So they carried on as normal despite official warnings. Brian went to work as a taxi driver in his hometown of Jupiter. He went shopping and picked up his wife's medications. Despite his wife's sleep apnoea and asthma, he didn't bother with social distancing or wearing a mask.
Catching the virus brought Brian back to reality. He turned to social media, this time to warn people off of misinformation and conspiracy theories.
Experts say posts like Brian's may be more useful in combating conspiracies than news articles and fact checks.
"One of the most effective ways of trying to correct the record," says Full Fact's Claire Milne, "is by getting the person who made the original claim to do it themselves."
'We lose so many lives because of misinformation'
Brian's may be an extreme case, but with the sheer amount of information circulating - the WHO has called it an "infodemic" - many other people have been misled by what they read online.
They're not killing themselves by taking fake cures. Instead, they're lowering their chances of survival by not thinking coronavirus is real or serious.
On an unusually cold Friday in May, two men in their forties arrived at an emergency hospital in the New York borough of Queens. They were roommates, working long shifts and sharing a single bed, and both were seriously ill.
Within hours, Dr Rajeev Fernando saw one die in front of his eyes. The other was put on a ventilator.
Dr Fernando asked the men why they hadn't come to hospital sooner. They explained to him that they read somewhere online that the virus wasn't very serious.
"They try alternative therapies," Dr Fernando says. "They think this is just like the flu."
The men were in at-risk groups - but Dr Fernando believes they would have fared better if they had ignored the misleading advice and sought help sooner.
Professor Martin Marshall, chair of the Royal College of General Practitioners, says he and his colleagues in the UK have seen patients taking tips from posts they see online - including holding their breath in an attempt to "diagnose" themselves or thinking that drinking hot drinks will fight off the virus. Some have cited President Trump's statements about disinfectant.
Dr Maru, the doctor at New York's Elmhurst Hospital, calls the numbers who have potentially delayed treatment "staggering."
He knows of neighbours who have caught the disease and died because they believed that social distancing is ineffective or that coronavirus is a hoax. And he says that he and his colleagues spend precious time trying to debunk misinformation when they could be treating patients.
But as he spoke on the phone, exhausted and preparing to return to Elmhurst for another shift, Dr Maru was also quick to shift the blame away from the patients themselves.
"Misinformation is a structural problem," he says. "Blaming somebody for ingesting bleach or for staying at home and dying is akin to blaming somebody who is walking down the street and gets hit by a drunk driver."
In response to the wave of misinformation, social media companies have drawn up new rules. In a statement, Facebook said: "We don't allow harmful misinformation and have removed hundreds of thousands of posts including false cures, claims that coronavirus doesn't exist, that it's caused by 5G or that social distancing is ineffective." The company also says it has put warning labels on 90 million pieces of content.
YouTube says it does not allow content promoting dangerous so-called cures and has a range of policies against Covid-19 misinformation, including disputing the existence of the disease or suggesting that it is caused by 5G.
What lies ahead
But as research continues into a coronavirus vaccine, many anti-vaccination and conspiracy-minded groups and accounts have seen their numbers swell. They pose a potential health threat - albeit not an immediate risk.
What some doctors we spoke to fear the most is that the development of a coronavirus vaccine - something that would be a human achievement for the ages - could be completely undermined by misinformation.
The future is scary, medical professionals say, because of what they're seeing right now.
"We lose so many lives. They come in very late," says Dr Fernando in New York. He's just finished a night shift, and as we talk on Skype, a protective mask dangles from his ears. "And we just watch them die in front of our eyes."
Brian, the coronavirus patient in Florida, has a message for the people who still believe in the conspiracy theories he endorsed just a few days ago.
"Don't be foolish like I was," he says, "and the same thing won't happen to you like it happened to me and my wife."
With reporting by Khue Luu Binh, Flora Carmichael, Alistair Coleman, Shruti Menon, Olga Robinson, Shayan Sardarizadeh, and a BBC Persian journalist.
Update 24 August: Brian Lee Hitchens' wife Erin - who was critically ill in hospital with Covid-19 at the time of publication - has since died from heart problems linked to the virus.
Is there a story we should be investigating? Email Marianna
- 4 May