Nearly half of UK adults online have been exposed to false or misleading information about coronavirus in the past week, Ofcom has warned.
A new report by the media regulator found many people are also struggling to tell what is true or false in relation to the Covid-19 outbreak.
It follows calls from senior MPs and other organisations to better hold social media companies to account over disinformation.
Culture Secretary Oliver Dowden spoke to Facebook, Twitter and Google on Wednesday to discuss how they could clamp down further on content.
It comes as a range of false claims about the virus continue to spread online.
Mr Dowden welcomed progress made and the companies agreed to continue to work together to address disinformation and fake news, at speed, and to intensify the collaboration.
Since the lockdown began, Ofcom says 35% of adults online have seen the false claim that drinking more water can flush out the infection.
The regulator warned around 24% of adults had seen false claims that gargling with salt water or avoiding cold food or drink can also stop the virus.
Although more than half - 55% - say they are ignoring false claims, one in 14 said they were forwarding on disinformation.
A further 15% of adults online said they were using fact-checking tips.
Forty percent of those surveyed also said they found it hard to determine what was true or false about the virus, a figure which rises to more than half among 18 to 24-year-olds.
Younger people were also found to be following official advice less closely, the regulator reported, with only 43% of those aged 18-24 saying they were following hand-washing advice very closely.
According to the study of 2,000 people, almost all of adults online in the UK are getting news and information about the virus every day - with one in four doing so 20 or more times a day.
Shadow Secretary of State for Digital Culture Media & Sport, Jo Stevens, says more needs to be done to tackle disinformation:
Official sources such as the World Health Organization (WHO), the NHS and the Government were the next most popular sources of information, used by 52% of people.
Strikingly, the figures suggest that more people are turning to social media than newspapers.
A total of 49% of respondents said they used social media platforms to get news compared with 43% who looked to the papers.
Fifteen percent of those polled also said they used closed messaging groups, such as WhatsApp or Facebook Messenger, to get information.
Yih-Choung Teh, Ofcom's group director for strategy and research, said: "People are turning to public authorities and traditional broadcasters for trusted information about Covid-19, and the vast majority say they're closely following official advice.
But added: "With so much false information circulating online, it's never been more important that people can cut through the confusion and find accurate, trustworthy and credible sources of news and advice."
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