The singer, who was admitted to an Australian hospital with husband Tom Hanks, says she was given chloroquine after developing a fever of 38.9C

The singer Rita Wilson has claimed to have suffered “extreme side effects” after being treated with the experimental Covid-19 drug chloroquine in an Australian hospital.

Wilson, who was touring Australia, and her husband, Tom Hanks, who was filming a Baz Luhrmann film about Elvis Presley, both tested positive for Covid-19 on 12 March while in Australia.

The drugs chloroquine and hydroxychloroquine are used to treat malaria, but their ability to treat Covid-19 is still disputed by experts, despite being touted by the US president, Donald Trump, as a “gamechanger”.

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Wilson and Hanks were admitted to Gold Coast University hospital in Queensland for treatment, where Wilson said she was given chloroquine after she developed a fever of 38.9C.

Q&A What is hydroxychloroquine? Show Hide Hydroxychloroquine, also known by its brand name, Plaquenil, is a drug used to treat malaria. It is a less toxic version of chloroquine, another malaria drug, which itself is related to quinine, an ingredient in tonic water. A widely publicized study in France where 40 coronavirus patients were given hydroxychloroquine, with more than half experiencing the clearing of their airways within three to six days has led to it being touted in some quarters as a potential cure for Covid-19. This apparent improvement is important as it would curtail the timeframe in which infected people could spread Covid-19 to others. However, experts have warned that the study is small and lacks sufficient rigour to be classed as evidence of a potential treatment. The French study followed work by Chinese researchers which suggested that hydroxychloroquine can slow infections by blocking the virus behind Covid-19 from entering cells in the body. But more recent, albeit small-scale, research from China has shown that patients who were treated with the drugs fought off coronavirus no more quickly than those who didn’t get it. Indeed, one patient given hydroxychloroquine severely worsened in condition while four patients on the medicine developed signs of liver damage and experienced diarrhoea. US president Donald Trump has claimed he takes hydroxychloroquine despite FDA warnings. Here is a guide to the scientific studies into hydroxychloroquine and coronavirus carried out so far. Regardless of these findings, any drug being used for a certain purpose before full clinical trials are completed is, by definition, untested and unproven. It’s too early to say if hydroxychloroquine can have a major benefit or not. The European Medicines Agency, an agency of the EU, has said hydroxychloroquine should not be taken by coronavirus patients except for clinical trials or emergency use programs. Oliver Milman

“They gave me chloroquine,” she told American TV channel CBS. “I know people have been talking about this drug. But I can only tell you that – I don’t know if the drug worked or if it was just time for the fever to break.

“My fever did break but the chloroquine had such extreme side effects, I was completely nauseous, I had vertigo and my muscles felt very weak … I think people have to be very considerate about that drug.”

A spokeswoman for Gold Coast University hospital would not confirm whether Hanks and Wilson were given chloroquine, but said that “selected patients” did receive the drug.

“Gold Coast Health has used a variety of medication in patients with more severe Covid-19,” a spokeswoman said. “Chloroquine, hydroxychloroquine and lopinavir-ritonavir have been used on selected patients.”

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Trump proclaimed the chemical’s effectiveness in March, but the US’s top infectious diseases adviser, Dr Anthony Fauci, has warned that there is not enough medical evidence to prove that it is useful.

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Australian researchers have also said it could cause potentially life-threatening side-effects, such as heart damage.

In March, a man in Arizona died after taking chloroquine phosphate – a chemical used to clean fish tanks – after Trump’s advice. “Trump kept saying it was basically pretty much a cure,” his wife told NBC.

Last week, the Australian Health Protection Principal Committee – the expert panel on health emergencies – recommended against using the drugs in hospitals, contradicting the federal health department.

The department has told hospitals they can prescribe the drug “in a controlled environment in the treatment of severely ill patients in hospital”, after the government waived therapeutic goods registration requirements to fast-track their import into Australia.

Wilson and Hanks have both recovered from the illness, and said their blood had been taken for a study to determine the level of antibodies they developed.