The move came after two French advisory bodies and the World Health Organisation warned this week that the drug – also used as treatment for rheumatoid arthritis and lupus – had been shown to be potentially dangerous in several studies.
The drug had been heavily promoted by Marseille-based infectious disease specialist Didier Raoult, who caught the ear of Trump, who stunned his own administration last week by revealing he was taking hydroxychloroquine as a preventive measure against Covid-19.
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After Raoult's trials of the drug produced apparently positive results, France's health ministry licensed it for use on the most seriously ill patients, in hospital settings only.
But under the new French rules, the drug can be used only in clinical trials to test its efficacy against coronavirus – making it unclear if Professor Raoult would be able to continue using it at his hospital in Marseille in the south.
Raoult has already rejected a comprehensive study published last week in The Lancet medical journal, which found that administering hydroxychloroquine or its related compound chloroquine actually increased the risk of dying for many patients.
Hydroxychloroquine, also used to treat malaria, is sold under the brand name Plaquenil by French pharma giant Sanofi, which promised to offer governments millions of doses if studies proved it could be safely used in the coronavirus fight.
The French government has been running trials on several drugs – including AIDS, Ebola and hepatitis treatments – on seriously ill patients in hospitals to see if any can help in treating Covid-19 patients.