Hydroxychloroquine and chloroquine are ineffective against COVID-19 and possibly harmful

A meta-analysis of clinical trial results shows that hydroxychloroquine and chloroquine are of no benefit to COVID-19 patients. 


The much-hyped drugs hydroxychloroquine and chloroquine have proved ineffective and probably harmful in treating COVID-19. All clinical trials involving the treatments have been stopped. LILIBOAS/ ISTOCK / GETTY IMAGES PLUS

An international team, including Yaseen Arabi of KAIMRC, has confirmed that treatment with hydroxychloroquine (HCQ) is associated with higher mortality in patients with COVID-19 and that there is no benefit to using chloroquine (CQ) to treat the disease. All COVID-19 clinical trials involving the two drugs have been stopped.  

“These two drugs are used for the treatment of malaria and rheumatic disorders, and scientists had been hopeful of their potential as treatments for COVID-19 thanks to their antiviral and immunomodulatory activity,” says Arabi. He served as the COVID-19 Antiviral Therapy Domain Chair of the REMAP-CAP trial, an ongoing international trial that tested HCQ, and is currently testing other therapeutics against community-acquired pneumonia and COVID-19.  

 HCQ and  CQ became a focus of multiple clinical trials as the COVID-19 pandemic took hold in early 2020. In several countries including the US and China, both drugs were listed as treatment options for patients in March and April 2020, even though they were known to cause potentially severe side effects. By June 2020, the FDA had revoked the emergency use authorization of the drug, following data emerging from two high-profile trials, the RECOVERY and WHO Solidarity trials.  

Arabi, along with many other scientists around the globe, contributed data from their own trials to the meta-analysis project to definitively determine the efficacy of the two treatments. The meta-analysis included data from 28 ongoing, completed, or discontinued randomized clinical trials, including the REMAP-CAP trial, that used either or both drugs to treat COVID-19. The team analysed data from more than 10,000 patients.   

“By including data from multiple RCTs, meta-analysis increases the power to detect differences in outcome related to individual therapies,” says Arabi. “In this case, it showed that  HCQ and  CQ were associated with poor outcomes.”  

Treatment with  HCQ was associated with a longer hospitalization and a higher risk of progression to invasive ventilation and/or death. Variation in the dosage did not alter these findings. No clinical benefit was found for  CQ either, although data was limited for this particular treatment.  

“The analysis provides conclusive proof that neither drug should be used for COVID-19, and all trials pertaining to these treatments have stopped,” says Arabi. “Thanks to the rapid, collaborative efforts made by scientists around the world, any further harm linked to  HCQ use in COVID-19 treatment has been prevented.”


  1.  Axfors, C. et al. Mortality outcomes with hydroxychloroquine and chloroquine in COVID-19 from an international collaborative meta-analysis of randomized trials. Nature Communications 12: 2349 (2021)article

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