Reported ADRs with chloroquine or hydroxychloroquine

    The number of adverse drug reactions (ADRs) concerning chloroquine or hydroxychloroquine reported to the USA's FDA Adverse Event Reporting System (FAERS) has dramatically increased during the COVID-19 pandemic, according to study results reported in Annals of Internal Medicine.

    The study evaluated the change in reports since the pandemic began compared with reports in 2018 and 2019. There were a total of 21 305 reports, involving 152 201 suspected ADRs. The number of reports was higher in 2020 up to 30 September (n=11 493) than in the same months for 2018 (n=4681) or 2019 (n=5131). The number of reports classified as serious was also increased (97.1% vs 73.4% and 84.8%, respectively), as were the number of fatal reports (5.1% vs 3.1% and 1.9%). The higher proportion of serious or fatal events may be due to "changes in patient characteristics, comorbid conditions, and coprescription with other medications that may interact with these drugs, as well as higher dosages or drug pharmacokinetic modifications in patients with COVID-19", note the authors. They add that "the types of ADRs seemed to be similar over time", and "the ages of the patients who reported ADRs were similar in the 3 periods studied".

    The increased reporting "raises concerns about the potential harms of widespread use of these medications in the absence of proven benefits", conclude the authors.


    1. Perez J, et al. Reported Adverse Drug Reactions Associated With the Use of Hydroxychloroquine and Chloroquine During the COVID-19 Pandemic. Annals of Internal Medicine : 26 Jan 2021. Available from: URL:

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    Reported ADRs with chloroquine or hydroxychloroquine. Reactions Weekly 1841, 8 (2021).

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