Intended for healthcare professionals

Letters Covid-19: Molnupiravir effects

Buyer beware: molnupiravir may damage DNA

BMJ 2021; 375 doi: (Published 04 November 2021) Cite this as: BMJ 2021;375:n2663
  1. Johan M van Schalkwyk, perioperative physician
  1. Auckland District Health Board, Auckland City Hospital, Auckland, New Zealand
  1. johanvs{at}

Although the Ingelfinger rule seems to have dissolved into dust with the coming of covid-19,1 I was a little disappointed that your journal seems to have mirrored Merck’s press release about molnupiravir without substantial critical comment.2

Molnupiravir clearly induces intense mutagenesis in SARS-CoV-2,3 and this accounts for its efficacy. But β-d-N4-hydroxycytidine, the active metabolite of molnupiravir, is not only cytotoxic but also mutagenic in mammalian cells.4 The drug may damage DNA.

There is a certain irony that vaccine shy people who have believed the untruth that vaccines against SARS-CoV-2 alter DNA seem poised to reach for a perceived “alternative” that may actually alter their DNA adversely. This worry is supported by the rise in Merck’s share price and Moderna’s corresponding drop, as reported by Reuters.5

Buyer beware.


  • Competing interests: None declared.

This article is made freely available for use in accordance with BMJ's website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.


View Abstract