[Tonic water and quinine-a bicentennial booming cocktail]

During the SARS-CoV-2 pandemic, the media has often mentioned the presence of quinine in tonic water. Media accounts of quinine's antiviral effect in vitro, as well as press reports about quinine-based compounds, such as hydroxychloroquine, have sparked renewed public interest in drinking tonic water, which could perhaps result in an increase in allergic phenomena. On the 200th anniversary of the discovery of quinine, our main objective was to analyze hypersensitivity reactions, related to the consumption of beverages containing quinine, described in the literature.

We analyzed case reports indexed on Pubmed, Scopus, and Google Scholar. A quinine causality score was calculated for each of the observations. A quinine assay was performed on several beverages for which the quinine content had not been published.

In parallel with related pharmacokinetic studies, these case reports consist of 26 observations. The case reports mainly related to young men, with symptoms of varying severity, mainly dermatological, with fixed drug eruption, generalized rashes, hives; hematological, with thrombocytopenia, hemorrhagic syndrome, thrombotic microangiopathy; more rarely ocular, cardiac or auditory. The level of causality of quinine is certain for three cases, probable for twenty-two, possible for two. The levels of quinine, all conforming to the standards, were lower in the spirits and the cooked wine than those of tonic water.

Possibly under-diagnosed, the main mechanism of these reactions is immuno-allergic, without any cross-reaction with other quinolines having been shown. In these patients and breastfeeding women of G6PD deficient newborns, any medicines, phytotherapy, homeopathy, or even cosmetics containing quinine, on the basis of a proposed list, should be avoided.