Editor’s Note: We made changes for accuracy, style, and formatting. This article reflects the information and research available at the time of its original publication on March 6, 2020.
Key Takeaways
- Schweppes and Canada Dry tonic water do not contain chloroquine. Tonic water contains quinine, which is a different compound.
- Chloroquine showed activity against SARS-CoV-2 in laboratory experiments, but this did not prove that it could successfully treat COVID-19 patients.
- Clinical evidence remained preliminary in early March 2020. Chloroquine should not be considered a proven COVID-19 treatment or used without appropriate medical supervision.
Scientists Investigate Chloroquine for COVID-19
Tonic water contains quinine, not chloroquine, and there was no evidence in March 2020 that drinking tonic water could prevent or treat COVID-19.
As the new coronavirus spreads internationally, researchers are investigating existing medications that might be useful against COVID-19. One drug attracting considerable attention is chloroquine, an older medication used to prevent and treat malaria and for certain autoimmune conditions.
Early laboratory research has produced promising results, but as of March 2020 there is not enough clinical evidence to establish chloroquine as a safe and effective treatment for COVID-19.
Researchers in China and other countries are therefore investigating the drug in patients.
Chloroquine Shows Activity in Laboratory Studies
Interest in chloroquine is partly based on earlier research involving SARS-CoV, the coronavirus responsible for the 2003 SARS outbreak.
In a 2005 laboratory study, researchers found that chloroquine inhibited SARS-CoV infection and spread in cultured cells. These findings suggested that chloroquine had antiviral properties worth investigating, but they did not demonstrate that the medication could successfully treat coronavirus infections in people.
More recently, researchers tested chloroquine against SARS-CoV-2, the virus responsible for COVID-19. A February 2020 study published in Cell Research found that chloroquine inhibited SARS-CoV-2 infection in cultured cells.
The researchers concluded that chloroquine and the experimental antiviral remdesivir deserved further assessment in patients with COVID-19.
However, results obtained in cultured cells do not necessarily translate into an effective treatment in humans. Clinical trials are required to determine whether chloroquine is both safe and effective for people with COVID-19.
Early Reports From China
Chinese researchers have also reported preliminary observations from clinical studies involving chloroquine phosphate.
A February 2020 report in BioScience Trends stated that chloroquine had shown apparent benefit in Chinese clinical studies involving patients with COVID-19-associated pneumonia. The authors reported that the drug was being considered for inclusion in Chinese treatment guidelines.
These reports generated considerable interest, but detailed results from large randomized controlled trials were not yet available. Claims that chloroquine improves recovery, reduces fever, or shortens hospital stays should therefore be regarded as preliminary rather than established medical evidence.
At this stage, chloroquine remains an experimental treatment for COVID-19 rather than a proven cure.
What About Quinine in Tonic Water?
Chloroquine and quinine are related historically through their use against malaria, but they are different compounds.
Tonic water contains small amounts of quinine, which gives beverages such as Schweppes and Canada Dry tonic water their characteristic bitter taste. It does not contain chloroquine.
There is also no evidence that drinking tonic water can prevent or treat COVID-19. The presence of quinine in a beverage should not be interpreted as providing the same effects as a prescription antimalarial medication.
People should not use tonic water as a treatment for COVID-19 or attempt to self-medicate with chloroquine.
Other Drugs Under Investigation
Researchers are examining several existing and experimental medications to determine whether they could be repurposed against COVID-19.
One of the most closely watched is remdesivir, an experimental antiviral previously investigated for Ebola. Laboratory research published in February 2020 found that both remdesivir and chloroquine inhibited SARS-CoV-2 in cultured cells.
Other antiviral medications are also under investigation. However, laboratory activity and preliminary clinical reports are only the first steps in determining whether a medication actually benefits patients.
Final Thoughts
Chloroquine was a promising subject of COVID-19 research in early 2020 because laboratory studies showed antiviral activity and preliminary reports from China suggested possible clinical benefits. However, those findings were not sufficient to establish the drug as an effective COVID-19 treatment.
Most importantly, tonic water is not an alternative to chloroquine. Schweppes, Canada Dry, and other tonic waters contain quinine rather than chloroquine, and there is no evidence that drinking tonic water can prevent or treat COVID-19.
References
Gao, J., Tian, Z., & Yang, X. (2020). Breakthrough: Chloroquine phosphate has shown apparent efficacy in treatment of COVID-19 associated pneumonia in clinical studies. BioScience Trends, 14(1), 72–73. https://doi.org/10.5582/bst.2020.01047
Vincent, M. J., Bergeron, E., Benjannet, S., Erickson, B. R., Rollin, P. E., Ksiazek, T. G., Seidah, N. G., & Nichol, S. T. (2005). Chloroquine is a potent inhibitor of SARS coronavirus infection and spread. Virology Journal, 2, 69. https://doi.org/10.1186/1743-422X-2-69
Wang, M., Cao, R., Zhang, L., Yang, X., Liu, J., Xu, M., Shi, Z., Hu, Z., Zhong, W., & Xiao, G. (2020). Remdesivir and chloroquine effectively inhibit the recently emerged novel coronavirus (2019-nCoV) in vitro. Cell Research, 30(3), 269–271. https://doi.org/10.1038/s41422-020-0282-0