Skip to main content

COVID-19 comment: 'Poisonous' Chloroquine has no evidence for treating Covid-19 yet – University of Reading

Show access keys

COVID-19 comment: 'Poisonous' Chloroquine has no evidence for treating Covid-19 yet

Release Date 23 March 2020

COVID-19 expert comment

Professor Parastou Donyai, from the School of Pharmacy at the University of Reading, said:

"Chloroquine has been around for more than 80 years. Developed as an anti-malarial drug, chloroquine is now used for other conditions including rheumatoid arthritis, and systemic and discoid lupus erythematosus. Chloroquine was manufactured to provide an alternative to the natural substance quinine, which is found in the bark of Cinchona trees and was previously used to treat malaria.

"Although it was used to treat malaria for many years, chloroquine has stopped working against some forms of malaria in many countries around the world, and where it is used, chloroquine is combined with other antimalarials. This problem of chloroquine resistance includes Nigeria, where chloroquine shouldn’t be used anymore.

"But over the weekend there were new reports of chloroquine poisoning. Why? It seems that some people are taking chloroquine, without medical advice, on hearing rumours that it might treat COVID-19. But chloroquine is not proven to work against COVID-19. Importantly, taking chloroquine for COVID-19 without medical advice is really dangerous.

"Chloroquine works against malaria by going into red blood cells. It also goes into the liver, spleen, kidney, heart, and parts of the eye (cornea and retina). Although chloroquine is an old drug and is related to a ‘natural’ source, it is far from safe if used without advice.

"Firstly, it’s really easy to get the dose of chloroquine wrong and end up with too much of it in the body. Too much chloroquine is poisonous: at first you feel sick, get stomach-ache, vomit, feel sleepy and start shaking. But soon, your breathing can stop, your heart too, and you could slip into a coma. Patients can die very quickly from chloroquine poisoning. 

"Secondly, it takes the body a really long time to flush all of the chloroquine out. So, if you take chloroquine, even at a correct dose for a long time, you might find that it still damages your body. Chloroquine is especially harmful to the eyes, and no one should be taking it without regular eye checks. 

"COVID-19 affects the lung and the airways with the main signs being fever, a persistent cough and shortness of breath or breathing difficulties. In some people the illness can lead to pneumonia, severe acute respiratory syndrome, kidney failure and even death. There is currently no known cure for COVID-19.

"So, people are naturally worried and want to be able to protect themselves against a scary illness. But there has been a lot of confusion about chloroquine and COVID-19, especially in some African countries where chloroquine is readily-available. Stories about chloroquine and COVID-19 spiralled out of control when President Trump announced, wrongly, that the US Food and Drug Administration was soon to approve the drug for COVID-19.

"The science around chloroquine and COVID-19 is unclear. It is certainly true that doctors and scientists are looking into whether chloroquine (and a related drug called hydroxychloroquine) works against COVID-19. For example, both drugs have been tested in the lab and in some patients. However, none of the studies so far show convincingly that chloroquine or hydroxychloroquine work against COVID-19.

"The current trials are not finished. In any case, if either of these drugs is found to be useful for COVID-19, it would need to be given by doctors monitoring patients closely to prevent poisoning. No one should be buying and taking chloroquine or hydroxychloroquine for COVID-19. There is no proof that chloroquine or hydroxychloroquine will help them but plenty of data to show that it can harm them."


We use Javascript to improve your experience on, but it looks like yours is turned off. Everything will still work, but it is even more beautiful with Javascript in action. Find out more about why and how to turn it back on here.
We also use cookies to improve your time on the site, for more information please see our cookie policy.