Last week there were reports that oleandrin, a highly toxic plant chemical, had been discussed in the White House as a potential treatment for COVID-19.

Oleandrin is a chemical found in oleander – an ornamental flowering shrub or small tree. It is a cardiac (heart) glycoside, a chemical which can increase the speed and force of heart contractions. This property has been harnessed in the drug digoxin, a similar chemical which is derived from the foxglove plant. Digoxin is a licensed medicine which is still occasionally used in the treatment of heart rhythm problems and heart failure. However, people taking it need to be very closely monitored by their doctors, as it can cause toxic and potentially fatal adverse effects.

The news follows a study showing that the oleandrin killed the SARS-Cov2 virus in the laboratory. However, its impact on the virus has not yet been tested in animals, much less in humans. Oleandrin is not currently licensed to treat any medical condition. There have been past reports of poisoning and death among people who have ingested oleander leaves or extracts.

The toxic nature of this chemical means that no one should consider self-medicating using any part of the oleander plant or any extract made from it to prevent COVID-19, or for any other reason.

Where did the story come from?

MedpageToday, ABC News and The Conversation are among several media sources to report on oleandrin, a recent study of its effects on the novel coronavirus, and the reported discussion of it in the White House. The laboratory study in question was published on the preprint server bioRxiv and has not been through peer-review by other experts in the field, meaning that its findings should be viewed with caution.

What is the basis for the claim?

Oleander extract containing oleandrin has been tested for anti-cancer effects in the laboratory and some very small, early stage studies in humans. More recently oleandrin had also been shown to have anti-viral effects in the laboratory.

So, researchers at the University of Texas, and the company that has been developing oleandrin for use as a drug (Phoenix Biotechnology, Inc.) wanted to study whether it might have an impact on SARS-CoV-2, the virus that causes COVID-19.

In their current laboratory study the researchers added very low doses of oleandrin to monkey kidney cells either before or after they were exposed to SARS-CoV-2. The researchers found that oleandrin could reduce the amount of virus produced by the infected cells over 48 hours (even at the low doses used oleandrin did also kill some of the cells).

This is very early stage research and oleandrin has not been tested in animals or humans exposed to
SARS-CoV-2, so there is no evidence that it would have a beneficial impact and be safe for such use.

Experts have highlighted concerns about the lack of evidence. A professor in preventive medicine and infectious disease from Vanderbilt University Medical Centre stated: “What happens in test tubes is one thing, what happens in people is another”. Another doctor from Sunnybrook Health Sciences Centre in Toronto said the extract “would definitely end up killing people.”

Other experts highlight case reports of poisoning in people who had ingested the plant or extract. For example, one study reported on two people hospitalised after consuming snails thought to have eaten the plant; another involved a young woman who had taken an oleander extract. All cases became seriously unwell with nausea, vomiting and irregular heart rhythms – which are known toxic effects of cardiac glycosides.

What do trusted sources say?

The US Food and Drug Administration is said to have declined to comment on oleandrin telling ABC News “per policy, the FDA does not comment on, confirm or deny potential product applications.”

The WHO does not comment on oleandrin specifically, but their general advice is: “While some western, traditional or home remedies may provide comfort and alleviate symptoms of mild COVID-19, there are no medicines that have been shown to prevent or cure the disease. WHO does not recommend self-medication with any medicines, including antibiotics, as a prevention or cure for COVID-19.”

The Memorial Sloan Kettering Cancer Centre’s page on oleandrin highlights its potential risks and says that it should not be used outside of clinical trials.


Analysis by EIU Healthcare, supported by Reckitt Benckiser



  1. Plante KS et al. Prophylactic and Therapeutic Inhibition of In Vitro SARS-CoV-2 Replication by Oleandrin. bioRxiv. 2020 Jan

Reading list

  1. WHO. Q&A on coronaviruses (COVID-19) Updated 17 April 2020
  2. Memorial Sloan Kettering Cancer Center. Oleandrin. Updated 19 August 2020