Oleandrin (Oleander) and Covid-19August 24, 2020 Oleandrin has been found to have antiviral activity in a test tube, just like many chemicals. It should not be used as a home remedy for COVID-19. Call poison control at 1-800-222-1222 if you or somebody you are with has symptoms from Oleandrin and toxicity which can include nausea, headache, vomiting, irregular heartbeat and diarrhea.