Nigerian health officials are urgently warning people not to self-medicate with unproven treatments after three Nigerians overdosed on chloroquine, an anti-malarial drug U.S. President Donald Trump has repeatedly touted—without evidence—as a possible treatment for the novel coronavirus.

CNN reported Monday that "three people were hospitalized in the [Nigerian city of Lagos] after taking the drug."

"The Lagos State Health Ministry issued a brief statement saying there was no 'hard evidence that chloroquine is effective in prevention or management of coronavirus infection,'" CNN noted. "Chloroquine is used to treat malaria, lupus, and rheumatoid arthritis."

Despite warnings from health experts that chloroquine has not been tested for treating COVID-19, Trump falsely claimed during a press briefing Sunday that the evidence for chloroquine's effectiveness in treating the coronavirus is "very strong."

"Why should we be testing it in a test tube for a year and a half when we have thousands of people that are very sick, and we can use it on those people and maybe make them better?" the president asked.

Trump on using unproven and dangerous drugs for coronavirus: "Why should we be testing it in a test tube for a year and a half when we have thousands of people that are very sick, and we can use it on those people and maybe make them better?" pic.twitter.com/77gbCqFqg4 — Aaron Rupar (@atrupar) March 22, 2020

Sunday's briefing was not the first time Trump has peddled false or unproven claims about chloroquine's effectiveness in treating COVID-19.

"Now, a drug called chloroquine—and some people would add to it 'hydroxy-.' Hydroxychloroquine. So chloroquine or hydroxychloroquine. Now, this is a common malaria drug," Trump said during a briefing last Thursday. "The nice part is, it's been around for a long time, so we know that if it—if things don't go as planned, it's not going to kill anybody."

"There's tremendous promise," Trump contineud. "And normally the [Food and Drug Administration] would take a long time to approve something like that, and it's—it was approved very, very quickly and it's now approved, by prescription."

After president's remarks, the FDA issued a statement clarifying that it is "investigating" chloroquine as a possible coronavirus treatment but has not yet approved the drug for that purpose.

On Friday, the Nigeria Centre for Disease Control (NCDC) put out a tweet noting that the World Health Organization "has NOT approved the use of chloroquine for COVID-19 management."

"Scientists are working hard to confirm the safety of several drugs for this disease," NCDC added. "Please DO NOT engage in self-medication. This will cause harm and can lead to death."

According to Bloomberg, Nigeria reported two cases of chloroquine poisoning following Trump's Thursday briefing.

#FactsNotFear@WHO has NOT approved the use of chloroquine for #COVID19 management. Scientists are working hard to confirm the safety of several drugs for this disease. Please DO NOT engage in self-medication. This will cause harm and can lead to death.#COVID19Nigeria pic.twitter.com/K6kljq0VtW — NCDC (@NCDCgov) March 20, 2020

Ignoring warnings from medical professionals, Trump proceeded to double down on his claim about chloroquine's effectiveness in a pair of tweets on Saturday, declaring to his nearly 75 million Twitter followers that "HYDROXYCHLOROQUINE & AZITHROMYCIN, taken together, have a real chance to be one of the biggest game changers in the history of medicine."

HYDROXYCHLOROQUINE & AZITHROMYCIN, taken together, have a real chance to be one of the biggest game changers in the history of medicine. The FDA has moved mountains - Thank You! Hopefully they will BOTH (H works better with A, International Journal of Antimicrobial Agents)..... — Donald J. Trump (@realDonaldTrump) March 21, 2020 ....be put in use IMMEDIATELY. PEOPLE ARE DYING, MOVE FAST, and GOD BLESS EVERYONE! @US_FDA @SteveFDA @CDCgov @DHSgov — Donald J. Trump (@realDonaldTrump) March 21, 2020

"It only took a day for the president's tweets to get people hospitalized," lamented one Twitter user.

As ProPublica's Charles Ornstein reported Sunday, Trump's decision to boost chloroquine as a possible coronavirus treatment has "triggered a run on the drug" in the United States, causing a shortage of the medicine for those who need it to treat other serious conditions.

"Healthy people are stocking up just in case they come down with the disease," Ornstein reported. "That has left lupus patients... and those with rheumatoid arthritis suddenly confronting a lack of medication that safeguards them, and not only from the effects of those conditions. If they were required to take stronger drugs to suppress their immune systems, it could render them susceptible to more serious consequences should they get COVID-19."