People in Nigeria are poisoning themselves with chloroquine after President Donald Trump spent last week boosting it as an unproven cure for coronavirus.

The Nigerian Center for Disease Control had to issue a warning late last week to remind people that the World Health Organization had “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,” the center added in a tweet.

Dr. Oreoluwa Finnih, a senior special assistant on health at the Lagos State government said hospitals in the Nigerian capital were now reporting admissions from people suspected of having chloroquine poisoning, though he didn’t give exact numbers.

Last Thursday Trump touted the malaria drug as a “game-changer” in the fight against coronavirus, even though Dr. Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases who has been leading government efforts to fight the disease, warned against calling the drug “fairly effective” because it hasn’t been tested in a clinical trial as a treatment for COVID-19.

But Trump dismissed Fauci’s concerns and over the weekend continued to push chloroquine as a cure.

“This would be a gift from heaven. This would be a gift from God if it works. So we’re gonna pray to God that it does work,” Trump said at a press conference on Saturday, adding that his administration plans to ship 10,000 doses of it to New York state to test it out.

He also tweeted about the drug over the weekend.

The Food and Drug Administration (FDA) has pushed back against Trump’s claims about chloroquine. The commissioner of the FDA, Stephen Hahn, contradicted the president, saying chloroquine “was undergoing clinical testing in order to gauge its effectiveness.”

But the impact of Trump boosting the unproven drug was instant.

“The pharmacist knew the market and was saying to every incoming customer: ‘You know Donald Trump has said this thing cures coronavirus,’ and the price kept changing,” Kayode Fabunmi, a lawyer in Lagos, told CNN. “The original price was 200 naira (around 50 cents), then it became 500 naira ($1.38) then it became 1,000 naira ($2.77) while I was there.”

Chloroquine has been around for decades and was primarily used in the treatment of malaria. But it is also used to treat lupus and rheumatoid arthritis, and some U.S. patients are now concerned about widespread shortages of the drug after hospitals bought up all available supplies in recent days.

However, in Africa, where it was widely used to treat malaria, the drug has been phased out by 40 countries — including Nigeria — because the malaria parasites have built up a resistance to chloroquine.

Despite the use of other drugs to treat malaria, many Africans continue to use tablets containing chloroquine and it is still widely available from pharmacies.