SINGAPORE - Ivermectin, an anti-parasitic drug, has lately come under intense scrutiny as part of a government clampdown on its illegal distribution and false claims surrounding the pill as a cure for Covid-19.

Poisoning from taking the pill has risen sharply in the United States this year, where many had taken the pills believing the drug could treat Covid-19.

The US National Poison Data System received 1,718 ivermectin exposure cases reported for the year till Oct 17 - more than double the numbers for the same period during the previous year.

In Singapore, a 65-year-old woman was hospitalised on Oct 1, suffering from fever, joint inflammation and vomiting after taking ivermectin pills on the advice of friends.

How did ivermectin grow in prominence in the first place and can it protect people from the coronavirus? The Straits Times answers your questions.

Q: What is ivermectin?

A: Ivermectin is an anti-parasitic drug used to treat some parasitic infections. In Singapore, it is not available from consumer shelves and can be issued only by medical professionals, who often use it to treat parasite infestations, like scabies or head lice.

It was first developed in the US in the 1970s by scientists on a mission to stop parasitic infections and used in farms to deworm horses and other animals.

In 1996, it was approved by the US Food and Drug Administration (FDA) for use in humans. It was famously used to treat river blindness in Latin American countries and later repurposed to treat parasite infestations and even malaria.

Q: Why do people think that ivermectin can cure Covid-19?

A: Ivermectin was one of many drugs studied when scientists were looking to find safe generic drugs that could be repurposed for Covid-19 treatment.

One of the earliest studies, published in June 2020 by the National Centre for Biotechnology Information in the US, showed that high doses of ivermectin could subdue the coronavirus responsible for Covid-19 in vitro.

The results have not yet been proven in animals or humans, but many people latched on to the hope that it was the cure humanity sought.

There are many studies under way to test ivermectin's efficacy in treating Covid-19.

Q: What are the authorities saying about ivermectin?

A: Studies on the use of ivermectin to treat Covid-19 are under way but the authorities, such as the World Health Organisation, have reiterated that current data does not prove that the drug is effective.

Merck, a manufacturer of ivermectin pills, has also advised against the use of the drug to treat Covid-19.

Associate Professor Jenny Low, a senior consultant of infectious diseases from the Singapore General Hospital, told ST that while the evidence does not rule out ivermectin as a potential cure, there is still no strong evidence to support it.

The Ministry of Health (MOH) said in a statement on Sunday (Oct 24): "Ivermectin is a prescription-only medicine registered in Singapore specifically for the treatment of parasitic worm infections. It is not an anti-viral medicine and is not approved by the Health Sciences Authority (HSA) for preventing or treating Covid-19."

Q: What are the dangers of taking ivermectin?

A: Ill-advised consumption of ivermectin can cause toxic effects such as seizures and liver injury, according to the New England Journal of Medicine, a peer-reviewed publication from the Massachusetts Medical Society.

The FDA cautioned against the use of ivermectin, especially for those taking other medications like blood-thinners. Large doses of the drug can be highly toxic, it said, addressing misinformation that the pills can be taken in large quantities.

Q: What about the studies that claim it's fit for treating Covid-19?

A: Prof Low said much of the controversy over ivermectin stems from the fact that its proponents have ignored the varying quality of trials testing the drug's use for Covid-19.

The doses that showed the drug to work in the laboratory do not translate to humans, as the dosage tested is several hundred times higher than what is recommended for humans, she added.

Q: My friends are supplying ivermectin. Should I buy from them?

A: In Singapore, it is illegal to self-medicate with ivermectin, which can be prescribed only by a doctor.

The HSA is currently investigating the illegal sale and supply of ivermectin linked to the incident of the 65-year-old woman, who is said to have bought the drug through a friend. ST has contacted MOH for case figures of ivermectin exposure in Singapore.

Those found guilty of illegally selling medicines can get into trouble with the law.

Those who spread false claims about the virus may also face penalties.

Criminal lawyer James Ow Yong of Kalco Law told ST that those who give advice without basis may be found guilty of causing hurt by a rash or negligent act under the Penal Code.

On Sunday, Singapore's fake news law was invoked against local website Truth Warriors for its false claims about the safety of ivermectin in treating Covid-19.