You’ve probably heard of ivermectin, a drug best known for getting rid of parasites in animals and humans. Like other pandemic-related topics, this once-obscure drug has catapulted into the global discussion because…well, people are desperate for treatments that work against COVID.
While some research in 2020 suggested ivermectin might be useful against COVID, those results haven’t stood up under scientific scrutiny, said Dr. Joseph Khabbaza, a pulmonary and critical care physician at the Cleveland Clinic in Ohio.
Early studies were conducted in laboratory culture dishes when scientists were testing pretty much anything and everything against the COVID-causing virus, SARS-CoV-2. However, just because a drug can kill a virus in a lab dish doesn’t make it a safe or effective treatment in humans, he said.
Some research was “very flawed or even fraudulent,” Khabbaza noted. “Those have been debunked; all the really good studies have not shown a benefit.” (Here’s an in-depth look at one prominent ivermectin study with serious flaws and inconsistencies.)
The verdict so far is clear: Ivermectin, although it’s still being studied, “has not been found to be effective for the prevention of COVID-19 or the treatment of acute infection once it has developed,” Khabbaza said.
Even one of the drug’s main manufacturers, Merck, said in a Feb. 4 statement that there’s “no meaningful evidence” to suggest ivermectin works to treat or prevent COVID, and that there’s been “a concerning lack of safety data in the majority of studies.”
However, people have become so convinced that ivermectin is a cheap and readily available “cure” for COVID, they continue to take it against all medical advice and common sense.
People haven’t opted for this debunked treatment strategy on their own. COVID misinformation can be found just about everywhere, especially on Facebook, Instagram, and YouTube. The use of ivermectin has been recommended by doctors who promote bogus cures and vaccine misinformation, and podcast host Joe Rogan, who has millions of listeners, said he took the drug for COVID, among other treatments.
US prescriptions for ivermectin increased at least 24-fold in 2021, going from 3,600 prescriptions a week before the pandemic to 88,000 prescriptions a week in August, according to the Centers for Disease Control and Prevention. That’s just retail pharmacies and oral forms of the drug. Those numbers don’t include mail orders, skin preparations, or veterinary forms of ivermectin.
People have swallowed potentially toxic and lethal doses of the drug meant to be injected in or poured on cows, sheep, or horses. The Food and Drug Administration even had a tweet go viral in August when it pointed out that people aren’t farm animals.
So many people got sick from the drug that calls to poison control centers regarding ivermectin increased fivefold in July compared with prepandemic levels, according to the CDC, and New Mexico public health officials reported two possible deaths linked to the drug.
Due to the demand, people who need ivermectin to treat farm animals have found it’s in short supply or being sold on Amazon at price-gouging levels.
Developed in the 1970s, ivermectin is sold under the brand names Stromectol, Soolantra, and Sklice. It’s an anthelmintic drug, which means it fights parasites. It can be found in heartworm medications for dogs, for instance.
Heartworms are footlong and potentially life-threatening parasites spread by mosquitoes that can invade the heart, lungs, and blood vessels of dogs, cats, ferrets, and other animals.
For humans, ivermectin is sold in tablets or lotions to treat rosacea, a condition that can cause facial redness; scabies, which are microscopic, itchy mites that are sometimes sexually transmitted; and head lice.
It’s also a crucial drug for treating or preventing parasitic worms in humans, including onchocerciasis, or river blindness, a devastating infection spread by blackflies that can cause severe itching, disfiguring skin changes, and permanent vision loss.
Millions of people take ivermectin at least once or twice a year to fight the parasite, a strategy that has helped eliminate it in Colombia, Ecuador, Mexico, and Guatemala. Almost all cases are now in 31 countries in sub-Saharan Africa. More than 145 million people were treated in Africa in 2017 according to the World Health Organization.
“Ivermectin is a very important medication from a worldwide standpoint,” said Dr. Scott Weisenberg, an infectious diseases specialist and associate professor of medicine at NYU Langone in New York.
However, just because a drug is effective against one type of organism — a parasite — doesn’t mean it works against other ones, like the virus that causes COVID.
“Things that kill viruses don’t kill bacteria, things that kill bacteria don’t kill worms, things that kill worms don’t wind up killing viruses,” said Arthur Caplan, director of medical ethics at the NYU Grossman School of Medicine.
What are the side effects of ivermectin?
Even though all medications have a potential for side effects, the risks of taking a parasite-killing drug may be higher than others, said Dr. Waleed Javaid, epidemiologist and director of Infection Prevention and Control at Mount Sinai Downtown in New York.
“These drugs are not nontoxic,” he said. “Parasites are big organisms, they are not microscopic. You can see them — they are big worms in the belly — so just thinking about them, the drugs that affect them have to be more toxic than drugs that affect bacteria and viruses, which are much smaller. The bigger the organism you want to kill, usually you need to escalate the dose and the toxicity.”
Any drug taken at the incorrect dose or formulation can be ineffective or even dangerous. That’s why taking ivermectin intended for farm animals — like cattle, which can weigh 1,500 pounds or more — can be especially harmful.
According to the CDC, at least one person has tried to prevent COVID by drinking a type of ivermectin meant to be injected into cattle. They ended up with confusion, hallucinations, shortness of breath, tremors, and drowsiness.
“The patient recovered after being hospitalized for nine days,” the CDC reported.
Another person who already had COVID took ivermectin tablets they bought on the internet and had an “altered mental status” and couldn’t really answer questions or follow commands. They improved after they were hospitalized and stopped taking ivermectin, according to the CDC.
When taken at the low doses and for conditions that are known to respond to the drug, there may be relatively few or mild side effects, like nausea, rash, or itchy skin, said Khabbaza.
However at high doses, side effects “can get really profound,” he said.
The following side effects and drug interactions that can occur with ivermectin are signs of ivermectin toxicity, according to the CDC:
Abdominal pain, nausea, vomiting, and diarrheaDizzinessLow blood pressureTachycardia (an abnormally fast heart rate)HeadacheBlurred vision and visual hallucinationsConfusionTremors and loss of coordination and balanceSeizuresCentral nervous system depression, decreased alertness, and coma
Ivermectin can also be dangerous when mixed with drugs that also can suppress the central nervous system, like benzodiazepines and barbiturates. It can sometimes increase the risk of side effects in people taking the blood-thinning drug warfarin.
The CDC recommends calling the poison control hotline (1-800-222-1222) and seeking immediate medical treatment if you have taken ivermectin and are experiencing symptoms.
Treatments that actually work for COVID
There are other treatments that can help hospitalized patients who have COVID, said Khabbaza. Some are low- or no-cost, including the steroid drug dexamethasone, which is used in severe, late-stage COVID to help suppress the immune system overreaction known as a cytokine storm.
Additional COVID treatments are the antiviral drug remdesivir, which is also used only in people sick enough to be hospitalized, and monoclonal antibodies, which can help mild or moderate cases. Monoclonal antibodies can also be used to help prevent infection in people who have been exposed to the virus and are at high risk of hospitalization or death. However, it’s not a substitute for vaccination.
The best way to prevent or reduce your risk of COVID is still to get vaccinated, said Khabbaza.
“Really there are a handful of things that have been shown to be a little bit helpful but nothing has been shown to be the game changer we hoped,” said Khabbaza. Vaccines are “ certainly your best weapon and always have been to avoid getting infected.”
Medical experts emphasize that there is no reason to think ivermectin actually is some unrecognized wonder drug and there’s a conspiracy to keep people from an effective treatment.
“The most important fact to me is the manufacturer says don’t use it — the people who are going to make money from it are saying they don’t want you to take that drug,” said Caplan. “That to me is as loud a message as you can get. I have this drug, I can sell it to literally tens of million people if it works, but it doesn’t work — so don’t use it.” ●