What Is Ivermectin?
Ivermectin is a medication that treats some parasitic diseases. There are two types: one that doctors prescribe for certain health conditions in people and another that veterinarians prescribe, which is safe only for animals.
When ivermectin was first discovered in the 1970s, it was used only on animals because it kills some internal and external parasites that affect livestock as well as companion animals such as horses and dogs. Then in the 1980s, it was approved to treat some parasitic infections in people.
How Does Ivermectin Work?
Ivermectin is a type of anthelmintic, which is a medicine that kills parasites such as worms. It works by interfering with the nerve and muscle functions of parasitic worms. It paralyzes the parasites or inactivates their gut, which kills them.
Depending on the condition being treated, your doctor may prescribe ivermectin either in tablet form or topical form, such as a cream.
What Does Ivermectin Treat in Humans?
In people, the FDA has approved prescription ivermectin tablets to treat two infections caused by parasitic worms:
- Strongyloidiasis, which people usually get from contact with contaminated soil. It can cause problems such as belly pain, bloating, heartburn, diarrhea, and rashes. However, if you have strongyloidiasis, you may not have any symptoms.
- Onchocerciasis, which is spread through blackfly bites. Also called river blindness, this infection can bring on an itchy rash, vision loss, and abnormal growths under the skin.
Sometimes, doctors also prescribe a type of ivermectin that you put on your skin (called a topical medication) to treat head lice and skin conditions such as rosacea. For scabies, your doctor may prescribe either tablets or topical ivermectin.
Ivermectin for Animals
In animals, ivermectin can help prevent and treat parasites. It is used to treat gastrointestinal worms in horses, cattle, pigs, and other livestock, as well as lungworms, lice, mites, and grubs in certain animals. In dogs and cats, ivermectin is used to prevent heartworm.
Veterinary ivermectin comes in different formats, including a paste, pour-on liquid, injectable, and chewable. It’s dangerous for humans to take any drug made for animals, including ivermectin. A dose meant for a big animal such as a horse or cow (which can weigh 2,000 pounds or more) can be toxic or deadly for a person. Also, some inactive ingredients in ivermectin made for animals might not be safe for people.
Ivermectin for COVID-19
The FDA has not approved ivermectin to treat or prevent the illness caused by the coronavirus.
Through professional medical studies called clinical trials, scientists have been studying ivermectin to find out whether it can treat COVID. But according to the FDA, the data available from these clinical trials doesn’t show that ivermectin is effective against COVID. The FDA, CDC, Infectious Diseases Society of America, and World Health Organization say you shouldn’t take ivermectin for COVID unless you’re enrolled in one of these clinical trials.
The best way to protect yourself and your loved ones from the coronavirus is to get vaccinated. The COVID vaccines are approved for everyone aged 6 months and older. They’re generally safe and effective, with the benefits outweighing any risks.
The same can’t be said about taking ivermectin for COVID. If you’re not under a doctor’s care, it’s possible to take too much and overdose, which can lead to seizures, coma, and death.
People who have self-medicated with ivermectin made for animals have required medical attention, including hospitalization, according to the FDA. In July 2021, some poison control centers received five times as many calls about people experiencing side effects from taking ivermectin than they did before the pandemic.
Ivermectin Side Effects
At doses that doctors usually prescribe for people, ivermectin can have side effects such as:
- Constipation
- Diarrhea
- Headache
- Pain in your stomach
- Muscle pain or stiffness
- Difficulty moving
- Joint pain
- Reduced appetite
- Nausea or vomiting
- Tenderness in your neck, armpit, or groin
- Shaky movements (tremors)
Call your doctor right away if you’re taking prescription ivermectin and notice severe side effects such as:
- Any allergic reaction such as a rash, itching, hives, or swelling of your face, lips, or tongue
- Trouble breathing
- Vision changes
- Chest pain
- Fast, irregular heartbeat
- Confusion
- Eye pain, redness, or swelling
- Dizziness or fainting
- Fever
- Skin that gets red, blisters, peels, or loosens
- Seizures
- Peeing or pooping that you can’t control
- New swelling of the arms, feet, ankles, or lower legs
- Unusual tiredness or weakness
Ivermectin Dosage
Because overdosing on ivermectin is dangerous, it’s important to take it exactly as your doctor has directed. Don’t take more of it, and don’t take it more often than your doctor ordered.
The dose your doctor prescribes depends on the strength of the medicine, what you are taking it for, your body weight, and other factors. For example, if your doctor prescribes ivermectin to treat onchocerciasis and you weigh between 65 and 85 kg, your doctor may prescribe 4 tablets for you to take as a single dose.
If your doctor prescribes topical ivermectin, in the form of a lotion or cream, to treat conditions such as head lice or rosacea, the dose also depends on the strength of the medicine. So, be sure to use it as directed.
How Do You Take Ivermectin?
If your doctor recommends ivermectin tablets to treat a medical issue, make sure they know about any other health conditions you have. It’s especially important to tell them if you:
- Have asthma or liver disease
- Have had unusual or allergic reactions to foods, ingredients, or medicines
- Are pregnant, trying to conceive, or breastfeeding
Also, let them know about any other medications or supplements you’re taking. Ivermectin can mix badly with certain meds, such as blood-thinning drugs.
Swallow the correct dose with a glass of water on an empty stomach at least 30 minutes before or 2 hours after you eat. Don’t take ivermectin with food.
Take the full course of medicine as prescribed, even if you start feeling better before you finish taking it. If you miss a dose, take it as soon as possible. If it’s almost time for you to take your next dose, take that dose alone; don’t take double the amount.
Takeaways
Ivermectin is used to treat parasitic infections in both people and animals, but the type given to animals is unsafe for people. Although people believe it may help treat COVID, the FDA has not approved it for that purpose. Your doctor may prescribe ivermectin to treat infections such as strongyloidiasis and head lice, and it may be in the form of a tablet or a topical cream. It’s important to take ivermectin as your doctor has directed.
Ivermectin FAQs
How long until ivermectin starts to work?
How long it takes for ivermectin to work depends on what you’re taking it for. If your doctor has prescribed topical ivermectin to treat head lice, it can kill the lice right away after it’s applied. But if you’re taking ivermectin to treat onchocerciasis, it's a long-term treatment, given every 6 months.
How long does ivermectin stay in your system?
Ivermectin stays in your system for about 12 days.
Does ivermectin kill scabies immediately?
To treat scabies, your doctor may prescribe ivermectin in different formats and doses, which may stretch over multiple days. So, ivermectin may not kill scabies in one dose.
What is ivermectin made from?
Ivermectin was developed from a microorganism that was discovered in a soil sample in Japan in the 1970s.
What are some of the over-the-counter (OTC) human parasite medications?
Some medications to treat parasitic infections in humans are available OTC, and others require a prescription. Certain forms of ivermectin, such as a topical treatment for head lice, are available OTC to treat parasites.