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What is ivermectin?

Ivermectin is an FDA-approved antiparasitic drug. It treats internal parasitic infections, like intestinal strongyloidiasis, onchocerciasis (river blindness), and other infections caused by parasitic worms, like hookworm, roundworm, and whipworm.

The oral tablet formulation is also sold under the brand name Stromectol in the US.

What is ivermectin used to treat?

Oral ivermectin treats the following conditions:

  • Hookworm infections, like filariasis

  • Whipworm infections, like trichuriasis

  • Roundworm infections, like ascariasis and intestinal strongyloidiasis

  • Onchocerciasis

  • Scabies

  • Other parasitic worm infections

Ivermectin binds to various parts inside parasitic worms and interferes with their muscle and nerve functions, causing paralysis, starvation, and death. Ivermectin also stops adult parasitic worms from making larvae.

Scabies is a parasitic infestation of the skin that is very common in tropical areas. A study on the treatment of scabies with ivermectin found that a single dose of the medication was effective enough to treat healthy patients and many patients with HIV infection.¹

Topical (cream and lotion) forms of ivermectin treat the following conditions:

The FDA does not approve the use of ivermectin for the treatment of COVID-19

While one type of this medicine is strictly used to treat parasitic infections in humans only, veterinarians use another type of ivermectin medicine to treat animals. The two types of drugs are not interchangeable.

How do you take ivermectin?

Ivermectin is available in topical forms (creams and lotions) to treat skin conditions, like rosacea, and external parasites, like head lice.

Ivermectin is also available as a tablet to take orally (by mouth). Take the tablet on an empty stomach (at least 30 minutes before or two hours after food) with a glass of water.

Ivermectin is usually taken in one dose. However, there are certain instances when your doctor might prescribe additional doses. For example, to treat onchocerciasis, your doctor might prescribe additional doses at three, six, and 12 months to eliminate the infection.

Always take ivermectin as directed by your doctor. Make sure you do not take less or more than what is prescribed.

Do not share your prescription drug with anyone else — the dosage is prescribed according to your weight, your medical history, the condition being treated, and your response to treatment.

Seeing results

Your doctor might order some lab tests periodically to check your body’s response to the treatment and ensure the infection clears. Some tests you might have to undergo include the following:

  • Stool exams to detect intestinal parasites

  • Thorough physical exams and eye exams at regular intervals if you suffer from river blindness

If the infection has not cleared, your doctor might prescribe an extra dose of ivermectin.

Who should not take ivermectin?

Although ivermectin is relatively safe and effective in treating several parasitic infections, it might not be suitable for people with certain medical conditions. Please let your doctor know if you have any of the following conditions:

  • Asthma — the medication could worsen your asthma

  • Liver problems —the drug can further harm your liver or cause other side effects

  • Seizures — since ivermectin can cause seizures, ask your doctor if it is safe for you to take

  • HIV — this condition makes infections harder to treat, so you might require more doses of ivermectin to treat a parasitic infection

Other groups of people who might be at risk when taking ivermectin include the following:

  • Pregnant people — there is a lack of sufficient studies on the safety of ivermectin use during pregnancy

  • People who are breastfeeding — ivermectin can pass to the baby through breast milk

  • Older adults — the drug can stay in your body for longer and increase your risk of side effects

  • Children weighing less than 33 pounds — studies have not been conducted on the safety of ivermectin in children weighing less than 33 pounds

Potential side effects of ivermectin

Ivermectin is a relatively safe drug when used under strict medical supervision. However, using this medication may cause you to experience one or more side effects. The side effects experienced often depend on the medical condition being treated.

The following side effects may occur with ivermectin oral tablets.

Mild side effects usually disappear within a few days of taking ivermectin. Contact your doctor immediately if you experience one or more side effects that persist or become severe.

Common side effects when used to treat intestinal parasites

  • Stomach pain

  • Tiredness

  • Loss of energy

  • Diarrhea

  • Constipation

  • Dizziness

  • Drowsiness

  • Nausea

  • Vomiting

  • Loss of appetite

  • Itchiness

Common side effects when used to treat eye or skin infections

  • Itching

  • Rash

  • Eye problems

  • Swollen and painful lymph nodes in the groin, armpits, or neck

  • Swollen or painful joints

  • Pain or stiffness in the muscles

  • Fever

Serious side effects

Ivermectin rarely causes severe side effects. Visit the nearest emergency room immediately or call your doctor for advice if you notice any of the following:

  • Swelling in the arms, feet, hands, or face

  • Pain in the neck and/or back

  • Loss of control of bowel movements or urination

  • Chest pain

  • Fast heartbeat

  • Seizures

  • Confusion

  • Disorientation

  • Loss of consciousness

  • Difficulty breathing

  • Changes in vision or loss of vision

  • Swelling, redness, or pain in the eyes

  • Redness or peeling of the skin

  • Skin blisters

  • Unusual weakness or tiredness

A single tablet of ivermectin is often enough to treat most parasitic infections. After reviewing your condition, your doctor might prescribe additional doses if your infection has not cleared up.

Taking more medication and for a more extended period than prescribed may lead to ivermectin toxicity symptoms. These may include the following:

  • Gastrointestinal problems, like abdominal pain, nausea, vomiting, and diarrhea

  • Headaches

  • Blurred vision

  • Low blood pressure (hypotension)

  • Fast heart rate (tachycardia)

  • Visual hallucinations

  • Confusion

  • Altered mental status

  • Loss of balance and coordination

  • Seizures

  • Central nervous system (CNS) depression


You are unlikely to accidentally overdose on ivermectin because you will take this drug as a single dose in most cases. However, a mild overdose can occur if your prescribed dose is too high.

Intentional ivermectin overdose can cause extremely serious symptoms. If you suspect you or someone else has taken too much ivermectin, please call 911. You can also seek immediate medical advice by calling the poison control center hotline (1-800-222-1222).

What to discuss with your doctor before starting ivermectin

Before taking ivermectin, discussing your current medical history with your doctor is essential. Some important information to share with them includes the following:

  • Any known drug allergies

  • Medications you are currently taking

  • Your current medical history and any medical conditions you have

You might have several questions for your doctor about taking this drug. Some questions to ask before starting treatment include:

  • How should I use the medication?

  • What precautions must I take when taking the medication?

  • How long will it be before I notice results?

  • What side effects can I expect when taking this medication, and how should I deal with them?

  • How do I store and dispose of the medication?

Stopping ivermectin

Ivermectin is often prescribed as a single dose, so there are no reactions associated with stopping the medication suddenly.

However, if you do not take the medicine for as long as it is prescribed, your parasitic infection will not be cured. It is vital that you complete the ivermectin course prescribed for you.

Ivermectin and pregnancy

Not enough information is available regarding the effects of ivermectin during pregnancy.⁴

Even under strict medical supervision, ivermectin must only be used when absolutely necessary during pregnancy.

Please inform your doctor if you are pregnant or plan to become pregnant when taking this medication. Also, let them know if you become pregnant during your treatment with ivermectin. During pregnancy, ivermectin must only be used if the medicine’s benefits outweigh the risks.

Ivermectin and breastfeeding

Studies have shown that ivermectin passes into breast milk. Please tell your doctor if you are breastfeeding your baby, as ivermectin in breast milk might affect the infant.

Missed doses

If you have been prescribed a single-dose ivermectin tablet and you missed taking it, take it as soon as possible. If you are prescribed multiple doses and are closer to the time of the next dose, please skip the missed dose and take the next dose of ivermectin at the regular time.

Do not double the amount of medication you take to make up for a missed dose.

Drug interactions

Drug interactions can cause side effects and change how medications work. There is a risk of other drugs interacting with ivermectin. These include over-the-counter (OTC) drugs, prescription drugs, herbal remedies, and vitamins. Some products/drugs that may interact with ivermectin include the following:

Tell your doctor which medicines you are currently taking. You also need to inform them about any medication you stop or start taking during treatment with ivermectin.

Allergy information

Ivermectin rarely causes an allergic reaction. Notify your doctor about any symptoms of an allergic reaction, such as:

  • Rash

  • Itching or swelling of the tongue, throat, or face

  • Trouble breathing

  • Severe dizziness

This is not a complete list of allergic reactions. Please get in touch with your doctor immediately if you notice any others.

Ivermectin might contain ingredients or components you are allergic to, so let your doctor know about any known drug allergies. Your doctor must also be aware of a known allergy to this medication.

Drug approval history

Ivermectin was discovered in the late 1970s. It was initially introduced as a veterinary drug to prevent and treat multiple external and internal parasites in dogs, horses, and livestock.⁵

The brand of ivermectin, Stromectol, received approval in 1996.⁶

Today, the FDA has approved the drug as a treatment for intestinal strongyloidiasis, onchocerciasis, several other intestinal parasitic worm infections, rosacea, head lice, and some cases of scabies.

Tips and advice for taking ivermectin

Following these tips could help you take ivermectin safely and get the best results.

  • Ivermectin is a prescription drug. You must always take this medicine under medical supervision.

  • Do not take more or less ivermectin than your doctor prescribes for you.

  • Tell your doctor about any side effects or allergic reactions you experience while taking this drug.

  • Never swallow topical ivermectin preparations.

  • Never take veterinary ivermectin preparations.

  • Ivermectin is not approved for COVID-19 prevention or treatment and must not be used for this purpose.

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Here at HealthMatch, we’ve done our best to ensure that the information provided in this article is helpful, up to date, and, most importantly, accurate.

However, we can’t replace the one-to-one advice of a qualified medical practitioner or outline all of the possible risks associated with this particular drug and your circumstances.

It is therefore important for you to note that the information contained in this article does not constitute professional medical or healthcare advice, diagnosis or recommendation of treatment and is not intended to, nor should be used to, replace professional medical advice. This article may not always be up to date and is not exhaustive of all of the risks and considerations relevant to this particular drug. In no circumstances should this article be relied upon without independent consideration and confirmation by a qualified medical practitioner.

Your doctor will be able to explain all possible uses, dosages, precautions, interactions with other drugs, and other potential adverse effects, and you should always talk to them about any kind of medication you are taking, thinking about taking or wanting to stop taking.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.