Ivermectin

Key facts

• Ivermectin is an antiparasitic medicine, taken as tablets for certain worm infections or applied as a cream or lotion for skin conditions caused by mites.
• Oral doses for parasitic infections are usually taken on an empty stomach, sometimes as a single dose or a short course repeated after some weeks, depending on the parasite.
• Ivermectin is not an approved or proven treatment or prevention for COVID-19 or any other viral illness, and it is not a general travel medicine. Veterinary ivermectin, formulated for animals at very different strengths, has caused serious poisoning in people who took it for unapproved uses.
• Seek urgent care for confusion, difficulty walking, seizures, or a severe rash after taking it.

What ivermectin treats

Ivermectin treats specific parasitic infections, including strongyloidiasis (a roundworm infection), onchocerciasis (river blindness, caused by a parasitic worm spread by blackflies), and other worm infections where prescribed. Topical ivermectin treats scabies (a mite infestation causing intense itching), head lice, and the inflammatory lesions of rosacea. Each form and dose is matched to the specific parasite; it does not treat bacterial, fungal, or viral infections.

How ivermectin works

Ivermectin binds to channels in the nerve and muscle cells of susceptible parasites, keeping them open so the cells stay overactive; the parasite becomes paralysed and dies. Human nerve cells are largely protected from this effect because the drug does not readily cross into the human brain at normal doses.

Before you take it

• Tell your prescriber if you are pregnant, breastfeeding, or have liver disease.
• If you have lived in Central or West Africa and may have a heavy Loa loa worm infection, tell your prescriber before mass treatment for onchocerciasis; ivermectin has rarely caused severe, sometimes fatal, brain reactions in people with high Loa loa levels.
• Never take veterinary ivermectin products intended for animals; their strength and formulation are not safe for human use.
• Alcohol and other sedating substances can worsen dizziness during treatment.

Side effects

Common effects include mild nausea, dizziness, headache, and itching or rash, which can also reflect the body's reaction to dying parasites rather than the drug itself.

Stop and seek urgent medical care for any of these:

• Confusion, severe drowsiness, difficulty walking, or seizures.
• Sudden vision changes or eye pain.
• Swelling of the face, lips or throat, or a rash that spreads quickly.
• Persistent vomiting or diarrhoea with signs of dehydration.

Safety essentials

• Only take ivermectin for a confirmed or strongly suspected parasitic infection, prescribed and dosed for that specific condition; it has no proven role against viral illness, including COVID-19.
• Never substitute veterinary formulations for human ones. They are dosed for animal body weights and have caused overdose and hospitalisation in people who used them.
• If you have travelled from an area with Loa loa, mention it before treatment for onchocerciasis, since screening can prevent a rare but serious brain reaction.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.