Ivermectin for Humans: FDA-Approved Uses, Strengths, Dosage and How to Get a Prescription
- Dr. Kimryn Rathmell
- 3 days ago
- 8 min read
Updated: 2 days ago
Ivermectin is one of the most important antiparasitic medicines ever developed. Since its discovery in the 1970s and introduction into human medicine in the 1980s, ivermectin has been administered more than two billion times worldwide — primarily in mass drug administration campaigns that dramatically reduced the burden of onchocerciasis (river blindness) and lymphatic filariasis in Africa and Latin America. In 2015, its co-discoverers William Campbell and Satoshi Omura were jointly awarded the Nobel Prize in Physiology or Medicine for their work on ivermectin.
In the United States in 2026, ivermectin for human use is an FDA-approved prescription medication available in tablet form, with a well-established safety record for its approved indications spanning more than three decades of clinical use. This guide focuses on what ivermectin is actually approved to treat in humans, how the dosage is calculated, the different tablet strengths available, what the correct prescription pathway looks like, and the important distinctions between human-grade and animal formulations.
The FDA provides official information on ivermectin and its approved human uses at: https://www.fda.gov/consumers/consumer-updates/ivermectin-and-covid-19
What is Ivermectin? — The Mechanism
Ivermectin is a semisynthetic macrocyclic lactone derived from the bacterium Streptomyces avermitilis. It works as an antiparasitic agent by binding selectively and with high affinity to glutamate-gated chloride ion channels found in invertebrate nerve and muscle cells. This binding causes an increase in cell membrane permeability to chloride ions, resulting in hyperpolarisation of the nerve or muscle cell — effectively paralysing and killing the parasite.
Critically, the glutamate-gated chloride channels targeted by ivermectin do not exist in mammals — which is why ivermectin has an excellent safety profile in humans when used at approved doses. The blood-brain barrier in healthy adults also prevents ivermectin from accessing the central nervous system in significant quantities.
This selective toxicity — lethal to a wide spectrum of parasites, very well tolerated by humans — is what makes ivermectin such a clinically valuable medicine.
FDA-Approved Uses of Ivermectin for Humans
As of 2026, oral ivermectin tablets are FDA-approved for two specific indications in humans:
1. Intestinal Strongyloidiasis (caused by Strongyloides stercoralis):
Strongyloidiasis is infection with the intestinal roundworm Strongyloides stercoralis — a parasitic nematode capable of unique autoinfection, meaning it can multiply within the human host indefinitely without external re-exposure. This makes it one of the few parasitic infections capable of persisting for decades after the initial exposure. It is particularly dangerous in immunocompromised individuals (those on corticosteroids, transplant recipients, HIV-positive patients) — in whom it can cause hyperinfection syndrome, a life-threatening dissemination throughout the body.
Ivermectin is the treatment of choice for strongyloidiasis. A single oral dose of 200 mcg/kg achieves cure rates of 64–100% in clinical studies. It significantly outperforms the older treatment (thiabendazole) in both efficacy and tolerability. Follow-up stool examinations are performed to confirm eradication.
2. Onchocerciasis (River Blindness, caused by Onchocerca volvulus):
Onchocerciasis is caused by the filarial nematode Onchocerca volvulus, transmitted by the bite of blackflies (Simulium species) that breed near fast-flowing rivers — giving rise to the common name "river blindness." It causes severe skin disease and progressive visual impairment leading to blindness from the body's inflammatory response to dying microfilariae in the eye.
Ivermectin kills the microfilariae (larval stages) of Onchocerca volvulus, reducing the burden that drives eye and skin disease. Crucially, it does not kill adult Onchocerca worms — therefore repeated treatment at 6–12 month intervals is required. It is used both for individual patients and in mass drug administration campaigns.
In the United States, onchocerciasis is rare and seen primarily in immigrants or travellers from endemic areas (sub-Saharan Africa, parts of Latin America and Yemen).
Important note: Ivermectin is NOT approved by the FDA for the treatment or prevention of COVID-19. Clinical trials have not demonstrated efficacy for this purpose.
Ivermectin Tablet Strengths Available
Human ivermectin is available in tablet form in several strengths. The appropriate strength for a given patient is determined by body weight — since dosing is calculated per kilogram:
Strength | Standard Dose Use | Notes |
3 mg tablet | Original FDA-approved Stromectol strength; multiple tablets taken together per weight-based dosing chart | Most widely available generic strength in USA |
6 mg tablet | Allows fewer tablets for most adults; convenient for weight-based dosing | Available at TheMedicineKart: Ivermectin 6mg |
12 mg tablet | Higher-strength tablet; reduces pill burden further for weight-based dosing | Available at TheMedicineKart: Ivermectin 12mg |
15 mg tablet | Used in some weight-based protocols particularly for larger adults | Available at TheMedicineKart: Ivermectin 15mg |
20 mg tablet | Higher-dose formulation for larger body weight patients | Available at TheMedicineKart: Ivermectin 20mg |
Weight-Based Dosage Guidelines
Ivermectin dosing in humans is calculated based on body weight in kilograms, following the FDA-approved Stromectol prescribing information:
For Strongyloidiasis:
Single oral dose of approximately 200 mcg (0.2 mg) per kg of body weight, taken on an empty stomach with water.
For Onchocerciasis:
Single oral dose of approximately 150 mcg (0.15 mg) per kg of body weight, taken on an empty stomach with water. Retreatment at 6–12 month intervals until the at-risk period has passed.
Body Weight | Strongyloidiasis Dose (200 mcg/kg) | Onchocerciasis Dose (150 mcg/kg) |
15–24 kg | 3 mg (1 x 3mg tablet) | 3 mg |
25–35 kg | 6 mg (2 x 3mg OR 1 x 6mg) | 4.5 mg |
36–50 kg | 9 mg (3 x 3mg) | 6 mg (1 x 6mg) |
51–65 kg | 12 mg (4 x 3mg OR 1 x 12mg) | 9 mg |
66–79 kg | 15 mg (5 x 3mg OR 1 x 15mg) | 12 mg (1 x 12mg) |
80 kg and above | 200 mcg/kg calculated — prescriber to determine | 150 mcg/kg calculated |
Always take ivermectin on an empty stomach (at least 1 hour before or 2 hours after food) with a full glass of water. Food — particularly fatty food — significantly increases ivermectin absorption and may raise blood levels to potentially adverse concentrations.
The MedlinePlus Drug Information page provides comprehensive patient-level information on ivermectin including dosage, storage, and safety at: https://medlineplus.gov/druginfo/meds/a607069.html
Human Ivermectin vs Animal Ivermectin — A Critical Distinction
One of the most important safety messages about ivermectin is the absolute distinction between human-approved formulations and veterinary products:
Human ivermectin (Stromectol and generics):
Precisely dose-calibrated tablets for human body weights
Formulated and tested for human pharmacokinetics and safety
Manufactured under human pharmaceutical GMP standards
Available in 3mg, 6mg, 12mg, 15mg, and 20mg tablet strengths
Requires a valid prescription from a licensed US healthcare provider
Animal ivermectin:
Formulated for the physiology and body mass of horses, cattle, sheep, and other animals — body weights of hundreds of kilograms
Concentrations designed for animals are vastly different from human doses
May contain excipients (inactive ingredients) unsafe for human consumption
Not subject to human pharmaceutical manufacturing standards
Taking animal ivermectin as a human is dangerous and potentially fatal
The FDA has received multiple reports of patients requiring hospitalisation after taking veterinary ivermectin intended for animals. Never use animal formulations. The dramatic difference in concentration and formulation makes safe human dosing from animal products impossible without pharmacological expertise.
Off-Label Use of Ivermectin for Scabies
While the two FDA-approved indications are strongyloidiasis and onchocerciasis, oral ivermectin is also widely used off-label in the USA for scabies — infestation with the mite Sarcoptes scabiei — particularly in cases of:
Crusted (Norwegian) scabies — a severe, highly contagious form in immunocompromised patients where topical treatments alone are insufficient
Treatment failures with topical permethrin
Large institutional outbreaks where treating all individuals with topical therapy is logistically challenging
Patients unable to apply topical treatments effectively
The typical off-label oral ivermectin dose for scabies is 200 mcg/kg as a single dose, repeated after 7–14 days. This off-label use is supported by multiple clinical studies and is referenced in CDC and WHO scabies treatment guidelines.
Off-label prescribing is entirely legal in the United States — physicians may prescribe any approved medication for an unapproved indication when they judge it medically appropriate for an individual patient.
How to Get a Prescription for Ivermectin in 2026
Ivermectin tablets for human use require a valid prescription from a licensed US healthcare provider. The prescription pathway:
In-person consultation:
Primary care physician, infectious disease specialist, travel medicine clinic, or dermatologist
A clinical evaluation establishing the indication (confirmed or suspected parasitic infection, returning traveller from endemic area, scabies diagnosis, etc.)
Prescription written and filled at a licensed US pharmacy
Telehealth consultation (2026):
In 2026, telehealth has significantly expanded access to specialist consultations for parasitic conditions. Licensed telehealth providers can evaluate symptoms, review travel history, and issue a valid prescription when clinically appropriate. This is a legal and legitimate pathway for patients in rural areas or those without easy access to infectious disease specialists.
State-level OTC access (limited):
As of early 2026, a small number of states — including Texas, Tennessee, Arkansas, and Idaho — have enacted laws permitting licensed pharmacists to dispense ivermectin without a physician prescription under specific pharmacist consultation protocols. This applies only in those states and only through licensed pharmacies operating under the applicable state law.
What to look for in a pharmacy:
When filling a prescription for ivermectin — whether in-person or through a mail-order pharmacy — verify:
The pharmacy is licensed in your state
It is accredited by VIPPS (Verified Internet Pharmacy Practice Sites) if ordering online — the NABP (National Association of Boards of Pharmacy) VIPPS programme is the gold standard for online pharmacy verification in the USA
A valid prescription is always required (except in the few states with OTC access laws)
The product is labelled for human use — not animal or veterinary formulations
For our complete guide on treating Onchocerciasis (River Blindness) with ivermectin: [Onchocerciasis (River Blindness): Ivermectin Treatment Guide]
For our complete overview of all ivermectin-treated parasitic conditions including strongyloidiasis: [Ivermectin: Complete Guide to Uses, Dosage and Safety]
For our guide to Mebendazole — a complementary antiparasitic medicine used alongside ivermectin for some helminth infections: [Mebendazole: Uses, Dosage and Complete Guide]
The official FDA prescribing information (Stromectol label) including complete dosage tables is available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2007/050742s019s021lbl.pdf
Frequently Asked Questions
1. What conditions is ivermectin FDA-approved to treat in humans?
As of 2026, oral ivermectin tablets are FDA-approved for two conditions: intestinal strongyloidiasis caused by the nematode Strongyloides stercoralis, and onchocerciasis (river blindness) caused by Onchocerca volvulus. Topical ivermectin formulations are separately approved for head lice (ivermectin lotion 0.5% — Sklice, available OTC) and rosacea (ivermectin cream 1% — Soolantra, prescription). Physicians may also prescribe oral ivermectin off-label for other parasitic conditions including scabies when medically appropriate.
2. How is the correct dose of ivermectin for humans calculated?
Human ivermectin dosing is weight-based — calculated per kilogram of body weight. For strongyloidiasis, the standard dose is 200 micrograms per kilogram as a single oral dose. For onchocerciasis, the standard dose is 150 micrograms per kilogram as a single oral dose, repeated at 6 to 12 month intervals. Your prescribing healthcare provider will calculate the appropriate dose and the corresponding number and strength of tablets based on your weight.
3. Why should ivermectin always be taken on an empty stomach?
Taking ivermectin with food — particularly high-fat food — significantly increases its absorption and can raise blood levels considerably above the intended therapeutic range. The FDA-approved dosing is calibrated for fasting administration. Taking ivermectin with a fatty meal can increase blood levels by up to two to three times compared to fasting, potentially increasing adverse effects. Always take ivermectin with a full glass of water at least one hour before eating.
4. Is ivermectin safe? What are the side effects?
Ivermectin has an excellent safety profile when used at approved doses for approved indications — supported by more than three decades of clinical use and over two billion doses administered worldwide. Common mild side effects include dizziness, nausea, diarrhoea, itching, and skin rash. In patients being treated for onchocerciasis, a Mazzotti reaction may occur — fever, itching, rash, and joint pain caused by the inflammatory response to dying microfilariae — not by drug toxicity. Serious adverse effects at standard doses are very rare. Ivermectin must not be used in pregnancy (teratogenic in animal studies) and should be used with caution in patients with liver disease.
5. What is the difference between ivermectin for humans and ivermectin for animals?
Human ivermectin is manufactured to pharmaceutical grade standards in precisely calibrated tablet doses (3mg, 6mg, 12mg, 15mg, 20mg) appropriate for human body weights. Animal ivermectin is formulated at concentrations designed for the physiology and body mass of large animals — horses, cattle, sheep — which weigh hundreds of kilograms. The concentrations, excipients, and formulations are entirely different and not appropriate for human use. Taking animal ivermectin is dangerous and has resulted in hospitalisations. Only use human-grade ivermectin tablets dispensed from a licensed pharmacy on the basis of a valid prescription.
Comments