The correct ivermectin dosage for humans is calculated by body weight, not a flat number. For strongyloidiasis, the standard dose is approximately 200 mcg per kg of body weight, taken as a single oral dose. For onchocerciasis (river blindness), the dose drops slightly to 150 mcg per kg, also as a single dose. Getting this right matters, so use the weight-based tables below rather than guessing.

How Ivermectin Works in the Body

Ivermectin is a member of the avermectin class of antiparasitic agents. According to DailyMed, it works by binding selectively and with high affinity to glutamate-gated chloride ion channels found in invertebrate nerve and muscle cells. This binding increases the permeability of the cell membrane to chloride ions, causing hyperpolarization of the parasite's nerve or muscle cells, leading to paralysis and death of the parasite.

Crucially, these glutamate-gated chloride channels either don't exist in mammals or exist at concentrations too low for ivermectin to affect at therapeutic doses. Ivermectin also does not readily cross the blood-brain barrier in humans. This is why the drug is highly effective against parasites while remaining well tolerated by patients at correct doses.

After you swallow a tablet, peak plasma concentrations occur at roughly 4 hours. The plasma half-life is approximately 18 hours, and the drug and its metabolites are cleared almost exclusively through the feces over an estimated 12 days. Less than 1% of the administered dose appears in urine. Ivermectin is primarily metabolized by the CYP3A4 liver enzyme, which is worth knowing if you take other medications that interact with that pathway.

Want a broader overview before reading the dosage specifics? Our article What is Ivermectin? Complete Guide to Uses, Benefits and Safety covers the full clinical picture.

Ivermectin Dosage for Strongyloidiasis

Strongyloidiasis is a roundworm infection caused by Strongyloides stercoralis, a parasite that can persist in the gut for decades if untreated. It's more common in tropical and subtropical regions, including northern Australia, and in people who have lived or travelled in those areas.

According to DailyMed, the recommended dose for strongyloidiasis is a single oral dose providing approximately 200 mcg of ivermectin per kg of body weight. Tablets are typically supplied in 3 mg strength, so the number you take depends on your weight.

In most cases, a single dose is all you need. However, follow-up stool examinations are important. At least three stool tests should be done over the three months following treatment to confirm the infection has cleared. If larvae reappear in stool, retreatment with ivermectin is indicated.

Clinical data supports this approach strongly. In controlled trials comparing ivermectin to albendazole, ivermectin at 170 to 200 mcg/kg achieved cure rates of 83 to 92%, compared to 45 to 55% for albendazole. Against thiabendazole, ivermectin performed comparably, with some studies showing 100% cure rates at the 200 mcg/kg dose.

For patients looking at combination antiparasitic options, Bandy-Plus Tablet (ivermectin 6 mg + albendazole 400 mg) is worth discussing with your doctor if you have a mixed or complex parasitic infection.

Ivermectin Dosage for Onchocerciasis (River Blindness)

Onchocerciasis is caused by the filarial worm Onchocerca volvulus, transmitted through blackfly bites. While not endemic to Australia, it affects travellers returning from sub-Saharan Africa and parts of Latin America.

The recommended dose for onchocerciasis is slightly lower than for strongyloidiasis: approximately 150 mcg per kg of body weight, as a single oral dose. Here's the weight-based table:

Retreatment for onchocerciasis can be considered at intervals as short as 3 months for individual patients, though mass treatment campaigns typically use 12-month intervals. Ivermectin is active against the tissue microfilariae of Onchocerca volvulus, but not against the adult worm form. This is why repeat dosing may be necessary over time.

In a double-blind, placebo-controlled clinical trial, a single 150 mcg/kg dose reduced skin microfilariae counts by 83.2% at day 3 and 99.5% at 3 months post-dose. That reduction of more than 90% was maintained for up to 12 months after the single dose.

If you want to compare how ivermectin stacks up against other antiparasitic treatments, read our detailed breakdown in Ivermectin vs Mebendazole: Complete Comparison Guide.

How to Take Ivermectin: Timing and Food Rules

Take ivermectin on an empty stomach, with a full glass of water. This is the standard clinical recommendation per DailyMed, and the reasoning matters.

When ivermectin is taken after a high-fat meal, bioavailability increases approximately 2.5-fold compared to fasting. While this sounds like more drug absorption would be better, it also means unpredictable plasma concentrations. The dose calculations above are calibrated for fasting administration. If you eat a fatty meal beforehand and absorb 2.5 times more drug than expected, you're outside the studied safety margin.

Practical tips for taking ivermectin correctly:

• Take the tablets first thing in the morning, before breakfast
• Wait at least 2 hours before eating
• Use plain water, not juice or milk
• Don't split tablets unless your doctor specifically instructs you to
• If you vomit within 30 minutes of taking the dose, contact your pharmacist about whether you need to redose

For most conditions, a single dose is sufficient. You don't need to repeat the dose unless follow-up testing shows persistent infection or your doctor advises retreatment.

Side Effects You Should Know About

Ivermectin is generally well tolerated at therapeutic doses. In four clinical studies involving 109 patients treated for strongyloidiasis at 170 to 200 mcg/kg, the most commonly reported adverse effects were dizziness (2.8%) and pruritus (2.8%). Nausea and diarrhea each occurred in 1.8% of patients. Other effects including fatigue, abdominal pain, vomiting, and rash were reported in under 1% of patients.

For patients treated for onchocerciasis, the side effect profile is different and partly driven by the immune response to dying parasites rather than the drug itself. This is called the Mazzotti reaction. It can include fever (22.6%), skin rash or edema (22.7%), itching (27.5%), and lymph node enlargement and tenderness. These reactions typically occur in the first 4 days after treatment and resolve without specific intervention in most cases.

More serious but rare adverse effects reported post-marketing include:

• Severe neurological effects: altered consciousness, confusion, somnolence, stupor, and in rare cases coma
• Stevens-Johnson syndrome and toxic epidermal necrolysis (very rare)
• Seizures
• Hepatitis and elevated liver enzymes
• Worsening of bronchial asthma

If you experience confusion, difficulty staying awake, or any neurological symptoms after taking ivermectin, seek medical attention immediately.

Patients on warfarin should be aware that post-marketing reports have documented increased INR when ivermectin was co-administered with warfarin. Monitor your INR closely if you're on anticoagulants and need to take ivermectin.

Who Should Avoid Ivermectin

Ivermectin tablets are contraindicated in anyone with a known hypersensitivity to any component of the formulation. If you've had an allergic reaction to ivermectin or any ingredient in the tablet previously, don't take it again without medical clearance.

Several groups need extra caution:

• People with Loa loa infection: Ivermectin can cause serious neurological events in patients with loiasis (African eye worm). If you've spent extended time in central or west Africa, discuss this risk with your doctor before taking ivermectin.
• Pregnant women: Ivermectin is not recommended during pregnancy. Discuss alternatives with your doctor.
• Children under 15 kg: Safety and dosing below this weight threshold haven't been established for standard tablet formulations.
• People on warfarin: As noted above, INR can increase. Monitor carefully and inform your prescriber.
• People on CYP3A4 inhibitors: Drugs that inhibit this liver enzyme can increase ivermectin concentrations. Examples include some antifungals, certain HIV medications, and some antibiotics. Check with your pharmacist.

Buying Ivermectin in Australia

In Australia, ivermectin is a Schedule 4 prescription-only medicine. This means you need a valid prescription from a registered Australian doctor to legally obtain it. The Therapeutic Goods Administration (TGA) has approved ivermectin for human use in specific parasitic infections, including strongyloidiasis and onchocerciasis.

Getting a prescription is straightforward if you have a confirmed or suspected parasitic infection. Australian GPs, infectious disease specialists, and travel medicine clinics can prescribe ivermectin. Telehealth services have also made it easier to consult a doctor from home, particularly relevant for Australians in rural or remote areas where parasitic infections may be more common.

Once you have a prescription, SafeRxPills offers a convenient option for Australians who prefer to order online. We stock Ivermaxx 80 mg, a high-strength ivermectin product, dispatched with standard shipping to Australian addresses. Delivery typically takes 7 to 14 business days depending on your location.

Pricing through SafeRxPills is significantly lower than what you'd pay at many retail pharmacies, particularly for patients who require ongoing or repeat treatment. All orders are dispatched discreetly, and our team is available to answer dosing or product questions before you order.

For full details on sourcing ivermectin locally as an Australian patient, see our dedicated page on buying ivermectin in Australia.

One practical note for Australian patients: if you're being treated for strongyloidiasis acquired in tropical northern Australia or after travel to a high-prevalence region, your treating doctor may recommend follow-up stool testing at 4 to 8 weeks post-treatment. Don't skip this step. Reinfection and treatment failure are both possible, and early detection means retreatment before the infection re-establishes.

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