Ivermectin – Comprehensive Patient Guide for Australia
Basic Product Information
| International Nonproprietary Name (INN) | Ivermectin |
|---|---|
| Australia Brand Names | Stromectol®, Ivomec® (veterinary use; human use under authority only) |
| Anatomical Therapeutic Chemical (ATC) Code | P02CF01 |
| Available Forms & Strengths | Tablets: 3 mg, 6 mg, 12 mg (human use by authority); Cream: 1% (for skin conditions) |
| Main Manufacturers | MSD (Merck Sharp & Dohme), generic manufacturers |
| Prescription Status | Prescription Only Medicine (S4) |
Mechanism of Action
For Patients: Ivermectin is a medicine that treats certain infections caused by parasites (such as worms, lice, or mites). It works by killing the parasites or stopping their ability to grow and multiply in your body.
For Specialists: Ivermectin binds selectively and with high affinity to glutamate-gated chloride channels, which are found in the nerve and muscle cells of invertebrates. This leads to increased permeability of the cell membrane to chloride ions, causing hyperpolarisation, paralysis, and death of the parasite. Its mammalian safety is attributed to the absence of these channels in humans and limited penetration of ivermectin into the CNS due to the blood-brain barrier.
Pharmacokinetics
- Absorption: Rapidly absorbed after oral administration; peak plasma concentrations typically reached in 3–5 hours.
- Bioavailability: Increases with fatty meals (up to 2.5 times higher).
- Metabolism: Metabolised in the liver, primarily by CYP3A4 isoform.
- Elimination: Excreted mainly in the faeces (~90%); less than 2% excreted in urine.
- Half-life: Approximately 18 hours (range 12–36 hours).
Use in Everyday Life and Best Practices
In Australia, ivermectin is used under medical supervision to treat specific conditions such as scabies, head lice, and some tropical worm infections (e.g., strongyloidiasis). It is usually taken as a single dose or as a short course, depending on the condition. Usage outside of these indications is not recommended and may be illegal.
- Take the medicine as prescribed by your healthcare provider. Do not self-medicate or use animal formulations.
- For oral tablets: swallow with a full glass of water; do not chew or crush unless instructed.
- For scabies and lice: clothing, bed linen, and towels should be washed on the day of treatment to avoid reinfection.
- Please consult your doctor or pharmacist for advice on when to repeat doses or what else may be needed for complete treatment.
Dosing in the Morning vs Evening
- Morning: Some patients may prefer taking ivermectin in the morning for convenience and better compliance with fasting states (required for optimal absorption).
- Evening: No significant difference in clinical efficacy, but avoid if heavy meals are planned soon afterwards.
- Tip: Regularity is important—take the dose at the same time each day if a course is prescribed (rather than a single dose).
- Set reminders to help maintain consistent dosing, especially for multi-day regimens.
Taking with Food or on an Empty Stomach
- Ivermectin is best absorbed on an empty stomach—at least one hour before or two hours after eating.
- Fatty meals increase absorption and may raise the risk of side effects.
- In Australia, a typical diet may include fats at breakfast and dinner; plan dosing to avoid major meals.
- Small sips of water are allowed, but avoid milk or juices around the time of consumption.
Interaction Warnings
| Interaction Type | Substance | Recommendation |
|---|---|---|
| Medications | Warfarin, cyclosporine, other CYP3A4 inhibitors/inducers | Monitor for bleeding, toxicity. Inform your doctor about all medications. |
| Food | High-fat meals | May increase absorption; stick to fasting recommendations unless directed. |
| Alcohol | Alcoholic beverages | Avoid during treatment; may worsen side effects (dizziness, drowsiness). |
| Other | Other antiparasitic drugs | May require dose adjustments if combined. |
Indications (TGA-Approved and Supported Off-label Uses)
| Condition | Use Status | Notes |
|---|---|---|
| Strongyloidiasis (intestinal threadworm) | Official, TGA Approved | Preferred agent in Australia |
| Scabies (including crusted scabies) | Official, TGA Approved (oral form) | For patients where topical treatment has failed or is not practical |
| Head lice | Off-label | Used where other treatments are ineffective |
| Onchocerciasis | Not prevalent in Australia | Travel medicine setting only |
| Other parasitic worm infections | Occasionally, off-label | Specialist advice |
Dosing According to Clinical Indications
| Indication | Adults | Children* | Elderly |
|---|---|---|---|
| Strongyloidiasis | 200 µg/kg as a single dose | 200 µg/kg single dose (if ≥15 kg) | Same as adult; monitor comorbidities |
| Scabies (classic) | 200 µg/kg, repeat after 7–14 days as needed | Same as adult | Same as adult |
| Scabies (crusted) | 200 µg/kg on days 1, 2, 8, 9, and 15 | Same as adult | Same as adult |
| Head lice (off-label) | 200 µg/kg, may repeat after 7 days | Same as adult | Same as adult |
*Safety not established for children under 15 kg or under 5 years old.
Safety Profile & Side Effects
| Frequency | Side Effects |
|---|---|
| Common (>1%) | Nausea, diarrhoea, abdominal pain, dizziness, drowsiness, rash, itching |
| Occasional | Headache, fever, muscle aches, mild swelling of the face/limbs |
| Rare (<0.1%) | Blurred vision, severe skin reaction, confusion, allergic reactions (anaphylaxis) |
| Warnings | Use with caution in severe liver impairment; not recommended in pregnancy or breastfeeding without specialist advice |
Guidelines for Proper Use
- Always take ivermectin as prescribed by your Australian doctor or pharmacist.
- Adhere to fasting guidelines unless otherwise advised.
- Wash clothes and bedding on treatment day to prevent re-infestation.
- Complete the full course, even if symptoms improve before finishing.
- Never share your medication with others; this is illegal and unsafe.
- Report any unusual side effects or allergic reactions immediately.
- If you miss a dose, take it as soon as you remember. If it is almost time for the next dose, skip the missed dose—do not double up.
Alternative Treatment Options
- Permethrin cream (topical) – First-line for scabies and lice; available OTC in Australia. Generally well tolerated, but less effective in crusted (severe) scabies or if topical use isn’t possible.
- Benzyl benzoate lotion – Alternative for scabies, but may irritate skin, especially in children.
- Malathion lotion – For head lice; a choice if others fail. Flammable and pungent odour.
- Albendazole/mebendazole – Used for some intestinal worms; not effective for scabies or lice.
- All drugs reimbursed only under special access schemes or with certain conditions met under Medicare and the Pharmaceutical Benefits Scheme (PBS).
Legal, Registration and Reimbursement Status in Australia
- Ivermectin is listed as an S4 (Prescription Only) medicine under the Therapeutic Goods Administration (TGA).
- Human-grade ivermectin is registered for use in specific conditions (e.g., scabies, strongyloidiasis); veterinary use for animals only.
- Not available over-the-counter or for non-approved indications (e.g., COVID-19) in community pharmacies.
- May be supported by the PBS for specific conditions; consult your prescriber for eligibility.
- Importation without a prescription is illegal and poses health risks.
Latest Research and Clinical Guidance (2022–2025)
- Scabies: Early oral ivermectin, alongside topical agents, is now recommended in institutional outbreaks and for crusted scabies (Therapeutic Guidelines: Dermatology, 2024).
- COVID-19: Large-scale studies show no benefit of ivermectin for prevention or treatment (see: ANZICS Infectious Diseases Guidelines, 2024). Off-label use for viral conditions is not recommended.
- Children: Ongoing safety studies endorse use in children 15 kg or more (Australian Paediatric Infectious Diseases guidance, 2025).
- Aboriginal and Torres Strait Islander Health: Mass drug administration programs in remote communities show significant reduction in scabies prevalence (The Lancet Regional Health—Western Pacific, 2023).
Availability and Delivery
| Popular Pack Size | Indicative Retail Price (AUD) | Estimated Pharmacy Delivery* (Business days) |
|---|---|---|
| 4 x 3 mg tablets | $27–$40 | Sydney: 1–2; Melbourne: 1–2; Brisbane: 1–3; Perth: 2–4; Adelaide: 1–2 |
| 8 x 3 mg tablets | $52–$80 | Same as above |
| Cream 30 g (1%) | $18–$30 | Same as above |
*Varies by supplier, city, and public holidays. Prescription required.
FAQ – Common Patient Questions
- Q: Can I take ivermectin if I am pregnant or breastfeeding?
A: Ivermectin is generally not recommended during pregnancy or breastfeeding unless advised by a specialist, due to limited safety data. - Q: Should I stop my other medications when taking ivermectin?
A: No, but always inform your doctor and pharmacist about all medicines you use. Some medicines may interact, and your prescriber may need to adjust dosing or monitoring. - Q: How long before I start to feel better with ivermectin?
A: Symptoms such as itching or visible parasites usually begin to improve within a few days, but completing the full prescribed course is important to eradicate the infection. - Q: Can I buy ivermectin from an online pharmacy or overseas?
A: No. In Australia, it is illegal to obtain ivermectin without a valid prescription. Unregulated products can be dangerous or counterfeit. - Q: What should I do if I experience side effects?
A: Mild effects are common and usually temporary. For severe or concerning symptoms (such as swelling, trouble breathing, severe rash), seek immediate medical attention.
For More Information: Please consult your GP, pharmacist, or the official Therapeutic Goods Administration (TGA) site for up-to-date medicine safety alerts and consumer medicine information (CMI).
