Antiparasitic Drug Comparison Tool
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When doctors need to clear parasites, Ivermectin is the brand name Stromectol, a broad‑spectrum antiparasitic that’s been on the market since 1981. It’s used for everything from river blindness to strongyloidiasis, but many clinicians wonder if other drugs might fit better for specific infections, cost concerns, or patient tolerability. This guide lines up the most common alternatives, weighs their pros and cons, and gives you a practical decision‑tree you can use in the clinic or at home.
How Ivermectin Works and When It’s Preferred
Ivermectin binds to glutamate‑gated chloride channels in the nerve and muscle cells of invertebrates. The resulting hyperpolarisation paralyzes the parasite, ending the infection. Because human cells lack these channels, the drug enjoys a wide safety margin.
- Key indications: Onchocerciasis (river blindness), Lymphatic filariasis, Strongyloides stercoralis, Scabies, and certain ectoparasitic infections.
- Typical adult dose: 200 µg/kg orally, single dose for most indications; sometimes repeated after 2 weeks for strongyloidiasis.
- Regulatory status: Approved by the U.S. Food and Drug Administration for human use; also listed on the World Health Organization’s Essential Medicines List.
Top Alternative Antiparasitics
Below are the most frequently cited replacements for Ivermectin. Each has a distinct mechanism, spectrum, and safety profile.
Albendazole - a benzimidazole that interrupts microtubule formation in helminths. It’s the go‑to drug for neurocysticercosis and a broad range of soil‑transmitted helminths.
Mebendazole - another benzimidazole, often used for mild intestinal worm infections such as Ascaris, hookworm, and Trichuris.
Praziquantel - a cyclo‑tetra‑pyrrolidine that increases cell membrane permeability in trematodes and cestodes. It’s the drug of choice for schistosomiasis and tapeworm infections.
Diethylcarbamazine (DEC) - works by altering the surface structure of microfilariae, making them more susceptible to host immunity. Primarily prescribed for lymphatic filariasis in regions where Ivermectin resistance is reported.
Nitazoxanide - a nitrothiazolyl‑salicylamide with broad activity against protozoa and some helminths. Often chosen for cryptosporidiosis and Giardia infections.
The World Health Organization regularly updates the recommended drug for each parasitic disease based on efficacy, resistance patterns, and safety.
Side‑Effect Snapshot
- Ivermectin: mild nausea, dizziness, transient rash; rare neurotoxicity at high doses.
- Albendazole: hepatotoxicity (monitor LFTs), abdominal pain, alopecia (long‑term).
- Mebendazole: similar to albendazole but lower hepatotoxic risk; occasional rash.
- Praziquantel: short‑lasting headache, abdominal cramping, occasional urticaria.
- DEC: itching, fever, & occasionally severe allergic reactions in Loa loa‑co‑endemic areas.
- Nitazoxanide: metallic taste, mild GI upset, rare yellow‑eye discoloration.
Comparison Table
| Drug | Primary Indications | Typical Adult Dose | FDA Approval | Common Side Effects | Average Cost (US$) |
|---|---|---|---|---|---|
| Ivermectin | Onchocerciasis, Strongyloidiasis, Scabies | 200 µg/kg PO, single dose (repeat if needed) | Approved | Nausea, dizziness, rash | 3 - 6 per tablet |
| Albendazole | Neurocysticercosis, Toxocariasis | 400 mg PO BID for 3 days | Approved | Hepatotoxicity, abdominal pain | 4 - 8 per 400 mg tablet |
| Mebendazole | Ascaris, Hookworm, Trichuris | 100 mg PO BID for 3 days | Approved | Abdominal cramps, mild rash | 2 - 5 per 100 mg tablet |
| Praziquantel | Schistosomiasis, Tapeworms | 40 mg/kg PO single dose | Approved | Headache, abdominal cramping | 7 - 12 per 600 mg tablet |
| Diethylcarbamazine | Lymphatic filariasis (W. bancrofti) | 6 mg/kg PO daily for 12 days | Approved in limited regions | Itching, fever, possible severe allergy | 5 - 9 per 50 mg tablet |
| Nitazoxanide | Giardia, Cryptosporidium | 500 mg PO BID for 3 days | Approved | Metallic taste, mild GI upset | 10 - 15 per 500 mg tablet |
Choosing the Right Drug: Decision‑Tree Guide
- Identify the parasite.
- If it’s a filarial worm (Onchocerca, Strongyloides) → Ivermectin is first‑line.
- If it’s a tapeworm or fluke → Praziquantel is the clear winner.
- If dealing with neurocysticercosis or soil‑transmitted helminths → Albendazole or Mebendazole.
- If the infection is protozoan (Giardia, Cryptosporidium) → Nitazoxanide.
- Check patient-specific factors.
- Pregnancy: Albendazole is contraindicated; Ivermectin is category C, Praziquantel preferred.
- Liver disease: Prefer Mebendazole (lower hepatotoxicity) over Albendazole.
- Known drug‑resistance zones: Consider DEC for filariasis where Ivermectin resistance is emerging.
- Consider cost and accessibility.
- In low‑resource settings, generic Ivermectin often costs the least per dose.
- Praziquantel can be expensive in high‑income markets but is subsidized in many endemic regions.
Following this flow helps avoid trial‑and‑error prescribing and reduces the risk of adverse events.
Safety Tips & Monitoring
- Always verify dosage based on weight; overdosing Ivermectin above 2 mg/kg can cause neurotoxicity.
- For Albendazole and Mebendazole, order baseline liver function tests and repeat after a week of therapy.
- Praziquantel may trigger severe reactions in patients with heavy schistosome burdens - consider pre‑treatment steroids.
- DEC should be avoided in patients with high Loa loa microfilaremia (<30,000 mf/mL) due to risk of encephalopathy.
Bottom Line
If you’re dealing with common helminths and need a single‑dose, well‑tolerated option, Ivermectin remains the most practical choice. For central nervous system involvement, tapeworms, or resistant filarial strains, switch to albendazole, praziquantel, or DEC as the situation dictates. Always match the drug to the parasite, weigh patient health factors, and keep an eye on cost.
Can I use Ivermectin for COVID‑19?
No. Major health agencies, including the FDA and WHO, have repeatedly stated that Ivermectin has no proven benefit for COVID‑19 and may cause harm when taken at unapproved doses.
Is Ivermectin safe for children?
It is approved for children weighing at least 15 kg for certain indications. Below that weight, safety data are limited, so doctors usually choose albendazole or mebendazole.
What’s the difference between Ivermectin and Albendazole?
Ivermectin targets chloride channels in parasites, giving rapid paralysis, while albendazole disrupts microtubule formation, which is slower but effective against tissue‑invading worms like cysticercus.
How long does a single dose of Ivermectin stay in the body?
The plasma half‑life is about 18 hours, but metabolites can be detected for up to 5 days. Most therapeutic effect happens within 24 hours.
When should I consider Diethylcarbamazine instead of Ivermectin?
If you’re treating lymphatic filariasis in an area where Ivermectin resistance has been documented, DEC is the recommended alternative, provided the patient has no Loa loa infection.
Kevin Sheehan 19.10.2025
When we talk about antiparasitic stewardship, we’re really navigating a philosophical landscape of risk versus benefit.
Every drug choice reflects a set of values about patient safety, public health, and economic reality.
Ivermectin, with its decades‑long safety record, often becomes the default not because it’s superior for every parasite but because clinicians gravitate toward the familiar.
Yet familiarity can breed complacency, and the alternatives you listed each carve out niche advantages that deserve serious consideration.
Albendazole’s hepatotoxic potential forces us to monitor liver enzymes, which in low‑resource settings can be a prohibitive barrier.
Mebendazole, while gentler on the liver, suffers from variable bioavailability that can blunt its efficacy against heavy burdens.
Praziquantel’s rapid trematode kill is a boon, but its price tag and occasional severe reactions remind us that cost and safety are inseparable.
DEC’s niche use in filariasis‑resistant zones illustrates how resistance shapes drug policy, underscoring the need for surveillance.
Nitazoxanide’s broad protozoal spectrum makes it a versatile tool, yet its metallic taste can affect adherence.
The decision‑tree you propose is useful, but it must be coupled with local resistance patterns and patient comorbidities.
Pregnancy, for instance, shifts the balance dramatically: albendazole is contraindicated, pushing clinicians toward praziquantel or carefully weighted ivermectin use.
Liver disease similarly nudges us toward mebendazole, despite its lower efficacy for certain helminths.
Moreover, the ethical dimension of affordable access cannot be ignored; generic ivermectin often remains the cheapest option, influencing public‑health programs.
In high‑income markets, the higher costs of praziquantel or nitazoxanide may be justified by superior outcomes, but equity demands we consider subsidization.
Ultimately, the art of prescribing antiparasitics lies in synthesizing mechanistic knowledge, epidemiologic data, and the lived realities of patients.
Only by maintaining a critical, open‑minded stance can we avoid the trap of defaulting to one drug without merit.