Fenbendazole Dosage Calculator: Doses by Weight and Protocols

Important: Fenbendazole is a veterinary deworming medicine. It is not approved for human use by the FDA, EMA, MHRA, TGA or Health Canada, and its safety and dosing in people have not been established (Nguyen et al., 2024). SafeRxPills sells it for veterinary use only. The figures on this page describe what people following online protocols report taking; they are not a dosing recommendation.

A fenbendazole dosage calculator turns body weight into a daily figure using the rule most often quoted in online protocols: 1 mg per pound of body weight per day, about 2.2 mg per kilogram. For a 150-pound person that works out to 150 mg a day, and the protocols shared online range from roughly 150 to 300 mg a day.

The calculation itself is straightforward, but choosing the right protocol and understanding how to time your doses requires more nuance. Unlike traditional antiparasitic dosing where you treat an active infection and stop, many people use fenbendazole on extended schedules that involve cycling patterns.

How to Calculate Your Fenbendazole Dose

Start with your body weight in pounds. The rule quoted in most online protocols is 1 mg of fenbendazole per pound of body weight. By that rule, someone weighing 180 pounds arrives at 180 mg a day.

If you prefer metric, convert your weight to kilograms (divide pounds by 2.2) and multiply by 2.2 mg per kilogram. By this method a 70 kg person arrives at about 154 mg a day.

Most people round to the nearest available capsule strength. Fenbendazole 444mg capsules are one of the most common strengths available, representing a full gram packet divided into standard dosing. With 444 mg capsules, many people take one capsule daily regardless of exact weight, as this falls within the 150-300 mg range used in various protocols.

The 222 mg strength (half of 444 mg) suits lighter individuals or those starting with conservative dosing. Some protocols use doses up to 1000 mg a day. A published case report describes an 80-year-old woman with lung cancer who took 1 g a day on a three days on, four days off schedule for about a month and developed drug-induced liver injury (ALT 487 U/L), which resolved after she stopped (Yamaguchi et al., 2021).

Common Fenbendazole Dosing Protocols

Three protocols come up most often in online communities. None of them has been tested in a clinical trial. The first is continuous daily dosing at 150-222 mg per day without breaks. Users following this pattern typically take one 222 mg dose or a smaller measured amount from a 444 mg capsule.

The second common approach uses 222-300 mg daily for three consecutive days, followed by four days off. This creates a weekly cycle where you dose Monday through Wednesday, then resume the following Monday. The theory behind this pattern involves giving the body recovery time while maintaining consistent exposure.

The third protocol employs higher intensity cycles: 444-1000 mg daily for three to five consecutive days, followed by 10-14 days off before repeating. This aggressive approach mirrors some veterinary deworming schedules adapted for different purposes.

People who follow these protocols usually describe starting with the lowest-dose option. There is no clinical evidence that any of the three works better than the others, and a doctor should be involved before anyone tries them.

Daily Schedule and Timing Considerations

Fenbendazole is poorly absorbed from the gut, a point the 2024 Anticancer Research review discusses at length (Nguyen et al., 2024). People who take it usually take it with a meal that contains some fat, such as breakfast or dinner. How it behaves in the human body has not been well documented.

Timing consistency matters more than the specific hour you choose. Taking it at roughly the same time each day makes a cycling schedule easier to track. If you're on a three-days-on, four-days-off schedule, many people prefer starting their cycle on the same weekday to simplify tracking.

You can split larger doses if needed. Someone taking 444 mg daily could divide this into 222 mg twice daily, though most find once-daily dosing more convenient. There's no evidence that splitting provides superior results.

Avoid taking fenbendazole on a completely empty stomach if you experience nausea. While not strictly required with food like some medications, the presence of dietary fat helps with absorption and reduces the chance of mild gastric discomfort.

Fenbendazole Dosage Chart by Weight

Here is what the 1 mg per pound rule from online protocols works out to. This is arithmetic only, not a recommended dose:

Body Weight → Calculated Dose → Practical Dose with 444mg Capsules

• 100 lbs → 100 mg → 1/4 capsule or one 222mg capsule every other day
• 125 lbs → 125 mg → 1/3 capsule or 222mg daily
• 150 lbs → 150 mg → 1/3 capsule or 222mg daily
• 175 lbs → 175 mg → 1/2 capsule or one 222mg capsule daily
• 200 lbs → 200 mg → 1/2 capsule or one 222mg capsule daily
• 225 lbs → 225 mg → 1/2 capsule or one 444mg capsule every other day
• 250 lbs → 250 mg → just over 1/2 capsule, round to 222mg or 444mg depending on protocol

These calculations assume standard protocols in the 150-300 mg daily range. Higher-dose protocols (444-1000 mg) don't scale linearly with weight. Instead, they use fixed amounts regardless of body size, similar to how many pharmaceutical drugs work above certain weight thresholds.

Fenbendazole should not be given to children. Its safety in people has not been established at any body weight.

Converting Between Different Strengths

Fenbendazole comes in several strengths: 222 mg (common in single-dose packets), 444 mg (double packets), and bulk powder that you measure yourself. Converting between these forms requires basic math but can confuse people initially.

One 444 mg capsule equals two 222 mg capsules. If your protocol calls for 222 mg daily but you only have 444 mg capsules, you can take one capsule every other day to average 222 mg daily, or carefully open capsules and measure half portions.

Many users invest in a milligram scale (accurate to 0.01g) if they're working with bulk powder or want to measure precise partial doses from capsules. A scale that reads to 100 mg accuracy costs under $20 and removes guesswork.

The Wormiza 500mg formulation provides another option, though less common for human use protocols. Someone wanting 250 mg daily could take half of a 500 mg dose, which might be easier to measure than portions of 444 mg capsules.

When opening capsules to measure partial doses, store the remaining powder in a sealed container away from moisture. Fenbendazole powder remains stable at room temperature but degrades in humid conditions.

Ordering and Using Fenbendazole in the USA

In the United States, fenbendazole is not FDA-approved for human use and is only officially approved as a veterinary antiparasitic. This creates a unique situation where the compound is legal to purchase but is marketed for animal use. Many Americans obtain fenbendazole through veterinary suppliers or specialized online pharmacies.

SafeRxPills ships fenbendazole tablets for veterinary use to USA addresses, typically with delivery times of 10-14 business days for standard shipping. The medication arrives in sealed packaging with clear labeling of strength and quantity.

Prices in the US market vary significantly. A month's supply at 222 mg daily (approximately 6600 mg total) costs between $30-$60 depending on source and quantity purchased. Buying in larger quantities reduces per-dose cost. For detailed information about US-specific suppliers and regulations, see our guide on buying fenbendazole in the USA.

Veterinary fenbendazole is sold over the counter in the US for animals, so no prescription is involved; that does not make it approved for people. Some healthcare providers are becoming more familiar with fenbendazole use and may provide monitoring even if they don't formally prescribe it.

US users should verify that any fenbendazole they purchase lists the actual milligram content clearly. Some veterinary products list percentage concentration rather than total milligrams, which complicates dosing calculations. Tablet products such as Wormiza state the milligrams per tablet on the pack.

Factors That Affect Your Dosage

Several factors matter for anyone considering fenbendazole despite the lack of approval. Liver function tops this list. Fenbendazole undergoes hepatic metabolism, meaning people with compromised liver function may need reduced doses or extended time between cycles. Anyone with a history of liver disease should not take it without a doctor's advice.

Kidney function matters less than liver function, but people with significant renal impairment might experience altered drug clearance. There are no human data on kidney impairment.

Fenbendazole is broken down in the liver, so medicines that speed up or slow down liver enzymes could change its levels. This has not been studied in people, so anyone on regular medicines should check with a doctor or pharmacist first.

Age influences drug metabolism, though the effect on fenbendazole specifically hasn't been extensively studied. Older adults may be more exposed to liver effects; the published liver injury case above was in an 80-year-old. It should not be given to children.

Gastrointestinal conditions affect absorption. People with inflammatory bowel disease, chronic diarrhea, or malabsorption syndromes may not absorb fenbendazole as efficiently as those with healthy gut function. Some users in this category find that taking doses with extra fat (like a tablespoon of olive oil) improves absorption.

What to Monitor While Taking Fenbendazole

If someone takes fenbendazole anyway, regular blood tests are the main safeguard, particularly on extended protocols. Basic bloodwork every 8-12 weeks provides useful baseline data. This should include a complete blood count (CBC) and complete metabolic panel (CMP) that covers liver enzymes and kidney function.

Liver enzymes (ALT, AST) deserve specific attention. Case reports describe drug-induced liver injury after self-administered fenbendazole, including severe hepatocellular injury, with liver tests recovering after it was stopped (Yamaguchi et al., 2021; World Journal of Clinical Cases, 2026). Any rise in ALT or AST, or symptoms such as yellow skin or dark urine, means stopping it and seeing a doctor.

Blood counts are worth checking as well. Significant drops in WBC, particularly neutrophils, warrant stopping the medication and medical evaluation.

Physical symptoms to note include digestive changes (diarrhea, nausea, or abdominal pain), unusual fatigue, yellowing of skin or eyes (jaundice), or dark urine. These could indicate liver stress and require immediate medical attention.

Many people track subjective effects in a journal: energy levels, sleep quality, digestive comfort, and any other changes they notice. This creates a personal baseline that helps identify patterns or problems early.

If you're taking other medications regularly, similar to monitoring approaches for medications like metronidazole or ivermectin, maintaining awareness of potential interactions helps prevent complications.

This information is for educational purposes only and does not constitute medical advice. Consult with a qualified healthcare professional before starting any new medication or supplement regimen, especially if you have existing health conditions or take other medications.