I think it is time to discuss and deal with the growing concern that 222mg of Fenbendazole could seriously damage the liver. This concern seems to take on a life of its own as non-scientists try to decipher anything and everything they seem to find on the internet. Once again, I am not a doctor and I am not a scientist. BUT, I have done about as much research as any non-scientist could possibly perform and this is what I believe to be the truth:

1. First of all, the original research that concluded Fenbendazole could possibly cause liver problems was, in my opinion, a bogus study and conclusion. Why? Because the dosages in mice and birds used to come to that conclusion were approximately 100x in equivalency.

It is funny to me, in the internet rumor mill, how one tiny piece of information can be blown into full-on panic and concern.

2. There is subsequent research on Fenbendazole (see below) and the Johns Hopkins human clinical trials ongoing on the sister drug Mebendazole. In both cases, MUCH HIGHER doses than I am recommending were shown to be safe taken long term. I will be interested to see the different trial results, but in one trial, they are dosing 500mg, 3x a day for a total of 1,500mg per day. In my non-scientist mind, they wouldn’t even attempt 1,500mg per day if they didn’t believe that might be at the edge of the margin of safety. Nevertheless, compared to 222mg/day, it is “my opinion” that the safety should be clear to even a non-scientist. I have read that the scientists at JHU believe 300mg per day long term is safe.

Research on goats, quail and rats

Comparative studies on the effect of fenbendazole on the liver and liver microsomal enzymes in goats, quail and rats.

Department of Physiology and Pharmacology, School of Veterinary Medicine, Tuskegee University, AL 36088.


To compare the effect of fenbendazole on the liver and liver microsomal mono-oxygenases of goats, quail and rats, an oral dose of 25 mg/kg was administered to the animals daily for 9 consecutive days. On the tenth day, blood samples and livers were collected from both the control and the treated animals for preparation of serum and microsomes respectively. Determination of the activities of sorbitol dehydrogenase (SDH, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum samples showed that there was no significant increase in the activities of these enzymes in the treated animals as compared to their corresponding controls, suggesting no liver damage. Similarly, no significant difference in the amount of microsomal cytochrome P-450 was found between the control and the treated animals of the same species. Compared to their respective controls, the activities of microsomal benzphetamine N-demethylase and aniline hydroxylase were almost unchanged in the treated goats and rats. The results indicate that fenbendazole is not liver toxic to goats, quail or rats at a dose rate of 25 mg/kg.

In a 150 lb human, this would equate to 1,700mg per day versus the 222mg per day per my protocol (a 120 lb woman would equate to 1,350mg vs 222mg recommended here.)

3. Malignancy in the liver is a wholly different subject matter than effects of Fenben on liver function, and the two should not be confused. Many people are having success with tumors in the liver without effecting the liver enzymes.

4. Of course anyone with a preexisting condition in the liver should be careful and have their blood checked more often than most.


5. As hundreds of people have now taken this drug for extended periods of time, we have learned a lot that I can now pass on.

A. “Many people, to my surprise and without my knowledge, have chosen to self dose at much higher levels than I originally recommended, not only in mg/day but also in number of consecutive days. I love it that people can be so brave and bold as to experiment with their own bodies, but it shows you that when people are given “no hope” by traditional methods, their risk tolerance somehow takes a huge leap of faith. And these people that self dosed at much higher levels have shown amazing results, while not reporting any additional or unusual side effects”

B. Most people are now jumpstarting the process with 7 days a week for the first 2-4 weeks, while a few people have jumpstarted with 7 days a week long term. None of those people have reported any new or unusual or added side-effects.

C. Many people are self administering at higher than 222mg per day, and to my knowledge, none of those people have reported any new or unusual or added side effects.

D. There have been a few people report elevated liver enzymes, so everyone needs to decide for themselves their dosage increases over the original recommendation, and everyone needs to decide for themselves the level of increased blood work for peace of mind.

With my usual disclaimer of “I am not a scientist or doctor”, I believe it is time for me to state the following:

Many people have successfully jumpstarted for 3 weeks at 7 days a week, and many people have successfully increased the daily intake from 222mg to 2x, 3x and 4d that level. While I am not recommending any specific “higher dosage”, I think the evidence from many people indicates each individual should make their own decision on higher dosages and consider what is best for them. At the end of the day, I believe it is what each individual can tolerate, but I believe most people can probably tolerate more than 222mg 3 days a week.

July 22,2020 Update

I now recommend people take the regimen 7 days a week and not 3 on and 4 off. Please keep an eye on your liver enzymes and only go back to 3 days a week if necessary