Can Fenbendazole Be Taken on Empty Stomach?

Fenbendazole is an antiparasitic drug commonly prescribed to treat parasitic worm infections in pets. With the rise of fenbendazole searches on the internet, some curious individuals even ask how fenbendazole should be taken, including the question if fenbendazole can be taken on an empty stomach.

Fenbendazole can be given orally with or without food. While some studies show that fenbendazole can be dosed without regard to food, issues around fenbendazole administration in individuals still remain. Most importantly, fenbendazole’s safety and efficacy have not been evaluated for use in humans; fenbendazole is not approved for use by the FDA.

What Is Fenbendazole?

Fenbendazole is a benzimidazole antiparasitic drug used to eliminate infections with roundworms, hookworms, whipworms, and tapeworms. In veterinary medicine, fenbendazole is FDA approved for the treatment of gastrointestinal parasites in certain animal species.

There are fenbendazole products that are approved for mixing with food of a small quantity.

As these product instructions are designed specifically for animals, they should not be used for humans.

Can Fenbendazole Be Taken Without Food?

Fenbendazole is absorbed in animals regardless of food being present. However, the amount of fenbendazole that is absorbed is likely to be different with food present or absent.

There was one study published in Research in Veterinary Science, that evaluated the bioavailability of fenbendazole in six dogs. The researchers determined that the dose of fenbendazole in food was absorbed much better than when the same dose of fenbendazole was given to the dogs without food.

Taking fenbendazole without food does not necessarily mean the drug will not be absorbed. Food can just change the quantity that makes it to the systemic circulation.

What Does Food Do to Fenbendazole Absorption?

The manipulation of food in the stomach and the condition of the intestines by food can slow or increase the absorption of a number of oral medications. This is through changing intestinal movements, the secretion of intestinal fluids, the transport of intestinal blood, and other processes.

Results obtained from laboratory studies on animals have been variable with regard to fenbendazole absorption and also to the condition of the feeding status.

In dogs, one study reported that with food, the apparent bioavailability was greater than with an empty stomach. Another study reported the same finding regarding the apparent bioavailability of fenbendazole.

Research studies in horses have reported the opposite finding. In those studies, an absence of food resulted in the greater exposure to the benzimidazole compound.

These findings illustrate that the results that were obtained from the research studies for one species of animal cannot be extrapolated to humans for either dosing or recommendations on food.

Does Fenbendazole Work Better With Food?

There is, to date, no published human data to suggest that if fenbendazole is taken with food it significantly alters its absorption. However, there is published data from research studies that have included animals to suggest that food, to some degree, alters the absorption of fenbendazole.

It would not be accurate to suggest that fenbendazole absorption is improving by prescribing that it be taken with food. A number of factors, including the feeding status of the animal, the type of food, the time of feeding, the animal species, the formulation, and the dose, can all alter the absorption of a drug.

From a safety perspective, it is prudent to follow the instructions on the product label for a veterinary product or the instructions given by a veterinarian.

What About Taking Fenbendazole With a Fatty Meal?

You may have heard that fenbendazole should be taken with a fatty meal. Based on the evidence that exists, we should not add this to the standard recommendations.

For example, one of the study cited, which studied dogs, looked at food that contained varying amounts of fat. In that study, researchers found that food, in general, increased bioavailability compared to an empty stomach. However, varying the amount of fat in the food had minimal to no impact on relative bioavailability.

Additional research that included horses found that food effects vary across species.

Based on this, there is no established, evidence-based rule for everyone to take fenbendazole with a fatty meal.

What if Fenbendazole Causes Stomach Issues?

Gastrointestinal upset is common with a number of medications. When an animal receiving fenbendazole develops vomiting, diarrhea, or other atypical signs, the owner should contact the veterinarian.

The FDA has also reported adverse events concerning prolonged, extra-label fenbendazole use in dogs. As of October 20, 2023, the agency had received 12 reports involving bone marrow hypoplasia or pancytopenia in dogs treated beyond the approved duration.

This is a good reminder that pain is always associated with inappropriate use of a medication, even if it is commonly used in veterinary practice.

Can You Take Fenbendazole on an Empty Stomach?

This question needs clarification.

Fenbendazole is not approved by the Food and Drug Administration for human use, and there are insufficient clinical data to define the appropriate human dose, treatment regimen, or the impact of food on administration.

So, even though there are studies on how fenbendazole behaves with and without food in animals, that shouldn’t be used as a guide for humans to self-medicate.

For those with a particular health concern, it’s best to speak with a doctor rather than the veterinarian or online instructions to find your own dosage.

Human Research and Fenbendazole

Since researchers other than those in the veterinary sciences are exploring its potential uses, fenbendazole may have greater potential than previously thought. Some studies describe its possible uses to include cellular phenomena or oncological models.

Even if interactions between fenbendazole and other substances have been studied in the laboratory or in animals, the published results cannot considered evidence that fenbendazole is useful for human treatment of any illness or disease.

The absence of clinical trials is particularly important when evaluating issues regarding food, duration of treatment, and possible adverse drug reactions.

Frequently Asked Questions

Can fenbendazole be taken on an empty stomach?

Studies on animals show that fenbendazole can be given on an empty stomach, however, the absorption of fenbendazole may be altered by food. There are no definitive guidelines for humans.

Does food increase the absorption of fenbendazole?

Studies done on dogs show that fenbendazole absorption is increased by food compared to an empty stomach. Variability is common when studying different species of animals.

Does fenbendazole always need to be taken with food?

Not necessarily. Most veterinary medications are give with instructions for food as part of the label. For example, Panacur-C for dogs indicates that the medication be mixed in with a very small amount of food.

Is fenbendazole made for humans?

Fenbendazole is veterinary medicine and is not permitted for human use in the United States.

Final Thoughts

Fenbendazole can absorbed when given without food. However, studies have shown that food can affect its bioavailability. Studies that have looked at dogs have shown that fenbendazole is absorbed better if given along with food. Studies that have looked at other animals have shown results that are contrary to this.

As the studies that have shown these results come from the veterinary field, they cannot  used to develop a dosing regimen for humans. Fenbendazole still does not have FDA approval for human consumption, and there is limited clinical research on the safety and efficacy of fenbendazole in humans and its pharmacokinetics.

You must always follow the drug label or the instructions of your veterinarian if you plan to give this drug to your pet. You must not follow any of the instructions that you may find online.