Yes, humans can and do take deworming medication. Several antiparasitic drugs are specifically formulated and approved for human use, and the World Health Organization recommends routine deworming for at-risk populations worldwide. The important distinction is between medications made for people and products made for animals, which are not interchangeable despite sometimes containing the same active ingredient.
Human-Approved Deworming Medications
Multiple antiparasitic drugs are approved for human use. The most commonly prescribed include albendazole, mebendazole, ivermectin, and praziquantel. Each targets different types of parasites. Albendazole and mebendazole work against roundworms, hookworms, and whipworms by disrupting the parasites’ ability to absorb glucose and build cellular structures, essentially starving them. Praziquantel treats tapeworms and flukes. Ivermectin handles a different set of parasites, including threadworm (Strongyloides) and certain external parasites like scabies.
One option is even available without a prescription. Pyrantel pamoate, sold over the counter in the United States, treats pinworms and roundworms. It comes as a capsule or liquid, taken as a single dose, with a repeat dose two weeks later for pinworm infections. It can be taken with food, juice, or milk.
Why Animal Dewormers Are Dangerous for People
The search behind this question often stems from the idea of using veterinary deworming products. This is where real risk enters the picture. Animal and human formulations of the same drug differ in concentration, inactive ingredients, and quality standards. The FDA has evaluated veterinary products only for safety in the specific animal species listed on the label, not for humans.
During the COVID-19 pandemic, poison control centers saw a surge in people taking veterinary ivermectin. A study of these cases found that patients who took veterinary formulations ingested much larger doses than those using prescription tablets and experienced higher rates of altered mental status. Clinical effects included neurotoxicity in 30 patients, gastrointestinal symptoms in 14, and musculoskeletal problems in 7. Many developed rapid-onset neurological symptoms after taking large single doses or large daily doses over several days. The concentration in a horse paste, for example, is calibrated for an animal weighing over 1,000 pounds, making accurate human dosing nearly impossible.
Signs of a Parasitic Infection
Parasitic infections produce different symptoms depending on the type of worm involved. Hookworm often causes weakness, paleness, abdominal pain, and diarrhea, all related to the anemia it creates. This is particularly concerning in young children and pregnant women. Roundworm (Ascaris) can cause abdominal pain and coughing, and heavy infections may lead to intestinal blockage. Whipworm may cause bloody stools, anemia, and in rare cases, rectal prolapse.
Threadworm (Strongyloides) typically presents with abdominal complaints, nausea, diarrhea or constipation, dry cough, and skin rashes. Giardia, a protozoan parasite rather than a worm, causes chronic diarrhea, poor appetite, weight loss, bloating, and gas. Many parasitic infections, however, produce no obvious symptoms at all. An elevated count of a specific white blood cell type called eosinophils, found on a routine blood test, is sometimes the only clue.
How Deworming Treatment Works
Most human deworming treatments are short. A single dose or a brief course of medication is typical. Albendazole and mebendazole, the two most widely used drugs, work by blocking the parasites’ ability to build and maintain their internal cellular scaffolding and to take in glucose. Without energy, the worms weaken, detach from the intestinal wall, and are expelled naturally.
This process takes longer than most people expect. Research tracking roundworm expulsion after albendazole treatment found that it takes up to 10 days for all adult worms to be passed, with roughly 20% expelled between days 7 and 10. Parasite eggs may still appear in stool samples at day 7, but by day 14, egg counts typically drop to zero. For this reason, follow-up testing is usually done at least two weeks after treatment. Treatment is not always 100% effective on the first round, and a repeat course is sometimes necessary if symptoms or lab markers persist.
Side Effects of Human Dewormers
At standard doses, human deworming medications are well tolerated. Mebendazole at its usual dosing range causes minimal adverse effects. The most common complaints are transient diarrhea and abdominal pain, which tend to occur when a heavy worm burden is being expelled rather than as a direct drug reaction. Nausea, headache, and dizziness have been reported occasionally.
Rarer side effects include skin rash, temporary changes in liver function tests, and mild drops in blood cell counts. These are uncommon enough that the WHO recommends mass deworming programs in endemic areas without requiring individual diagnosis first, a reflection of how favorable the risk-benefit ratio is for these drugs.
Pregnancy and Deworming
Timing matters for some populations. The FDA previously classified ivermectin as a pregnancy category C drug, meaning animal studies showed potential fetal harm and no adequate human studies exist. A systematic review in The Lancet Global Health concluded there is insufficient evidence to determine ivermectin’s safety during pregnancy, and deworming campaigns are advised to make extra efforts to avoid inadvertently treating pregnant women.
The WHO does include pregnant women in its deworming guidelines, but only during the second and third trimesters and using specific medications considered safer during pregnancy. Women of reproductive age and breastfeeding women are also listed among priority groups for periodic deworming in regions where soil-transmitted parasites are common.
Who Gets Dewormed and How Often
In many parts of the world, deworming is routine public health practice. The WHO recommends periodic preventive treatment for preschool children, school-age children, women of reproductive age, and adults in high-risk occupations like tea picking or mining in areas where soil-transmitted parasites are endemic. The goal is not necessarily to eliminate every worm but to keep the parasite burden low enough to prevent serious health consequences like anemia, malnutrition, and organ damage.
In the United States and other high-income countries, parasitic infections are less common but far from nonexistent. Pinworm is widespread among school-age children. Strongyloides persists in parts of the rural South. Immigrants and refugees may carry infections acquired abroad. In these settings, deworming is diagnosis-driven rather than routine, meaning treatment follows testing that confirms an infection is present.