Antiparasitic Medication for Humans

Antiparasitic medication for humans is medicine used for infections caused by parasites, and it is not one single drug: there are separate groups of medicines for parasitic worms, for one-celled parasites called protozoa, and for parasites that live on the skin. In the United States most antiparasitic medicines need a prescription, and a clinician usually confirms which parasite is involved before choosing one.

This page explains the main groups, how they differ from antibiotics, which ones are sold over the counter, and why a diagnosis usually comes first. It is general education, not medical advice.

What is an antiparasitic medication?

The CDC defines a parasite as an organism that lives on or in a host and gets its food from, or at the expense of, that host. MedlinePlus adds that parasites range in size from tiny one-celled organisms to worms that can be seen with the naked eye, and that some medicines are available to treat parasitic infections. Those medicines are antiparasitics.

The World Health Organization (WHO) uses the word antimicrobials for medicines that prevent and treat infections, and it lists antiparasitics as one group alongside antibiotics (for bacteria), antivirals (for viruses) and antifungals (for fungi). Each group is aimed at a different kind of organism, so an antibiotic is not a stand-in for an antiparasitic, or the other way around. Our page on whether ivermectin is an antibiotic explains that difference in more detail.

The three main types of parasites, and the medicines for each

The CDC sorts the parasites that cause disease in people into three main classes: helminths (worms), protozoa (one-celled organisms) and ectoparasites (organisms that live on the skin). Antiparasitic medicines follow the same lines, and a medicine made for one class is not used for the others.

Worms (helminths): anthelmintic medicines

Helminths are many-celled worms. The CDC says they are generally visible to the naked eye in their adult stage and, unlike protozoa, cannot multiply in the human body as adults. The groups that infect people include roundworms (such as pinworm, common roundworm, whipworm and hookworm) and flatworms (tapeworms and flukes).

Medicines for worm infections are called anthelmintics, which means anti-worm medicines. Some examples that MedlinePlus describes:

• Mebendazole is a prescription anthelmintic. The prescribing information for the brand-name mebendazole chewable tablet lists four labeled uses: pinworm, whipworm, common roundworm and hookworm. See what is mebendazole.
• Ivermectin is a prescription anthelmintic taken by mouth. The prescribing information for the brand-name ivermectin tablet lists two labeled uses: intestinal strongyloidiasis and onchocerciasis (river blindness). See what is ivermectin.
• Pyrantel pamoate is described by MedlinePlus as an antiworm medication. In the United States it is sold without a prescription, and the package sold that way is labeled for pinworm.
• Albendazole is a prescription anthelmintic. MedlinePlus lists its uses as certain tapeworm infections of the body's tissues.

Each anthelmintic's labeling names specific worms, and none covers every worm. For example, see which parasites mebendazole's labeling covers.

One-celled parasites (protozoa): antiprotozoal medicines

Protozoa are microscopic, one-celled organisms. The CDC explains that they can multiply inside the body, that the ones living in the intestine usually spread through contaminated food or water or person-to-person contact, and that the ones living in the blood or tissues are spread by insect bites, such as from mosquitoes or sand flies. Giardia, Cryptosporidium, Entamoeba and Plasmodium, the parasite that causes malaria, are all protozoa.

Protozoal infections use a different set of medicines from worm infections. Two examples MedlinePlus describes:

• Nitazoxanide is in a class MedlinePlus calls antiprotozoal agents. Its listed use is diarrhea caused by the protozoa Cryptosporidium or Giardia.
• Tinidazole is a nitroimidazole antimicrobial. Its listed uses include giardiasis and amebiasis, which are intestinal protozoal infections, as well as some infections that are not caused by parasites.

Malaria has its own group of medicines, which a clinician chooses based on the person and where they traveled. Neither ivermectin nor mebendazole is an antiprotozoal medicine. Both are labeled for worm infections only.

Skin parasites (ectoparasites)

The CDC uses the word ectoparasites for organisms such as ticks, fleas, lice and mites that attach to or burrow into the skin. The two that most often need treatment are lice and the scabies mite. MedlinePlus says head lice treatments include over-the-counter and prescription shampoos, creams and lotions, and that several lotions are available for scabies. These products are applied to the skin or hair, and a pharmacist or clinician can help you choose one. Get It Prescribed does not treat lice or scabies.

Which antiparasitic medicines are sold over the counter?

Only a few. In the United States, the main antiparasitic you can buy off the pharmacy shelf for a worm infection is pyrantel pamoate, labeled for pinworm; our page on pinworm medicine: OTC or prescription compares it with mebendazole. Some head lice products are also sold over the counter.

Most other antiparasitic medicines for people, including mebendazole and ivermectin tablets, are prescription-only in the United States. That means a licensed clinician has to review your situation before one can be prescribed.

Why a diagnosis usually comes first

Because each antiparasitic medicine is aimed at particular parasites, the first question is which parasite, if any, is causing the problem. Common complaints such as belly pain, diarrhea, bloating and itching have many causes besides parasites. A clinician may suggest:

• A stool test for parasites, which looks for eggs, larvae or parasites in a stool sample
• A pinworm tape test, which collects eggs from the skin around the anus first thing in the morning
• Blood tests or other checks for certain infections

If you are not sure which worm you might have, our guide to intestinal worms in adults walks through the common ones and how each is caught.

See a clinician in person, rather than online, if you have blood in your stool, severe or worsening belly pain, a high fever, a fever after recent travel abroad, signs of dehydration, a weakened immune system, or you are pregnant or breastfeeding.

Antiparasitic medication through Get It Prescribed

Get It Prescribed offers two antiparasitic medicines, both for their labeled uses only: ivermectin and mebendazole. An independent, licensed provider reviews your information and makes their own decision. No prescription is guaranteed, and the provider may recommend testing or an in-person visit instead.

The medicines dispensed through Get It Prescribed are compounded preparations made by a licensed compounding pharmacy. They are not FDA-approved, the FDA has not reviewed them for safety, effectiveness or quality, and they are not generics of, or substitutes for, the brand-name products.

The cost is a one-time $50 provider consultation fee, plus $3.00 per ivermectin tablet or $3.50 per mebendazole capsule if a prescription is issued, with the quantity decided by the provider. The service is for adults and is available in all 50 states and the District of Columbia; some states require a live phone or video visit, which you can check on the availability page. You can see every step on how it works.

This article is general education, not medical advice. It does not replace an evaluation by a licensed clinician who knows your history.

Related questions

Is there an over-the-counter antiparasitic for humans?

Yes, but only a few. In the United States, pyrantel pamoate is sold without a prescription and is labeled for pinworm, and some head lice treatments are sold over the counter. Most other antiparasitic medicines for people, including mebendazole and ivermectin tablets, need a prescription.

Is ivermectin an antiparasitic?

Yes. MedlinePlus places ivermectin in the anthelmintic (anti-worm) class, which is one kind of antiparasitic medicine. Its labeled uses are intestinal strongyloidiasis and onchocerciasis. It is not an antibiotic, an antiviral or an antifungal.

What is the difference between an antiparasitic and an antibiotic?

They are aimed at different organisms. Antibiotics are for infections caused by bacteria, while antiparasitics are for infections caused by parasites such as worms and protozoa. The WHO lists them as separate groups of antimicrobial medicines, and one is not a substitute for the other.

Does one antiparasitic medicine treat every parasite?

No. Each medicine's labeling names specific parasites. Medicines for worms (anthelmintics) are different from medicines for one-celled parasites (antiprotozoals) and from the products used for lice and scabies, so the parasite has to be identified first.

Do I need a test before taking an antiparasitic medicine?

Often, yes. A clinician usually confirms the infection first, for example with a stool test or, for pinworm, a tape test, because the right medicine depends on the parasite. Whether a test is needed in your case is the clinician's decision.

Sources

• CDC: About Parasites — the definition of a parasite and the three main classes that cause disease in people: protozoa, helminths and ectoparasites.
• MedlinePlus: Parasitic Diseases — consumer overview of parasites, how people get them, and that medicines are available for some parasitic infections.
• WHO: Antimicrobial resistance fact sheet — antimicrobials as a family that includes antibiotics, antivirals, antifungals and antiparasitics.
• MedlinePlus: Mebendazole — consumer drug information; mebendazole is in the anthelmintic class.
• MedlinePlus: Ivermectin — consumer drug information; ivermectin is in the anthelmintic class.
• MedlinePlus: Pyrantel — consumer drug information for the antiworm medicine sold over the counter for pinworm.
• MedlinePlus: Albendazole — consumer drug information; listed uses are certain tapeworm infections.
• MedlinePlus: Nitazoxanide — consumer drug information; an antiprotozoal agent.
• MedlinePlus: Tinidazole — consumer drug information; listed uses include giardiasis and amebiasis.
• MedlinePlus: Head Lice — over-the-counter and prescription treatments for head lice.
• MedlinePlus: Scabies — the scabies mite and the lotions used to treat it.
• DailyMed: ivermectin tablet prescribing information — labeled uses of ivermectin tablets.
• DailyMed: mebendazole chewable tablet prescribing information — labeled uses of mebendazole.
• FDA: Compounding and the FDA — Questions and Answers — what compounded preparations are and how they are regulated.