Alongside insufficient nutrition and lack of access to clean water, parasitic infections are among the biggest challenges facing the world’s expanding population today, particularly in underdeveloped countries. The most prevalent parasitic infections worldwide are toxoplasmosis, hookworms, ascariasis, and trichomoniasis. Let us look closer at parasitic infections, their symptoms, how they affect people, and which ten medicinal drugs are considered the most effective treatments for diseases caused by parasites.

What Are Parasitic Infections?

A parasite is an organism that resides in or on another organism – the host – and draws sustenance from it. Parasites need their hosts for the survival and multiplication of their species. When a parasite invades the human body, grows, and replicates there, it starts interfering with major organ systems, causing an infection. Some of these infections cannot measurably affect the host or do much damage to their health. Some others – malaria, leishmaniasis, and trypanosomiasis – can kill the carrier if they go untreated.

What Are the Main Symptoms of Parasitic Infections?

To treat a parasitic infection effectively, doctors need to spot and recognize its symptoms in time, which can be challenging since many of these diseases are asymptomatic or have mild symptoms that can be confused with other more widespread illnesses. However, even though the signs of a parasitic infection vary greatly, depending on the organism, there are a few indications that can tell a person it is time to get checked for parasites. Here are some of the most characteristic ones:

  • Abdominal pain and cramps
  • Nausea and vomiting
  • Recurrent diarrhea
  • Bloating and excessive gas
  • Weight loss and lack of appetite
  • Dehydration
  • Swollen lymphatic nodes
  • Skin problems
  • Muscular and joint pain
  • Fatigue
  • Anemia
  • Flu-like symptoms
  • Returning yeast infections
  • Apathy and depression.

Since most of these symptoms are not exclusive to parasitic infections and can often point to other ailments like GI problems or influenza, it is crucial for patients to see a licensed doctor and have their diagnosis confirmed before starting any drug treatment.

What Causes a Parasitic Infection?

The three most common types of organisms that cause a parasitic infection in people are:

  • Protozoa (single-celled organisms) – giardia, leishmania, cryptosporidium.
  • Helminths (gut worms) – tapeworms, roundworms.
  • Ectoparasites (pathogenic organisms living outside the host) – fleas, ticks, lice.

Depending on the type, these parasites infect the host in different ways. For example, the infections they cause can spread through contaminated water, food, waste, soil, and blood or be transmitted sexually. Some others affect people via disease-carrying insects.

Top-10 Most Efficient Antiparasitic Drug Treatments

Here are the top-10 anti-parasite medications that modern medicine trusts the most:

Antimalarial agents

It is a whole arsenal of drugs designed to prevent and treat malaria. The most commonly used medications in this group are amodiaquine, proguanil, chloroquine, mefloquine, quinacrine, primaquine, and quinine. To achieve the best therapeutic efficacy, travelers should start taking these antimalarial agents before entering a malaria-stricken area and continue the treatment course for several weeks after their return from it.


Metronidazole is at the core of therapy for many protozoan infections, such as giardiasis, trichomoniasis, and amebiasis. This antibiotic and antiprotozoal drug works by stopping the growth of bacteria and parasites and can be combined with other meds to produce a more powerful effect (e.g., for amebiasis treatment, metronidazole is coupled with a luminal agent to fully eradicate the intestinal parasite.). More information about this medication:


One of the most trusted and frequently used antiparasitic medications worldwide, ivermectin is an FDA-approved drug for treating the filarial nematode Onchocerca volvulus infection and intestinal strongyloidiasis. If prescribed off-label, ivermectin can also be effective against pinworms, scabies, lice, and certain whipworm and roundworm infections. To learn more about how Stromectol (Ivermectin) works to kill parasites and who can use it, visit informational page

Pyrantel Pamoate

Pyrantel is a popular anthelmintic medication prescribed for the treatment of a wide range of parasite-caused worm infections, including ascariasis, pinworms, hookworms, nematodes, and Trichinella type roundworms. Since the drug has no systemic absorption, it is only efficient against worms living within the host’s intestinal tract.


This broad-spectrum anthelminthic drug is primarily approved for treating neurocysticercosis and echinococcosis, but can also be used off-label for killing roundworms, such as ascariasis, enterobiasis, and hookworms. Albendazole may have some potentially severe side effects like bone marrow suppression and hepatic inflammation, which is why it should be taken in strict accordance with the doctor’s recommendations.


Mebendazole is a broad-spectrum deworming agent helpful for most nematode infections, including Ascaris roundworms, hookworms, guinea worms, echinococcosis, and giardiasis. Since mebendazole is slow in destroying parasites, it, alone, may not be sufficient to cope with heavy infestations. To avoid having worms migrate outside the GI tract, mebendazole is often coupled with piperazine that slows the parasites and facilitates their removal from the host’s body. Read guide to Mebendazole


This potent broad-spectrum antiparasitic and antiviral medicine helps fight infections caused by a variety of protozoa and helminths. Nitazoxanide is an effective first-line anti-parasite treatment of cryptosporidiosis and giardiasis in adults and children with a normal immune response.


Praziquantel helps with a majority of tapeworm infections, such as cysticercosis, opisthorchiasis, schistosomiasis, clonorchiasis, and echinococcosis. The drug causes spasms and paralysis of the worm’s muscles. Unable to move and consume nutrients, it quickly dies of starvation and is removed from the host’s body with feces.


Miltefosine efficiently rids the person from leishmaniosis and some infections caused by free-living protozoa, including one of the world’s most dangerous brain-eating amoeba Naegleria fowleri. Being highly embryo- and fetotoxic, the use of Miltefosine is strictly contraindicated for pregnant women. The drug works by damaging the parasite’s membrane integrity and disrupting its mitochondrial function.


The drug treats intestinal infections caused by tapeworms – taeniasis, diphyllobothriasis, and hymenolepiasis – but has no effect against roundworms or pinworms. Niclosamide prevents tapeworms from absorbing glucose and inhibits their anaerobic metabolism.