What Is the Best Antiparasitic Medication?

Antiparasitic drugs are prescribed based on the specific parasite and type of parasite. These may include antiprotozoal medications, anthelminthic medications, and ectoparasiticide medications.

There are several classes of antiparasitic medications that cover a broad range of diseases caused by parasites. Parasites are microorganisms that live on or inside another organism (the “host”) and benefit at the expense of their host. Parasitic infections are more common in tropical areas, but they can also occur in subtropical and temperate regions. 

The best antiparasitic drug varies, depending on the specific parasite and type of parasite. There are several types of parasites known to cause disease in humans, including: 

• Protozoa
  • Unicellular organisms that often infect immunocompromised patients such as those with acquired immune deficiency syndrome (AIDS)
  • Infection can range in severity from asymptomatic to fatal
• Helminths
  • Parasitic worms
  • Transmitted by accidental ingestion, skin penetration, a vector bite, or consumption of the host as food
• Ectoparasites
  • Live externally on the skin of hosts
  • Includes organisms such as mites, lice fleas, ticks, and bedbugs

Commonly used antiprotozoal medications include: 

• Antimalarials
  • Chloroquine 
  • Oral quinine (used during pregnancy)
  • Primaquine, mefloquine, atovaquone-proguanil, and doxycycline are used to prevent malaria 
• Antibabesial agents
  • Atovaquone and azithromycin
  • Clindamycin plus quinine for severe disease
• Antiamoebic agents
  • Paromomycin sulfate
  • Metronidazole
  • Tinidazole
  • Chloroquine is used an adjunct therapy for the management of liver abscesses
• Antigiardial agents
  • Metronidazole
  • Tinidazole
  • Albendazole
• Trypanocidal agents
  • Nifurtimox
  • Benznidazole 
  • Pentamidine 
  • Eflornithine 
  • Melarsoprol 
• Antileishmanial agents
  • Sodium stibogluconate 
  • Pentamidine
  • Amphotericin B 
  • Paromomycin 
• Anti-toxoplasma agents
  • Sulfadiazine combined with pyrimethamine 
• Antitrichomoniasis agents
  • Metronidazole 

Commonly used anthelminthic medications include: 

• Anticestodal drugs
  • Praziquantel
  • Albendazole
• Antinematodal drugs
  • Praziquantel
  • Albendazole
  • Diethylcarbamazine (available through the CDC Drug Service) 
  • Ivermectin 

Commonly used ectoparasiticide medications include: 

• Antiscabietic agents
  • Lindane
  • Permethrin
  • Ivermectin
• Pediculicides
  • Permethrin 
  • Pyrethrins
  • Malathion
  • Ivermectin

Side effects of antiparasitic medications depend on the medication used. 

Side effects of antiprotozoal medications vary depending on the specific medicine used and may include:

• Gastrointestinal (GI) effects
  • Nausea
  • Vomiting
  • Loss of appetite
  • Abdominal pain and/or cramps
  • Diarrhea
• Headaches
• Insomnia
• Fever
• Itching 
• Dizziness
• Behavioral disturbances
• Rash
• Irregular heartbeats (arrhythmias)
• Other cardiac conduction abnormalities
• Photosensitivity 
• Vaginal yeast infection (candida vaginitis)
• Metallic taste in the mouth
• Dry mouth
• Hair loss 
• Increased liver enzymes 
• Numbness and tingling of extremities
• Seizures
• High or low blood pressure (hypertension or hypotension)
• Shortness of breath
• Muscle and/or joint pain

Side effects of anthelminthic medications vary depending on the specific medicine used and may include:

• GI disturbances such as nausea, vomiting, abdominal cramps, and diarrhea
• Skin rash
• Muscle and/or joint pain
• Fever
• Dizziness
• Headache
• Weakness
• Drowsiness
• Increased liver enzymes

Side effects of ectoparasiticides vary depending on the specific medicine used and may include:

• Skin itching, burning, and stinging
• Nervous system toxicity and blood toxicity

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about the side effects of the specific drug you are prescribed.