Name two standard antifungal or antiparasitic drugs used to treat Giardia infections.

• A. Albendazole and Mebendazole
• B. Nitazoxanide and Albendazole
• C. Metronidazole and Tinidazole
• D. Ivermectin and Diethylcarbamazine

Answer: (C)

Giardia infections respond best to drugs that specifically target anaerobic protozoa. The two standard drugs in this category are metronidazole and tinidazole. Both are nitroimidazole antiparasitics that become activated inside Giardia to form reactive compounds, which damage the parasite’s DNA and other vital molecules, leading to death. Metronidazole is usually given over several days, while tinidazole can be given as a single-dose or shorter course, offering convenient options with strong efficacy. These drugs have long-standing clinical use, well-established effectiveness, and good tolerability, making them the go-to first-line therapy for giardiasis.

Other choices either target helminths rather than Giardia (albendazole, mebendazole; ivermectin, diethylcarbamazine) or are considered alternatives rather than standard first-line therapy (nitazoxanide).