Giardiasis is among the most prevalent protozoan infections around the globe infecting various species of mammals, birds, reptiles, amphibians, and humans. Among all the species of Giardia, only Giardia lamblia (assemblages A and B) have high zoonotic importance. It is an enteric disease marked by dysentery, abdominal cramps, perfused diarrhea, and anorexia. The giardiasis is majorly controlled by metronidazole, which plays a primary role in the control. The reports of resistance, ecotoxicity, and side effects of this drug necessitate the need for an alternative for the control of this disease; among all the alternatives, phytochemicals are the most promising substance to be used for future anti-giardiasis drug development. Plant preparations containing simple phenolics, alkaloids, saponins, flavonoids, and vitamins have been recently used by researchers. These drugs have been proven effective because of several direct and indirect mechanisms. Simple phenolics easily penetrate the cell of Giardia and disturb energy synthesis, flavonoids destroy the enzymatic process, and alkaloids disturb glycolysis. The vitamins alter the cell energy primarily. Because of these actions, they can be used for control of giardiasis. However, their pharmacological interactions and clinical toxicity studies are needed for their future use.