Generally, Flagyll, Metronidazole and Panacur are often used for Giardia, and repeated again in
2 weeks if the symptoms
have not subsided.
2001, Flagyll (Metronidazole) appeared effective in only about 60% of the cases. "Currently, some vets feel the effectiveness of Flagyl (Metronidazole) is down to 40%. Known side effects of Flagyl are nausea, disorientation, yeast growth, liver failure depression, regurgitation, and nerve damage".