Answer:
Short term:
Diarrhea. Gas. Foul-smelling, greasy stools (poop) that tend to float.
Long term:
Occasionally, people with giardiasis will have long-term complications such as reactive arthritis, irritable bowel syndrome, and recurring diarrhea that can last for years. Among children in particular, severe giardiasis may delay physical and mental growth, slow development, and cause malnutrition.