Giardiasis Symptoms: What to Watch For and How It’s Treated

When you have a giardiasis, a parasitic infection caused by Giardia lamblia that affects the small intestine. Also known as beaver fever, it’s one of the most common causes of travel-related diarrhea and can show up even if you didn’t leave town. It doesn’t come from bad food alone—it’s usually from drinking water that’s been contaminated with feces, whether from hikers, animals, or faulty sewage systems. You can catch it from swimming in lakes, using untreated well water, or even from person-to-person contact in daycare centers or households.

Most people don’t realize they’re infected until symptoms hit. The big ones? diarrhea, foul-smelling, greasy stools that float and don’t sink, stomach cramps, bloating, gas, nausea, and extreme fatigue. Unlike regular stomach bugs, giardiasis doesn’t always cause fever. Instead, it lingers for weeks—sometimes months—if untreated. Kids and older adults are more likely to get seriously dehydrated, and some people carry the parasite without symptoms but still spread it. It’s not just a summer problem; outbreaks happen year-round, especially after heavy rains or flooding that overwhelms water systems.

What makes giardiasis tricky is that it mimics other gut issues. You might think it’s food poisoning, lactose intolerance, or IBS. But if your diarrhea lasts more than a week, especially after camping, hiking, or traveling, it’s worth getting tested. Doctors diagnose it by checking stool samples—sometimes multiple times—because the parasite isn’t always present in every sample. Treatment is usually a short course of antibiotics like metronidazole or tinidazole, which clear the infection fast in most cases. But prevention matters more: boil water if you’re unsure of its safety, wash hands after using the bathroom or changing diapers, and avoid swallowing water while swimming.

Below, you’ll find real, practical posts that dig into how giardiasis connects to other health topics—from drug interactions in treatment, to how dehydration affects recovery, to how over-the-counter remedies can help or hurt. Whether you’re dealing with symptoms now or just want to know what to watch for next time you’re out in the wild, these guides give you the facts without the fluff.