Giardia: Causes, Symptoms, and Treatment Options

When you hear Giardia, a microscopic parasite that infects the small intestine and causes giardiasis. Also known as Giardia lamblia, it’s one of the most common causes of waterborne illness worldwide. It doesn’t need fancy conditions to survive—just dirty water, poor hygiene, or close contact with an infected person or animal. You don’t need to travel overseas to catch it. Backyard ponds, campsite streams, even poorly filtered tap water in some areas can carry it.

Giardia doesn’t always make you sick right away. Some people carry it for weeks without symptoms, while others get sudden, watery diarrhea, bloating, gas, and stomach cramps that last days or even weeks. Fatigue and weight loss often follow. It’s not usually life-threatening, but if left untreated, it can mess with your ability to absorb nutrients and leave you feeling drained for months. Giardiasis, the illness caused by Giardia infection, is often mistaken for a stomach bug or food poisoning—until tests confirm the parasite is to blame.

What makes Giardia tricky is how easily it spreads. Kids in daycare, hikers, travelers, and even pets can be silent carriers. If someone in your household has it, the risk to others is high unless you clean surfaces, wash hands thoroughly, and avoid sharing towels or utensils. Antiparasitic drugs, medications designed to kill parasites like Giardia are the standard treatment. Metronidazole and tinidazole are common, but not everyone tolerates them well. Alternatives like nitazoxanide are available, and doctors often adjust based on age, pregnancy, or other health conditions. The key? Don’t ignore symptoms just because they seem mild. A simple stool test can confirm it, and treatment works best when started early.

You won’t find a single article here that says "just drink more water" and call it a day. The posts below give you real, practical details: how to spot Giardia in kids versus adults, which treatments have the fewest side effects, what to do if meds don’t work, and how to prevent reinfection at home. You’ll also see how it connects to broader issues—like water safety, antibiotic resistance, and why some people keep getting it back even after treatment. This isn’t theory. These are the questions real patients and caregivers ask, and the answers that actually help.