How to Treat Giardiasis

Medically reviewed by Luba Lee, FNP-BC, MS

Last Updated: September 27, 2024 Fact Checked

Experts agree that giardiasis, a common parasitic infection, is typically contracted by drinking contaminated water, though you could also catch it from food or person-to-person contact. You may have giardiasis if you experience abdominal pain, nausea, bloating, and watery diarrhea for a week or longer. Research suggests that most people with giardiasis recover in 2 to 6 weeks, but you may be able to shorten your recovery with medication.^{[1]
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Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services

Go to source} Although you might be able to treat your symptoms at home, it's best to see your doctor if you suspect you have giardiasis.

Part 1

Part 1 of 2:

Treating Giardiasis Yourself

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1
Stay close to bathrooms. The main symptoms of giardiasis are abdominal cramps and bloating, flatulence (gas) and watery foul-smelling diarrhea that may alternate with soft, greasy stools.^{[2]
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National Health Service (UK)
Public healthcare system of the UK

Go to source} As such, you shouldn't get too far from a bathroom because you'll need one frequently throughout the day for at least 2 weeks and maybe as long as 6 weeks while your body combats the infection.
- The bloating and cramps may make it difficult to walk, so don't plan on any hikes or being too active until you're back to full health.
- Consider postponing any holidays if you get giardiasis because you'll likely be too uncomfortable to enjoy the trip.
- If you're out of your house shopping or doing errands, always carry some wet wipes in case you have to use a toilet that doesn't have any toilet paper.
2
Always wash your hands. The Giardia parasite survives outside the body within feces (poop) as spores. These hard spores can live almost anywhere for long periods of time until they get ingested via contaminated water, food or from someone's unwashed hands. The spores then hatch in your stomach or small intestine and cause infection. Washing your hands after going to the bathroom will prevent you from getting re-infected and infecting your friends and family.^{[3]
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- Be especially careful washing your hands after changing diapers or picking up pet feces.
- Always make a habit of washing your hands with soap and water before eating or preparing food.
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3
Rest as much as possible. While sick with the symptoms of giardiasis, resting is important because it'll allow your immune system more energy to fight off the infection. You'll likely be very tired due to the nausea, diarrhea and lack of appetite (which severely limits your eating), so taking some naps during the day shouldn't be difficult to do. Your immune system tends to kick it into "high gear" when you sleep.
- Some walking and light housework is fine, but take a break from the gym and other vigorous physical activities until you feel much better and stronger.
4
Keep well hydrated. Since a primary symptom of giardiasis is moderate-to-severe diarrhea, dehydration from fluid loss is always a concern. As such, replenishing your fluids throughout the day is important, so aim for at least 64 ounces of purified water (eight 8-ounce glasses). If you're very nauseous and having trouble keeping liquids down, try taking small sips of water or sucking on ice chips.^{[4]
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- In addition to water, drinking some fresh fruit / veggie juice is important to replenish your electrolytes (mineral salts), which are lost with diarrhea and vomiting. You can add a pinch of salt and half a teaspoon of honey or one teaspoon of sugar to an eight ounce glass of fruit juice. This will make your fluid replacement even easier to tolerate.
- Avoid fizzy drinks and anything with alcohol or caffeine until you're feeling healthy.
- Symptoms of dehydration include: dry mouth, thirst, tiredness, headache, dizziness, reduced urination and increased heartbeat.^{[5]
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  MedlinePlus
  Collection of medical information sourced from the US National Library of Medicine
  
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- Children with diarrhea are more susceptible to dehydration than adults are.
- Hydration is a really important part of managing mild diarrhea. If you can't intake all the hydration you need orally, you may need an IV to help replenish your fluids. If you think that you may need an IV, talk to your doctor as soon as possible.
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Eat small bland meals. You need energy to fight off the parasitic infection and to be able to go about your day, but the nausea and abdominal cramps from giardiasis can greatly diminish your appetite. As such, ease back into eating with small meals (or snacks) spaced throughout the day. Eat bland, low-fat and easy to digest foods, such as crackers, toast, soup broth, bananas and rice.^{[6]
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Research source} Don't eat during waves of nausea.
- Until you're feeling better, avoid fried foods, fatty and overly spicy foods. Avoid dairy products because you may have some degree of lactose intolerance that aggravates intestinal symptoms caused by giardiasis.
- Don't eat too much fresh fruit or veggies (especially cauliflower, onions and cabbage), because it can lead to even more gas, bloating and abdominal cramping.
- Snack on foods that can help your body get rid of parasites, such as pumpkin seeds, pomegranates, papaya, beets and carrots.
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Try taking herbs that may kill parasites. Certain compounds in some herbs have anti-parasitic properties, which means they can inhibit the spread of parasites in your body or kill them. While there are a number of herbs that are said to have anti-parasitic properties, there is not yet enough scientific evidence to support these claims. Examples include barberry, goldenseal, Oregon grape, anise seed, wormwood, curled mint and black walnuts. These anti-parasitic herbs are usually taken as tinctures under the tongue or diluted in some water. Taking them in capsules or using them to make herbal teas can work too.
- Other herbs sometimes used to kill parasites include grapefruit seed extract, fresh cloves, olive leaf extract and garlic.
- Some herbs used to treat intestinal parasites can interfere with certain medications, so use them only under the supervision of a qualified practitioner.
- Never take an herb to treat giardiasis instead of a prescribed treatment. Talk to your doctor about any herbs you intend to take.
- Be aware that barberry may decrease the effectiveness of antibiotics and grapefruit seed extract can interact poorly with many medications.

Part 2

Part 2 of 2:

Getting Medical Treatment for Giardiasis

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1
Confirm a diagnosis. If the above-mentioned symptoms linger for more than a few weeks or get worse, then call your doctor or head to a walk-in clinic. While in a clinic or hospital, your doctor can confirm a diagnosis of giardiasis by taking a stool sample and looking under a microscope for parasitic spores.^{[7]
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Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services

Go to source} A stool antigen test and trichrome staining techniques are also available to diagnose Giardia.
- As a rule, it takes 3 different stool samples to diagnose 90% of Giardia cases. Lab technicians look for a high concentration of either spores or trophozoites.
- Staining might not be sufficient to identify Giardia because variable concentration levels can make people sick — some people are more sensitive to the parasite than others.
2
Get treated for dehydration. If your diarrhea is severe and you're unable to replenish your fluids at home, you may need to get treated at a clinic or hospital for dehydration. As such, if dehydration symptoms appear (see above), call your doctor and ask for advice on where to go. The best way to replace water and electrolytes (such as sodium, potassium and calcium) is intravenously, which requires a needle to be inserted into a vein in your arm.^{[8]
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- While you're on intravenous, you can also be given glucose and various essential vitamins, which can give you more energy and reduce your mental fog.
- An intravenous session typically lasts a few hours, although you may need to stay overnight(s) if your dehydration and/or malnourishment is severe.
- You may be given some oral rehydration solution to take home — they typically contain electrolytes and glucose dissolved in water.
3
Ask your doctor about antibiotics. Some antibiotics are effective for also killing parasites, so ask your doctor about getting prescribed one if your giardiasis lasts for much more than 2 weeks. Commonly prescribed antibiotics for giardiasis include metronidazole, tinidazole and nitazoxanide.^{[9]
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Cleveland Clinic
Educational website from one of the world's leading hospitals

Go to source} Furazolidone and quinacrine are also effective for treating giardiasis, but no longer available in the U.S.
- The most common antibiotic used to combat giardiasis is metronidazole (Flagyl) — it has an efficacy rate of between 75-100%, but it often causes nausea and a metallic taste as side effects.^{[10]
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  MedlinePlus
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- Tinidazole (Tindamax) may work even better than metronidazole for giardiasis and it can be given in a single dose, but it also causes some side effects.
- Nitazoxanide (Alinia) comes as a liquid and may be easier for children to swallow and tolerate.
- Paromomycin and albendazole are less effective medications for giardiasis, but still sometimes used.
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Use anti-diarrheal medication cautiously. If your diarrhea persists for more than a few weeks, it's tempting to put a stop to it with medication, but your doctor may advise against it. Sometimes anti-diarrheal medicines can prolong the infection and make your condition worse because your body is prevented from getting rid of the parasite that's causing the diarrhea.^{[11]
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Research source} Talk to your doctor about the pros and cons.
- Over-the-counter anti-diarrheal medicines include loperamide (Imodium) and bismuth subsalicylate (Kaopectate, Pepto-Bismol). Bismuth subsalicylate can also be used to treat nausea and vomiting.
- A stronger prescription anti-diarrheal is called Lomotil, although it must be taken as soon as you start experiencing diarrhea.

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Always purify water from wells, lakes, rivers and springs. Either filter it or boil it for at least 10 minutes at 158 F or higher.^{[12]
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If your water comes from a well, have it tested. Testing of well water should be done frequently if the well is located in an area where animals graze and poop.

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After your diarrhea resolves itself, avoid dairy for 7-10 days; you might experience mild lactose intolerance. You should eat foods that are easy to digest, such as bananas, rice, baked potatoes, and applesauce. You should also stay well hydrated.

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