What are the Symptoms of Giardiasis?

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  • Originally Written By: Meghan Cunningham
  • Revised By: C. Mitchell
  • Edited By: C. Wilborn
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  • Last Modified Date: 04 January 2020
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The most common symptoms of giardiasis are nausea, vomiting, and diarrhea, along with flatulence, bloating, and belching. More severe symptoms include fatigue, abdominal distension and cramping, and persistent headaches. It’s easy for people to confuse these symptoms with those of an ordinary stomach virus, particularly at first, but in most cases they’re much more severe and long-lasting, and often also require medical attention in order to dissipate. Giardiasis is typically caused by a parasite, and the infection doesn’t always go away on its own the way most stomach bugs will.

Gastrointestinal Problems

Symptoms of giardiasis are largely gastrointestinal, which means that they are typically centered in a person’s digestive tract. The infection often impacts the intestines’ ability to take nutrients out of food and waste products, which can lead to loose, watery stools, or stools with a greasy consistency. Explosive, burning diarrhea is also common, but somewhat confusingly constipation may be a problem, too. Victims often alternate between intense bouts of diarrhea and periods in which they are unable to move their bowels. Most of the time this is owing to the parasite’s disruption of normal intestinal and colon function.


Gas accumulation is also common. A small amount of gas is common in the digestive tract as a byproduct of nutrient and waste breakdown, but people who are infected with giardiasis often have more gas then normal. This can lead to painful bloating and foul-smelling flatulence. A victim may also belch or burp repeatedly, which often causes bad breath. Depending on the severity of the infection, these symptoms may last anywhere from two to ten days.

Stomach Pain

In severe cases people may also experience intense stomach cramps and tenderness, often on account of disrupted acid levels in the digestive tract. Vomiting, either due to stomach upset or pain, is common, too, as are feelings of severe indigestion and heartburn. In some instances the person may feel worse after he or she eats, and may also feel nauseated, lack an appetite, and feel unwell in general.

In Extreme Cases

These sorts of infections usually happen along a spectrum with some cases being relatively minor and others extreme. In the worst cases, people often experience a fever and fluid imbalance in the body that can lead to chronic headaches. When the infection is really bad the intestines can essentially shut down, or cease functioning; this often prohibits the absorption of nutrients from food, which can lead to weight loss, muscular degeneration, and dehydration.

Treatment Options

Giardiasis usually requires medical attention, both in terms of diagnosis and treatment. Sometimes symptoms will go away on their own, but this is normally only the case when the initial infection has been minor. It’s hard to know this from the outset. Most of the time, symptoms that start out relatively mild get progressively worse until a person gets treated. Even people who seem to have recovered may still be carriers of the parasite, which means that they can transmit it to others.

Drug intervention is often the best course of action, particularly in serious cases. No drug works for all giardiasis cases, though, which makes relapse something of a frequent problem. Medical providers often start by prescribing an antiparasitic, which is any of a series of drugs designed to kill parasites. This is often given to the patient as well as anyone who may be in close contact with him or her. Rehydration tablets, intravenous salt solutions, and other stabilizing medications are sometimes also given.

Antidiarrheal medicines, however, should generally not be used because they can prolong the infection by creating a more “stable” intestinal environment where the parasite can grow and reproduce. The same is true for most ordinary cold and flu medications. People who suspect that they have become infected with giardiasis are usually advised to get a professional opinion and diagnosis before self-treating.

Prevention and Safety Tips

The best way to avoid infection is to keep the parasite that causes giardiasis, Giardia lamblia, out of the body, but this isn’t always as easy as it sounds. It is found in most parts of the world, in rural, urban, and wilderness areas alike. In most cases it is transmitted through feces; touching fecal matter and then touching the mouth or preparing food is one of the fastest ways it spreads. It can also be present in drinking water, though. Proper hygiene, rigorous cooking, and filtering or boiling water are some of the easiest ways for people to stay protected, particularly in regions where parasitic infections are more prevalent.


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Discuss this Article

Post 5

The thing that isn't mentioned is that the parasite can stay dormant in the body for decades. It can also cause IBS, Lactose intolerance, ME and G.E.R.D.

Post 4

I have bad explosive gas, headache and body aches, I get real hot and cold. I wonder if this is giardiasis?

Post 3

I am one of the rare people who experience constipation and not diarrhea from giardiasis. More so than the constipation, I hate the fatigue. I feel so tired all the time. I almost feel like I have the flu, I just want to stay in bed.

I am glad that I am not vomiting or losing weight though. I think things would be so much worse if I had those symptoms as well. I just hate this infection and I'm scared that it's going to return after treatment. I've heard that it returns for many people even after antibiotics.

Post 2

@ZipLine-- Yea, sounds about right.

I got a giardia infection when I was traveling abroad. I must have drank dirty water there. I was so sick for two weeks, running to the bathroom constantly! I was dehydrated because of the diarrhea and had to get an IV at the hospital.

Post 1

I was treated for giardiasis last month. I basically had all of the giardiasis symptoms mentioned in the article. Diarrhea, nausea and upset stomach, flatulence, cramps and headaches. I was diagnosed after a stool test and took antibiotics.

I had another test done after that and the infection is gone. But I'm still suffering from a couple of the symptoms-- upset stomach and cramps.

I don't know if my body is still trying to recuperate from the infection or what. Has anyone else had giardiasis? Did you have a similar experience?

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