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Diarrhea and Dehydration

Diarrhea and Dehydration

Does Diarrhea Dehydrate Me?


Diarrhea is a health concern, but what does it have to do with hydration? Can dehydration lead to diarrhea?

Scientifically-speaking, diarrhea is an increased frequency and fluidity in our poop. But we really know it as an unfortunate inconvenience that restricts our ability to go about our day. To say the least, it’s uncomfortable, unpredictable, and of an urgent nature. Most significantly, diarrhea causes you to lose a lot of fluid.

Every time you lose fluid and don’t replenish it, you’re one step closer to dehydration. Diarrhea is no exception—it can have an effect on hydration status and healthy electrolyte levels. Electrolytes are charged particles (such as potassium and sodium ions) that ensure the smooth running of our bodies by maintaining healthy levels of fluid inside and outside our cells [1].

Electrolytes and water levels within the body go hand-in-hand. If we lose water from the body we also lose electrolytes. So, when you have diarrhea, you lose electrolytes and water. But before we look at the effects of diarrhea let’s look at why we get diarrhea in the first place.

Why do we get diarrhea?

wet table

Diarrhea is a disruption in the normal movement of water and electrolytes in the gut. Electrolytes move via small channels or by tiny protein pumps in the gut cells. Water then moves by osmosis from areas of low electrolyte concentration to areas of high electrolyte concentration [2]. Think of it like how a paper towel draws up water from the table. In just the same way, the electrolytes (which are all ions) move water inside the body or can expel it into the gut as happens in diarrhea. When this functions properly, as fluid enters the small intestine, 90% is absorbed helping to hydrate us properly [3]  

Causes of diarrhea can be split into a number of categories. Firstly, it may be a sign of bacterial infection in the gut. The bacteria Escherichia coli, for example, causes disease in 75,000 people in the US every year [4]. This bacteria produces two toxins, one of which opens an electrolyte channel in the cells of the gut. This leads to the loss of ions from the body. The other bacteria-produced toxin causes the insertion of a channel into the gut membrane cells, through which more ions are lost from the body [5]. The movement of ions into the gut then draws out water from the body, causing large volumes of liquid to be lost during diarrhea.  

Viral infections may similarly upset the balance of ions and water in the gut, causing diarrhea [6]. Such infections may be rotavirus, similar to the bugs that give you a sore throat during the cold season. Additionally, diarrhea can be caused by a medical condition of the gut such as Crohn’s disease, Coeliac disease, food intolerance, or irritable bowel syndrome [7].  

The consequences of diarrhea on the body

IV dextrose

Diarrhea can cause electrolyte imbalances and dehydration. In a study of 57 children admitted to a pediatric ward with diarrhea and dehydration, researchers found that 56% of the children had low sodium levels and 46% had low potassium levels [8]. This may lead to one feeling tired as well as a drop in physical and mental performance.

Dehydration caused by diarrhea can first be associated with thirst and a dry mouth. As it worsens over time, it may lead to feelings of restless and irritability, as well as headaches, dizziness, dry skin, and weakness [9].

Stop dehydration before it happens by adding a pack of Hydrant to your next glass of water.


Writer: James Gunnell
Editor: Elizabeth Trelstad, www.hellobeaker.com


1. “Electrolytes.” Melissa Stoppler and William Shiel. MedicineNet. https://www.medicinenet.com/electrolytes/article.htm#what_are_electrolytes - This article describes the role of electrolytes in the body very simply.
2. “Absorption of Water and Electrolytes.” VIVO pathophysiology. http://www.vivo.colostate.edu/hbooks/pathphys/digestion/smallgut/absorb_water.html - This article describes the process of absorption of water and ions in the gut.
3. “Pathophysiology of watery diarrhoea: Dehydration and Rehydration”. World Health Organization. 1992. http://rehydrate.org/diarrhoea/tmsdd/2med.htm - A textbook describing the movement of ions in the gut and how this goes wrong in diarrhoea.
4. “Escherichia coli 0157: H7 Diarrhea in the United States: Clinical and Epidemiologic Features”. Elizabeth Astagneau et al. 2004. Annals of Internal Medicine. An epidemiological study on the prevalence of E. coli infection in the U.S by stool sampling of patients in 10 hospitals.
5. “Infectious diarrhea: Cellular and molecular mechanisms”. By Kim Hodges and Ravinder Gill. 2010. Gut Microbes. This is a scientific review of the way infections cause diarrhea, using in-depth scientific explanations involving explanations of different transporters and channels within the gut.
6. “2.Acute infectious diarrhoea and dehydration in children” by Elizabeth Elliott and Jacqueline Dalby-Payne. MJA Practice essentials - Paediatrics. An academic journal article describing the causes of diarrhea and gastroenteritis in children.
7. “Diarrhoea: Why it happens and how to treat it.” in WebMD. https://www.webmd.com/digestive-disorders/digestive-diseases-diarrhea#1 - A simply written article listing the causes of diarrhoea and describing disease of the gut.
8. “Acid base and electrolyte disturbance in diarrhoea” Shah GS et al., 2007. In Kathmadu University Medical Journal. A retrospective review of patients (children) suffering from diarrhea and an analysis of electrolyte levels in a paediatric hospital.
9. ‘Why is Dehydration so dangerous?” The Rehydration project. http://rehydrate.org/dehydration/ - An easily accessible website describing the signs, symptoms, causes, and consequences of dehydration from diarrhea.