What Are the Causes of Diarrhoea?

Do you spend more time sitting on the toilet than on the couch? Diarrhoea is a symptom that could be diminishing your quality of life, especially if you’ve had it for a long time. You may wonder what could be causing it.

If you suffer from chronic diarrhoea, it could be linked to a gastrointestinal problem. If it appeared recently, on the other hand, it is more likely to be a viral, bacterial or from a parasite infection. To find out what might be causing your diarrhoea and how to deal with it, keep reading our article!

Key Facts

  • It is considered diarrhoea when the bowel rhythm is unusually high, with three or more liquid or pasty stools a day.  
  • Diarrhoea is most often caused by intestinal infections with viruses or bacteria. It typically clears up on its own, and staying well hydrated is the best thing to do. 
  • Treatment of diarrhoea with medications such as antibiotics and antiparasitic drugs should be left to your doctor’s discretion, as these could make your symptoms worse if you don’t use them properly!

The Causes of Diarrhoea: What You Need to Know

Understanding what has caused diarrhoea is essential to start managing it in the best possible way (1):

Causes of diarrhoeaSymptoms and accompanying signsTreatment
VirusAcute diarrhoea
Abdominal pain
Nausea
Vomiting
Dehydration 
General measures (hydration, replenishment of electrolytes)
BacteriasAcute diarrhoea
Fever
Abdominal pain
Nausea
Vomiting
Stools with blood and mucus
General measures
Antibiotics ( with medical indication only)
ParasitesAcute/chronic diarrhoea
Bloody stools
Greasy stools
Abdominal pain
Weight loss 
General measures
Antiparasitic drugs (with medical indication only)
Food intolerancesAcute/chronic diarrhoea
Abdominal pain
Abdominal swelling 
Gases
Diarrhoea that starts or gets worse after certain meals
Dietary changes
Diseases Chronic diarrhoea
Various symptoms
Treating the disease that causes diarrhoea
Supplements 
Other causes:
– Traveller’s diarrhoea
– Use of antibiotics
– Diarrhoea in immunocompromised patients
Acute/chronic diarrhoea
Various symptoms
General measures
Medical treatment (if necessary)
Supplements

Viral diarrhoea

Viruses that affect the digestive system are typically contracted through contaminated food, drink and utensils. You can also become infected through very close contact with other infected people, just as you can catch a cold (2).

Viruses such as rotavirus and norovirus produce what is known as viral gastroenteritis, which some people call stomach flu. Diarrhoea is commonly accompanied by abdominal pain, nausea, vomiting, and fever in some cases (3)

There is no specific treatment for the viruses that cause diarrhoea, but they can be prevented with rotavirus vaccine (4) and proper washing of hands and food (5)

girl wih stomachache
It is considered diarrhoea when the bowel rhythm is unusually high, with three or more liquid or pasty stools a day. (Source: Piksel: 41960117/ 123rf.com)

Diarrhoea caused by bacteria

Also known as bacterial gastroenteritis, this type of diarrhoea is associated with the consumption of food and drink infected with bacteria. This type of diarrhoea doesn’t spread like a cold (6).

Several types of bacteria can cause this type of infection, such as (7):

  • E. Coli
  • Salmonella 
  • Yersinia 
  • Shigella 
  • Staphylococci
  • Campylobacter
  • Clostridium 

It is often associated with symptoms such as abdominal pain, loss of appetite, nausea, vomiting, and fever. Stools may contain mucus and/or blood.

Bacterial diarrhoea generally resolves on its own. However, you should see your physician if your diarrhoea does not improve or worsens after more than five days. 

On the other hand, very young babies should be taken to their paediatrician as soon as vomiting or diarrhoea starts.

Diarrhoea caused by parasites

Also called intestinal protozoa, parasitic diarrhoea is transmitted by the faecal-oral route. This means that particles of “poo” have somehow reached your mouth, either from poorly washed food or from eating with dirty hands.

These diarrhoeas can vary greatly from one another. For example, amebiasis causes bloody diarrhoea (8), while others like giardiasis can cause fatty diarrhoea (known as steatosis) (9)

Diarrhoea caused by parasites often lasts for a long time, mainly affecting children in developing countries (10). While some cases may resolve on their own, most need medical treatment with antiparasitic drugs such as tinidazole, metronidazole or clotrimazole (11).

getting some toilet paper
Diarrhoea is most often caused by intestinal infections with viruses or bacteria. (Source: Arnoaltix: 137403905/ 123rf.com)

Diarrhoea caused by food intolerance

Food intolerances can lead to diarrhoea and gastrointestinal discomfort if certain components of your food are incompatible with your body (12). The most common are:

Lactose intolerance

These intolerances are much easier to identify, as they often cause diarrhoea, gas, and abdominal bloating right after eating any lactose-containing food (milk, cheese, or creams) (13)

They are much more common in adolescents and adults, since children are more capable of breaking down the protein in milk as they must feed on it in order to survive.

Gluten intolerance

Unlike lactose intolerance, gluten intolerance or coeliac disease is due to an attack on the intestine by our immune system when it detects the presence of the gluten protein.

The symptoms start from childhood, since the body’s defences are designed to attack this protein, while destroying the villi that absorb nutrients (14).

This intolerance can cause diarrhoea, constipation, stunded growth, and learning problems in children.

Am I intolerant or allergic?

An intolerance and an allergy are different conditions, since the latter sees the food as an enemy and the immune system generates exaggerated inflammatory reactions to attack it.

The symptoms are widespread, producing skin redness, itching (in the throat and skin), nasal and eye congestion, and in some cases breathing difficulty, which is a life-threatening emergency!

guy with a glass of milk
Diarrhoea due to lactose intolerance is very common. (Source: Lightfieldstudios: 120969509/ 123rf.com)

Diseases that cause diarrhoea

Some diseases that affect our digestive system can lead to diarrhoea that lasts a long time, which is why it is called chronic diarrhoea. The most common are:

  • Irritable bowel syndrome: This disorder of the intestine can produce episodes of diarrhoea and chronic constipation. It has no clear origin but often appears after intestinal infections or long periods of emotional stress.
  • Crohn’s disease: This condition causes chronic inflammation of the intestine. It can affect any part of the digestive tract (from the mouth to the anus) and can cause intestinal bleeding that may lead to anaemia.

These diarrhoeas must be treated by a specialist, as the cause must be identified and addressed.

In some cases, probiotics can support your treatment by helping to repopulate your gut with good microorganisms (15, 16, 17).

Other diarrhoeas

We also want to highlight three very important causes of diarrhoea in this small section:

1. Antibiotic-induced diarrhoea

This type of diarrhoea is caused by the destruction of our intestinal microflora by the use of antibiotics. This exposes our intestines to the attack of harmful germs.

This is why it is essential to monitor the use of antibiotics, as they can be both a cause of diarrhoea and a treatment (if used correctly under the supervision of your physician) (18).

Probiotics could be an effective treatment to prevent the onset of this type of diarrhoea if you need to follow an antibiotic treatment or even speed up your recovery.

elder guy reading pills instructions
Monitoring the use of antibiotics is essential. (Source: Dolgachov: 116790587/ 123rf.com)

2. Traveller’s diarrhoea

As the name implies, this type of diarrhoea happens during travels. The cause is typically a viral, bacterial, or parasitic infection by germs from certain regions that often do not affect people who have lived there for a long time (19).

When travelling, make sure you consume food and drink from reliable sources. Don’t drink water from showers or taps and keep eating utensils clean (20)

3. Diarrhoea in immunocompromised patients

When our defences are weakened, as can happen in diseases such as HIV/AIDS and lupus or in people with organ transplants, our intestines are much more vulnerable to diarrhoea caused by viruses, bacteria, and parasites (21)

Your treating physician will determine the most effective treatment for these diarrhoeas, as they can be caused by different germs and have varying consequences.


Our Conclusions

Diarrhoea is merely a symptom that can have many causes. The most important thing to identify it is to identify its main characteristics such as the presence of fat, blood or mucus in the stool, and the accompanying symptoms such as fever, as well as their duration.

Most types of diarrhoea begin abruptly and disappear within a few days. However, you should see your physician for advice if your diarrhoea is prolonged or worsens over time.

If you found our article useful, don’t forget to share it on your social media. You can leave any questions you have in the section below, and we’ll be happy to get back to you.

(Source of featured image: Ngamnithiporn: 140813354/ 123rf.com)

References(21)

  1. Personal de MedlinePlus. Diarrea. 2020
  2. Personal de MedlinePlus. Gastroenteritis. 2020.
  3. Bányai K, Estes MK, Martella V, Parashar UD. Viral gastroenteritis. Lancet 2018;392:175–86.
  4. Troeger C, Khalil IA, Rao PC, Cao S, Blacker BF, Ahmed T, et al. Rotavirus vaccination and the Global Burden of Rotavirus diarrhea among children younger than 5 years. JAMA Pediatr 2018;172:958–65.
  5. Clark B, McKendrick M. A review of viral gastroenteritis. Curr Opin Infect Dis 2004;17:461–9.
  6. Personal de MedlinePlus. Gastroenteritis bacteriana. 2020.
  7. Humphries RM, Linscott AJ. Practical guidance for clinical microbiology laboratories: Diagnosis of bacterial gastroenteritis. Clin Microbiol Rev 2015;28:3–31.
  8. Haque R, Huston CD, Hughes M, Houpt E, Petri WA Jr. Amebiasis. N Engl J Med 2003;348:1565–73.
  9. Wolfe MS. Giardiasis. Clin Microbiol Rev 1992;5:93–100.
  10. Solano L, Acuña I, Barón MA, Morón de Salim A, Sánchez A. Influencia de las parasitosis intestinales y otros antecedentes infecciosos sobre el estado nutricional antropométrico de niños en situación de pobreza. Parasitol Latinoam 2008;63.
  11. Parásitos intestinales. PediatriaintegralEs n.d. 2020
  12. Contreras SJ. Intolerancias alimentarias y diarrea funcional. Revista andaluza de patología digestiva 2018;41:127–32.
  13. Alliende F. Intolerancia a la lactosa y otros disacáridos. Gastroenterología Latinoamericana. 2007.
  14. Balakireva AV, Zamyatnin AA. Properties of gluten intolerance: Gluten structure, evolution, pathogenicity and detoxification capabilities. Nutrients 2016;8:644.
  15. Rahimi R, Nikfar S, Rahimi F, Elahi B, Derakhshani S, Vafaie M, et al. A meta-analysis on the efficacy of probiotics for maintenance of remission and prevention of clinical and endoscopic relapse in Crohn’s disease. Dig Dis Sci. 2008;53(9):2524–31.
  16. Moayyedi P, Ford AC, Talley NJ, Cremonini F, Foxx-Orenstein AE, Brandt LJ, et al. The efficacy of probiotics in the treatment of irritable bowel syndrome: a systematic review. Gut. 2010;59(3):325–32.
  17. Katherine Zeratsky RD. Probióticos y prebióticos: lo que debes saber [Internet]. Mayo Clinic. Mayo Foundation for Medical Education and Research; 2018.
  18. David R. Antibiotic Therapy for Acute Watery Diarrhea and Dysentery. Military Medicine. 2017
  19. Vila J, Oliveira I, Zboromyrska Y, Gascon J. Diarrea del viajero. Enfermedades Infecciosas Microbiología Clínica 2016;34:579–84.
  20. Shlim DR. Looking for evidence that personal hygiene precautions prevent traveler’s diarrhea. Clin Infect Dis 2005;41 Suppl 8:S531-5.
  21. Frisancho O. Diarrea en el Inmunocomprometido. EduPe. n.d. 1997
Previous What Are Vitamin C's Health Benefits? Next What Are the Benefits of Vitamin B12?
Official website
Personal de MedlinePlus. Diarrea. 2020
Go to source
Official website
Personal de MedlinePlus. Gastroenteritis. 2020.
Go to source
Scientific Article
Bányai K, Estes MK, Martella V, Parashar UD. Viral gastroenteritis. Lancet 2018;392:175–86.
Go to source
Human Clinical Trials
Troeger C, Khalil IA, Rao PC, Cao S, Blacker BF, Ahmed T, et al. Rotavirus vaccination and the Global Burden of Rotavirus diarrhea among children younger than 5 years. JAMA Pediatr 2018;172:958–65.
Go to source
Scientific Article
Clark B, McKendrick M. A review of viral gastroenteritis. Curr Opin Infect Dis 2004;17:461–9.
Go to source
Official website
Personal de MedlinePlus. Gastroenteritis bacteriana. 2020.
Go to source
Scientific Article
Humphries RM, Linscott AJ. Practical guidance for clinical microbiology laboratories: Diagnosis of bacterial gastroenteritis. Clin Microbiol Rev 2015;28:3–31.
Go to source
Scientific Article
Haque R, Huston CD, Hughes M, Houpt E, Petri WA Jr. Amebiasis. N Engl J Med 2003;348:1565–73.
Go to source
Scientific Article
Wolfe MS. Giardiasis. Clin Microbiol Rev 1992;5:93–100.
Go to source
Human Clinical Trials
Solano L, Acuña I, Barón MA, Morón de Salim A, Sánchez A. Influencia de las parasitosis intestinales y otros antecedentes infecciosos sobre el estado nutricional antropométrico de niños en situación de pobreza. Parasitol Latinoam 2008;63.
Go to source
Official website
Parásitos intestinales. PediatriaintegralEs n.d. 2020
Go to source
Scientific Article
Contreras SJ. Intolerancias alimentarias y diarrea funcional. Revista andaluza de patología digestiva 2018;41:127–32.
Go to source
Scientific Article
Alliende F. Intolerancia a la lactosa y otros disacáridos. Gastroenterología Latinoamericana. 2007.
Go to source
Scientific Article
Balakireva AV, Zamyatnin AA. Properties of gluten intolerance: Gluten structure, evolution, pathogenicity and detoxification capabilities. Nutrients 2016;8:644.
Go to source
Scientific Article
Rahimi R, Nikfar S, Rahimi F, Elahi B, Derakhshani S, Vafaie M, et al. A meta-analysis on the efficacy of probiotics for maintenance of remission and prevention of clinical and endoscopic relapse in Crohn’s disease. Dig Dis Sci. 2008;53(9):2524–31.
Go to source
Literature review
Moayyedi P, Ford AC, Talley NJ, Cremonini F, Foxx-Orenstein AE, Brandt LJ, et al. The efficacy of probiotics in the treatment of irritable bowel syndrome: a systematic review. Gut. 2010;59(3):325–32.
Go to source
Official website
Katherine Zeratsky RD. Probióticos y prebióticos: lo que debes saber [Internet]. Mayo Clinic. Mayo Foundation for Medical Education and Research; 2018.
Go to source
Scientific Article
David R. Antibiotic Therapy for Acute Watery Diarrhea and Dysentery. Military Medicine. 2017
Go to source
Scientific Article
Vila J, Oliveira I, Zboromyrska Y, Gascon J. Diarrea del viajero. Enfermedades Infecciosas Microbiología Clínica 2016;34:579–84.
Go to source
Scientific Article
Shlim DR. Looking for evidence that personal hygiene precautions prevent traveler’s diarrhea. Clin Infect Dis 2005;41 Suppl 8:S531-5.
Go to source
Scientific Article
Frisancho O. Diarrea en el Inmunocomprometido. EduPe. n.d. 1997
Go to source