Why Do I Get Diarrhea

What is diarrhea

Diarrhea is passing looser stools often more frequently than normal. It is usually the result of less water being absorbed or more water being secreted by the bowel. Diarrhea is not a disease and is instead a symptom of an underlying condition. 

There are two main forms of diarrhea that are categorized by their duration. 

Acute diarrhea is the sudden appearance of at least three loose or watery stools, lasting for less than two weeks. 

If diarrhea lasts longer than this, it is considered chronic or persistent. 

Acute diarrhea is usually caused by an infection, whereas chronic is more likely to be caused by anything but an infection, requiring a different course of treatment.1

Other ways of classifying diarrhea would be

  • Secretory diarrhea- this means that more water is being secreted by the bowel, or less water is being absorbed. This is most often caused by infections
  • Osmotic diarrhea- this occurs when too much water is drawn into the bowels. It is usually caused by disorders of digestion, where food that is improperly broken down can draw water into the bowels, leading to diarrhea 
  • Inflammatory diarrhea, is where there is damage to the small intestine, meaning that there is a disturbance in the way fluid is absorbed by the body
  • Exudative diarrhea- this is the presence of blood or pus in your stool and is usually linked to infection or inflammatory bowel disease1

Causes of diarrhea

Acute diarrhea is most often caused by infections, traveler’s diarrhea, and as a side effect of medication. There are three main types of infections that can cause acute diarrhea:

  • Viral infections- such as norovirus, rotavirus, and viral gastroenteritis. These are typically more common in the wintertime
  • Bacterial infections- E.Coli, Salmonella, and Shigella, are common offenders
  • Parasitic Infections- More common in tropical climates

Traveler’s diarrhea is caused by eating contaminated food or drinking water and can be viral, bacterial, or parasitic. It is one of the most common health issues experienced when traveling2

Chronic diarrhea is usually caused by long-term health conditions. 

  • Inflammatory bowel syndrome- a condition defined by abnormal bowel habits, such as diarrhea and constipation
  • Inflammatory bowel disease- a more serious autoimmune disease, examples of which include ulcerative colitis and Crohn’sn disease
  • Medications- There are over 700 drugs associated with diarrhea, from drugs used for cancer therapy to antibiotics 
  • Celiac disease- or gluten intolerance 
  • Chronic pancreatitis- is a long-term inflammation of the pancreas, most often caused by diabetes or alcohol abuse
  • Lactose Intolerance- a condition where the enzyme used to digest lactose, found in dairy, is not present
  • Abdominal surgery- if you’ve had surgery on any of your organs in your abdomen, this can trigger chronic diarrhea 
  • Chronic infections- certain long-term infections, especially in those who have traveled to endemic regions or are immunosuppressed3

Signs and symptoms of diarrhea

Common symptoms of diarrhoea are

  • Urgent need to go to the bathroom 
  • Cramping 
  • Loss of appetite
  • Inability to control bowel movements 
  • Nausea 
  • Abdominal pain 

If an infection is present, other symptoms may be present, such as: 

  • Bloody stools 
  • Fever and chills
  • Vomiting 
  • Light-headedness, dizziness2,4 

Management and treatment for diarrhea

Most cases of diarrhea clear up after a few days without treatment or the need to see a healthcare provider. In adults, diarrhea usually improves within a few days and may take a little longer for children. During this time, there are several things you can do to help improve your symptoms 

  • Drink plenty of fluids- diarrhea can lead to dehydration, so it is important to replace the fluids that have been lost by the body
  • Oral rehydration solutions- these may be suggested by a healthcare provider to help prevent dehydration, These solutions come in sachets and can be available from pharmacists over-the-counter. They contain water and other important minerals to help with dehydration
  • Painkillers- such as paracetamol or ibuprofen, will help relieve your abdominal pain and headache

Medication may be suggested to help reduce the duration of how long your diarrhea lasts. Loperamide (AKA Imodium) is the main antidiarrhoeal drug. It works by slowing the muscle movements of your gut, allowing more water to be absorbed from the stools to make them firmer, and passed less frequently. Immodium is available without prescription over the counter, however, you should always consult a healthcare provider to make sure you are suitable to take these medications, especially if you have pre-existing medical conditions. It is also advised that you do not take Immodium if you have bloody stools or a high fever that require more urgent medical attention. 

Antibiotics are not recommended to treat most cases of diarrhea, as they can worsen the symptoms of diarrhoea, especially if caused by a viral infection. They are only recommended in severe cases, and when a specific type of bacteria that is causing your diarrhea has been identified. 

In severe cases, treatment in a hospital may be required. This is only for those who are more vulnerable, such as children, and in cases of severe dehydration. Treatment in a hospital involves receiving fluid and nutrients directly into the body intravenously. 

If caused by a specific illness, then managing this underlying condition can help manage the symptoms. For example, in coeliac disease, avoiding food containing gluten will stop the symptoms of diarrhea. If caused by inflammatory bowel disease, there are certain medications used to suppress the immune system which can help relieve symptoms.4


Is diarrhea fatal

For most, diarrhea is an uncomfortable experience and more of an inconvenience than anything else. However, this is not always the case, as it is reported that 1 in 9 deaths in children is due to diarrhea, making this the second leading cause of death for children under 5. This is because the consistent loss of body fluid through loose, watery stools can lead to severe dehydration. Diarrhea is especially detrimental in communities where safe drinking water and sanitation are not available.5

Severe diarrhea can also lead to poor kidney function, a weakened immune system, and an imbalance of important minerals and ions in the body called electrolytes. All of this can contribute to putting immense strain on your body and potentially have fatal consequences. 

How common is diarrhea

Diarrhoea is a very common symptom, and can happen to most people a few times a year. Worldwide, it is estimated that there are 1.7-5 billion cases of diarrhea annually. It is more common in developing countries, where children on average may experience diarrhea three times per year.6

How is diarrhea diagnosed

Typically, most cases of acute diarrhea sort themselves out, and do not require visiting a healthcare provider for a formal diagnosis. If there are worrying signs, such as blood in the stool, then bacterial causes must be ruled out. A stool sample may be sent off to the lab to test for specific pathogens to tailor medical treatment to. Imaging is not routine for acute diarrhea, however, if there are worrying signs of abdominal involvement, an abdominal CT may be required. 

For chronic diarrhea, the healthcare provider will need a thorough patient history to determine the origin of the diarrhea. Basic blood tests and a stool sample can help the doctor diagnose chronic diarrhea.1

Can diarrhea be prevented

Since diarrhea is often caused by an infection, practicing good hygiene can help reduce your chance of infection. 

  • Hand washing- with soap and water before eating or prepping food, and after going to the bathroom
  • Cleaning the toilet, including the seat and handle with disinfectant after a bout of diarrhea
  • Avoid sharing household items with an infected person, such as cutlery and linen
  • Wash dirty clothing and linen separately from other clothes and at a high temperature 
  • If you have diarrhea, avoid returning to work or school for at least 48 hours after you’ve had your last loose stool
  • When traveling, practice good food and water hygiene. Things to remember include not drinking tap water, avoiding undercooked food, and not brushing your teeth with tap water4

When should I call my doctor

Even though most cases of diarrhoea are mild and go away without treatment, it is important to seek help if you are concerned or have developed worrying symptoms. If your diarrhea is frequent, severe, or associated with symptoms, such as: 

  • Bloody stool 
  • Persistent vomiting 
  • Severe abdominal pain 
  • Weight loss 
  • A dark, black stool- this could be a sign of bleeding somewhere in your digestive system 
  • Dehydration- if you feel drowsy, dizzy, and not urinating frequently, can all be signs of dehydration4


Diarrhoea is an unpleasant and common experience. Fortunately, it is short-lived and does not require any treatment or hospital visits in most cases. However, it is also important to bare in mind that diarrhea can lead to more serious health consequences in the right circumstances. If your diarrhea is not improving, or you have noticed some other concerning signs, then do get in touch with your healthcare provider for advice. It is also important to keep yourself isolated and stay away from work for at least 48 hours after passing your last loose stool, to avoid passing your diarrhea on to someone else. 

This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

Get our health newsletter

Get daily health and wellness advice from our medical team.
Your privacy is important to us. Any information you provide to this website may be placed by us on our servers. If you do not agree do not provide the information.

Lauren Young

Doctor of Medicine - MD, Medical University of Sofia, Bulgaria

Lauren is a newly qualified doctor, who recently returned to the UK to pursue a career as a GP. Her passions lie in public health, medical education and health advocacy. An avid reader, Lauren has found great joy in combining her love of medicine and the written word in writing health articles for Klarity.

Leave a Reply

Your email address will not be published. Required fields are marked *

my.klarity.health presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818