Diarrhoea is an extremely common digestive symptom that almost everyone experiences at some point in their lives. Although it is usually harmless and resolves on its own within a short time, in certain cases it can be a sign of a more serious illness or lead to severe complications, such as dehydration. It is therefore important to be aware of the causes of diarrhoea, how to recognise it, and when to seek medical help.
This article provides a comprehensive guide to the most important things to know about diarrhoea. We’ll help you understand exactly what diarrhoea is, what types there are, and what might be causing it. We’ll explain the possible treatment options in detail, ranging from home remedies and medication to a suitable diet. Our aim is to help you alleviate your symptoms and recover as quickly as possible by providing reliable and easy-to-understand information.
What exactly is diarrhoea?
Diarrhoea (Latin: diarrhoea) can be clinically defined as three or more loose, watery bowel movements per day, or an increase in the frequency of bowel movements compared with the individual’s usual pattern. The consistency of the stool corresponds to type 6 (mushy) or 7 (watery) on the Bristol Stool Scale. Diarrhoea is often accompanied by other symptoms, such as an urgent need to pass stools, abdominal pain, bloating or incontinence (the inability to control bowel movements).
Types of diarrhoea
Diarrhoea can be classified into several groups according to its duration and underlying cause. Based on duration, we distinguish between:
- Acute diarrhoea: This is the most common form, which usually lasts for less than 14 days. It is most often caused by infections (viral or bacterial), food poisoning or side effects of medication.
- Persistent (persistent) diarrhoea: It refers to diarrhoea lasting between 14 and 30 days.
- Chronic diarrhoea: Chronic diarrhoea is defined as symptoms lasting for more than 30 days. There are often more complex underlying causes, such as inflammatory bowel diseases, malabsorption disorders or functional bowel disorders, such as irritable bowel syndrome (IBS). Chronic diarrhoea always requires a thorough gastroenterological investigation.
We can also classify diarrhoea according to the nature of the stools:
- Aqueous (secretory or osmotic): It is characterised by large volumes of watery stools. Secretory diarrhoea is caused by increased fluid secretion by the intestinal mucosa (e.g. cholera), whilst osmotic diarrhoea is caused by substances remaining in the intestine that are not absorbed (e.g. lactose in the case of lactose intolerance), which draw water into the intestine.
- Bloody and mucous (dysenteriform): Blood and mucus appear in the stools, indicating inflammation or damage to the intestinal mucosa. This is often caused by bacterial infections (e.g. Shigella, Campylobacter) or inflammatory bowel diseases.
- Steatorrhoea: It is characterised by pale, greasy, voluminous and foul-smelling stools, which indicate a fat malabsorption disorder (e.g. coeliac disease, pancreatic insufficiency).
The most common causes of diarrhoea
There are numerous factors that can underlie diarrhoea, ranging from common infections to serious, chronic conditions.
Infections
Infections are the most common causes of acute diarrhoea.
- Viruses: Rotaviruses, noroviruses, adenoviruses and astroviruses are particularly common. These cause illnesses commonly referred to as „stomach flu” or „intestinal infection”, which are usually short-lived and are accompanied by vomiting, abdominal pain and, occasionally, fever. They are spread via the faecal-oral route, through contaminated food, water or objects.
- Bacteria: They can cause food poisoning (e.g. toxins produced by Staphylococcus aureus, Bacillus cereus and Clostridium perfringens) or direct intestinal infection (e.g. Salmonella, Campylobacter, Shigella, Yersinia, certain strains of E. coli). They typically enter the body through the consumption of contaminated food that has not been properly heat-treated (e.g. eggs, poultry) or water.
- Parasites: Less commonly, parasitic infections (e.g. Giardia lamblia, Cryptosporidium, Entamoeba histolytica) can also cause diarrhoea, particularly during travel to exotic destinations or in patients with a weakened immune system.
Medicines and toxins
Diarrhoea can occur as a side effect of many medicines.
- Antibiotics: Courses of antibiotics often disrupt the natural balance of the gut flora, which can lead to diarrhoea. In severe cases, they can cause an overgrowth of the Clostridioides difficile bacterium, which can lead to severe, even life-threatening, inflammation of the bowel (colitis).
- Other medicines: Proton pump inhibitors (PPIs), non-steroidal anti-inflammatory drugs (NSAIDs), certain antidepressants (SSRIs), chemotherapy drugs (cytostatics), or even metformin (used to treat diabetes) can cause diarrhoea.
Food intolerances and allergies
- Lactose intolerance: It is caused by a lack of, or reduced activity of, the lactase enzyme required to digest milk sugar (lactose). The unabsorbed lactose begins to ferment in the large intestine, resulting in bloating, abdominal cramps and osmotic diarrhoea.
- Coeliac disease (gluten sensitivity): An autoimmune disease in which the consumption of gluten (a protein found in wheat, barley and rye) leads to damage to the lining of the small intestine and malabsorption. Typical symptoms include chronic, fatty diarrhoea, weight loss and nutritional deficiencies.
- Non-coeliac gluten sensitivity (NCGS): Abdominal symptoms (pain, bloating, diarrhoea) and extraintestinal symptoms (e.g. headache, fatigue), but does not involve damage to the intestinal lining.
- Food allergies: An immune reaction triggered by certain foods (e.g. milk, eggs, fish) can also cause diarrhoea, usually shortly after eating.
Chronic illnesses
Chronic conditions are often the underlying cause of persistent diarrhoea.
- Irritable bowel syndrome (IBS): A functional bowel disorder, in the diarrhoea-predominant form of which (IBS-D) abdominal pain is accompanied by frequent, loose stools, particularly after meals or in stressful situations.
- Inflammatory bowel diseases (IBD): Crohn’s disease and ulcerative colitis are chronic inflammatory bowel diseases of autoimmune origin. Their main symptoms are bloody, mucous diarrhoea, abdominal pain and weight loss.
- Microscopic colitis: This is a form of chronic watery diarrhoea in which the endoscopic appearance of the large bowel is normal, but a histological examination reveals inflammation. It is more common in older people, particularly in women.
- Absorption disorders (malabsorption): A number of conditions (e.g. coeliac disease, SIBO, short bowel syndrome, pancreatic insufficiency) can lead to inadequate absorption of nutrients, resulting in chronic diarrhoea and nutritional deficiencies.
- Diverticulosis and diverticulitis: Inflammation (diverticulitis) of the small pouches (diverticula) that form in the wall of the large intestine can also cause diarrhoea.
When should we see a doctor?
Although most cases of acute diarrhoea can be treated at home, if certain warning signs are present, a medical examination – or indeed a specialist gastroenterological examination – is definitely recommended:
- High fever of over 38.5°C.
- Severe, cramp-like abdominal pain or abdominal tightness.
- Bloody or black (tar-like) stools.
- Signs of dehydration: reduced urine output, dark-coloured urine, dry mouth, sunken eyes, dizziness, weakness.
- If the diarrhoea lasts for more than 48 hours and does not improve.
- More than 6 bowel movements a day.
- In the case of elderly patients (aged 70 or over) or those with a compromised immune system.
- Significant, unintentional weight loss.
- Diarrhoea at night that wakes you from sleep.
Chronic diarrhoea that has persisted for weeks always requires a thorough investigation to identify the underlying cause. In such cases, it is advisable to consult a Endomedix Gastroenterology Centre consult their specialists, who will assist in establishing an accurate diagnosis using a full range of diagnostic tests (laboratory tests, stool tests, endoscopy).
Treating diarrhoea
The primary aim of treatment is to relieve symptoms, restore fluid and electrolyte balance, and address the underlying cause.
Home treatment and dietary advice
Acute, non-severe diarrhoea can usually be treated effectively at home.
- Fluid replacement (rehydration): This is the most important thing you can do to prevent dehydration. Drink plenty of fluids, such as water, weak tea or chicken stock. Special rehydration solutions (ORS) containing salts and sugar are available from pharmacies and are the most effective way of replacing lost fluids and electrolytes.
- Diet: Instead of the old „salty water, salty crisps” principle, a gradual return to a normal diet is now recommended. To begin with, eat easily digestible foods that are low in fibre and fat. These include boiled potatoes, boiled rice, toast, bananas, steamed apples or carrots. Avoid fatty, spicy and sugary foods, as well as milk and dairy products, caffeine and alcohol, as these can make your symptoms worse.
- Probiotics: Although the evidence is not always clear-cut, certain probiotic strains (e.g. Lactobacillus, Saccharomyces boulardii) may help to restore the balance of the gut flora, particularly in cases of antibiotic-associated diarrhoea.
Medication
The use of medicines always depends on the underlying cause and the severity of the symptoms.
- Antidiarrhoeal agents (e.g. loperamide): They reduce bowel movements and the frequency of bowel movements. It is important to note that their use is not recommended in cases of infectious diarrhoea, particularly bloody or mucoid diarrhoea, as they may worsen the condition by preventing the elimination of pathogens. They are mainly suitable for functional diarrhoea (e.g. IBS-D) or non-infectious watery diarrhoea, but only on medical advice.
- Sorbents and coating agents (e.g. activated charcoal, bismuth subsalicylate): They bind to toxins in the gut, but their effectiveness is limited.
- Antibiotics: These should only be used on medical prescription in cases of confirmed bacterial infection (e.g. Shigella, C. difficile). Unnecessary use is harmful.
- Specific medicines for chronic conditions: Treating the underlying condition is the most important thing. In cases of IBS, IBD or other chronic conditions, a gastroenterologist will prescribe the appropriate treatment (e.g. antispasmodics, anti-inflammatory drugs, biologic therapy).
How can the Endomedix Gastroenterology Centre help?
If your diarrhoea persists, or if you experience any of the warning signs mentioned above, do not delay seeing a specialist. The Endomedix Gastroenterology Centre welcomes patients in a modern, friendly environment, with a team of experienced specialists.
The centre offers a wide range of diagnostic options for investigating the causes of diarrhoea:
- Specialist consultation: Taking a detailed medical history and carrying out a physical examination are the first steps towards a diagnosis.
- Laboratory and stool tests: They help to detect inflammation, anaemia, infections, malabsorption or hidden bleeding.
- Exhalation tests: They are suitable for diagnosing lactose intolerance, fructose malabsorption or small intestinal bacterial overgrowth (SIBO).
- Endoscopic examinations (colonoscopy): It is a key tool in the investigation of chronic diarrhoea. A colonoscopy allows for direct examination of the intestinal mucosa, the taking of tissue samples (biopsies), and the diagnosis of conditions such as inflammatory bowel disease, microscopic colitis or tumours. The At the Endomedix Gastroenterology Centre The examinations are carried out using state-of-the-art technology, with the least possible discomfort to the patient, and may even be performed under general anaesthesia.
Summary
Diarrhoea is an unpleasant but generally harmless symptom which, with appropriate home treatment – primarily plenty of fluids and a gentle diet – will clear up within a few days. However, it is important to recognise the warning signs that may indicate a more serious problem. Identifying the cause of persistent diarrhoea – which has lasted for weeks or is accompanied by severe symptoms – is essential for ensuring appropriate treatment and preventing complications.
Don’t underestimate persistent diarrhoea! If your symptoms do not improve, or if you notice any worrying signs, please do not hesitate to contact the Endomedix Gastroenterology Centre our experts, who will help you identify the root cause of the problem and find the most effective solution for you.
