What causes diarrhoea

Overview

Diarrhea, also known as diarrhoea, is a common condition characterized by loose, watery stools that occur more frequently than usual. While most cases are mild and resolve on their own within a day or two, persistent or severe diarrhea can be a sign of a more serious issue and can lead to dehydration. Understanding the various causes of diarrhea is crucial for effective prevention and management.

Common Causes of Diarrhea

Infections

Infectious agents are the most common culprits behind acute diarrhea. These can be categorized as:

• Viral Infections: Viruses are responsible for the majority of diarrhea cases worldwide. Common culprits include norovirus (often called the 'winter vomiting bug'), rotavirus (a leading cause in infants and young children), adenovirus, and astrovirus. These viruses spread easily through contaminated food, water, or person-to-person contact. Symptoms often include watery diarrhea, vomiting, fever, and abdominal cramps.
• Bacterial Infections: Bacteria can cause diarrhea when ingested through contaminated food or water. Common bacterial pathogens include Salmonella, Campylobacter, Shigella, and Escherichia coli (E. coli). Food poisoning is a frequent cause of bacterial diarrhea, often associated with undercooked meat, poultry, or eggs, and unpasteurized dairy products. Symptoms can range from mild to severe, sometimes including bloody stools and high fever.
• Parasitic Infections: Parasites are less common than viruses or bacteria in developed countries but can still cause diarrhea, especially when traveling to areas with poor sanitation. Examples include Giardia lamblia, Cryptosporidium, and Entamoeba histolytica. These parasites are often contracted through contaminated water or food. Symptoms can include prolonged diarrhea, abdominal pain, nausea, and weight loss.

Non-Infectious Causes

Diarrhea isn't always due to an infection. Several other factors can contribute:

• Food Intolerances and Allergies: The inability to properly digest certain foods can lead to diarrhea. Lactose intolerance, the inability to digest lactose (a sugar found in milk and dairy products), is a very common example. Other intolerances include fructose or gluten (celiac disease is an autoimmune disorder triggered by gluten). Food allergies, while less common than intolerances, can also cause diarrhea along with other symptoms like hives or difficulty breathing.
• Medications: Many medications can cause diarrhea as a side effect. Antibiotics are particularly notorious for this, as they can kill off beneficial bacteria in the gut, disrupting the normal balance and leading to diarrhea. Other medications, including certain antacids containing magnesium, some chemotherapy drugs, and some antidepressants, can also trigger diarrhea.
• Digestive System Disorders: Chronic or recurring diarrhea can be a symptom of underlying digestive system disorders. These include:
  • Irritable Bowel Syndrome (IBS): A common disorder that affects the large intestine, causing cramping, abdominal pain, bloating, gas, and diarrhea or constipation, or both.
  • Inflammatory Bowel Disease (IBD): A group of chronic inflammatory conditions of the digestive tract, such as Crohn's disease and ulcerative colitis, which can cause diarrhea, often with blood and mucus, abdominal pain, fatigue, and weight loss.
  • Malabsorption Syndromes: Conditions where the small intestine cannot absorb nutrients properly, leading to various digestive issues including diarrhea.
• Artificial Sweeteners: Certain artificial sweeteners, like sorbitol, mannitol, and xylitol, which are found in sugar-free gums and candies, can have a laxative effect and cause diarrhea in some individuals.
• Other Medical Conditions: Less commonly, diarrhea can be a symptom of other conditions such as hyperthyroidism, certain types of cancer, or post-surgery complications.

When to Seek Medical Advice

While most cases of diarrhea resolve quickly, it's important to consult a healthcare professional if you experience any of the following:

• Diarrhea lasting longer than a few days (especially in infants or the elderly).
• Signs of dehydration (e.g., reduced urination, dry mouth, dizziness).
• Severe abdominal or rectal pain.
• Bloody or black, tarry stools.
• High fever (over 101.3°F or 38.5°C).
• If diarrhea occurs after recent travel to certain regions or after consuming potentially contaminated food or water.

Prompt medical attention can help identify the cause and prevent complications, particularly dehydration, which can be dangerous.