Causes of Diarrhea

Diarrhea - loose watery stools three or more times a day - is the gut's emergency flush response. Almost everything that causes it arrives through the mouth, which is why prevention is mostly about what goes in.

The infectious causes (the majority)

• Viruses: rotavirus in infants, norovirus in everyone - the commonest cause worldwide, self-limiting
• Bacteria: E. coli, Shigella, Salmonella, Campylobacter, cholera - from contaminated water, food and hands; these bring fever and sometimes blood
• Parasites: Giardia (the chronic bloating-traveler), amoeba (bloody mucus dysentery)
• The route is always the same: contaminated water, undercooked or street food kept warm too long, unwashed hands, unwashed raw produce

The non-infectious causes

• Food intolerances: lactose intolerance (milk triggers bloating and loose stools) is common in Indian adults
• Medicines: antibiotics (they clear gut bacteria along with the infection), antacids with magnesium, metformin, chemotherapy
• Chronic gut conditions: IBS, celiac disease, inflammatory bowel disease - when diarrhea lasts weeks, the hunt changes
• Anxiety and stress: the gut-brain axis is real - exam-day and interview-morning diarrhea proves it
• Excess artificial sweeteners (sorbitol in sugar-free gums), too much caffeine or alcohol

In children, the special notes

• Rotavirus dominates infant diarrhea - the vaccine prevents the severe form
• Teething does NOT cause true diarrhea - that myth delays real care
• Malnutrition and diarrhea feed each other in a vicious cycle - each episode weakens the child for the next

One-line summary

Diarrhea's causes are mostly swallowed: viruses, bacteria and parasites from contaminated water, food and hands - plus lactose intolerance, antibiotics, chronic gut conditions and stress; and in children, rotavirus, with teething falsely blamed.