Watery diarrhea is loose, runny stool that pours out rather than holds shape. It happens when the gut lining pumps extra fluid into the bowel or fails to soak up the fluid already there. Common triggers fall into five big groups:

1. Viruses
   Rotavirus, norovirus, and adenovirus top the list. They strike fast—often within 24 hours of contact—and usually clear in a few days.
2. Bacteria
   Some germs make toxins that force the gut to secrete water (cholera-like). Others, such as certain strains of E. coli, Campylobacter, and Salmonella, damage the lining itself. Typical story: under-cooked poultry, raw eggs, or street food eaten 6–72 hours before symptoms start.
3. Parasites
   Giardia and Cryptosporidium hang out in streams, pools, or daycare centers. They can cause weeks of watery stools, gas, and weight loss.
4. Diet and drugs
   Huge doses of vitamin C, magnesium, or sorbitol-sweetened gum pull water into the bowel. Antibiotics wipe out normal bacteria and let tougher bugs multiply, leading to antibiotic-associated diarrhea.
5. Chronic conditions
   Irritable bowel syndrome can produce urgent, watery movements, especially in the morning or after coffee. Celiac disease, microscopic colitis, and overactive thyroid also keep stools loose for months if not treated.

Red flags that mean “see a doctor today”:

• Blood or pus in the stool
• Fever over 38.5 °C (101.3 °F)
• Signs of drying out: dizzy when standing, dry lips, little or no urine
• Diarrhea lasting more than two days in babies, elderly, or anyone with chronic illness

Home care basics: sip water, broth, or an oral rehydration drink every few minutes; eat bland carbs (rice, toast, bananas) once vomiting stops; wash hands often to protect everyone else.