What Causes Diarrhea After Eating?

A single attack (or few attacks) of diarrhea, appearing few minutes to few hours after eating may be due to:

• Wrong food combination - some foods just don’t go together, like meat and sugar… 
• Magnesium in some mineral waters, sport drinks, antacids, supplements
• Staph food poisoning with toxins released from bacterium Staphylococcus aureus; diarrhea may appear from 20 minutes to 8 hours after ingesting contaminated food (in food poisoning due other bacteria, viruses, or parasites, diarrhea usually appears over 8 hours after the meal)

Diarrhea after a meal, occurring on a long term, may be due to:

• Food allergy: tingling around the mouth or in the throat, hot facial flushes, hives with skin itching and diarrhea may appear in the first minute after food ingestion, or may appear several hours later
• Lactose intolerance: bloating and/or diarrhea may appear after eating dairy or any other food containing lactose
• Rapid gastric emptying - dumping syndrome
• Irritable bowel syndrome (IBS) - urge for defecation may appear immediately after the meal
• Toddler’s diarrhea is due to overfeeding of toddlers with fruit juices – toddler is otherwise healthy 
• Fructose malabsorption- bloating and/or diarrhea may appear in few hours after ingestion fruits, honey, or other foods containing fructose, sorbitol, xylitol, or HFCS
• Short bowel syndrome (SBS)

Further Reading:

Cure for Diarrhea
Causes of Sudden (Acute) Diarrhea
Normal Bowel Movement Color
Mucus in Bowel Movement
Blood in Your Stool