Stop all solid food. Sip small amounts of water or ORS (oral rehydration salts) every 5–10 minutes. Avoid sugary drinks, alcohol and caffeine.
Rest flat. Track vomiting, diarrhea frequency, fever, and pain location. Most mild cases improve in 12–24 hours.
Any 7-Eleven or pharmacy sells ORS sachets for ~15 THB. Mix with clean bottled water. This replaces salts lost to diarrhea.
Bloody stool, fever above 39°C, severe abdominal pain, no urination for 8+ hours, confusion, or signs in children or elderly — go to hospital now.
If symptoms last more than 48 hours or worsen, visit any private hospital (Bangkok Hospital, Memorial, BNH). GP consultation is usually 700–1,500 THB.