Food Poisoning on Koh Samui: What to Do and When to See a Doctor

A dodgy meal is one of the most common ways a Koh Samui trip goes sideways. The good news is that most food poisoning and traveller’s diarrhoea clears up on its own within a day or two if you rest and rehydrate well. The important part is knowing the handful of warning signs that mean you should stop self-treating and see a doctor.

Where it usually comes from

The usual culprits here are undercooked seafood, street food that has sat in the heat, and ice made from unfiltered water. Bacteria like E. coli and Salmonella are common causes, and norovirus spreads easily in hotels and resorts. Symptoms typically start 2 to 48 hours after the contaminated meal.

What it feels like

Expect some combination of nausea, vomiting, watery diarrhoea, stomach cramps, and sometimes a mild fever, headache, muscle aches, dizziness or weakness. Unpleasant, but for a mild case, manageable at home.

How to manage a mild case yourself

If there is no fever and no blood, rest and rehydration are the whole plan. The key detail people get wrong: replace fluids with an oral rehydration solution (ORS) or electrolyte drink, not plain water — you are losing salts as well as fluid. Sip steadily rather than gulping. Once things settle, ease back in with bland foods like rice and toast, and skip alcohol, caffeine and dairy until you have fully recovered.

Red flags — see a doctor now

Stop self-treating and get medical help if you have any of these:

• Blood in your stool or vomit
• A fever above 38.5°C
• Diarrhoea lasting more than 48 hours
• Signs of dehydration — dizziness, dark urine, a very dry mouth
• Severe abdominal pain
• You cannot keep any fluids down
• The person affected is a young child, elderly, pregnant, or has a chronic condition

How we can help — and why the drip works so well

At the clinic we can rehydrate you with an IV drip, give anti-nausea medication so you can keep fluids down, test a stool sample, and add antibiotics only if a bacterial infection is confirmed. When you are too nauseated to drink, an IV bypasses the stomach entirely and puts fluids and electrolytes straight into the bloodstream — most people feel dramatically better within 30 to 60 minutes. If you cannot face the trip in, we will come to your hotel or villa.

Frequently asked questions

• Water or electrolytes? Electrolytes (ORS) — plain water alone does not replace the salts you are losing.
• When do I need antibiotics? Only if a stool test confirms a bacterial cause; they are not routine for food poisoning.
• How fast does an IV drip help? Usually within 30–60 minutes, because it skips the stomach altogether.
• Can you come to my hotel? Yes — home and hotel visits cover the whole island, ideal when travelling is the last thing you want to do.
• When is it an emergency? Blood, a high fever, or being unable to keep fluids down — come in straight away.

“Rehydrate with electrolytes, not just water — and if you cannot keep anything down, that is the moment to come in.”— Samui Home Clinic