Thailand: islands, health and roads, what the official advisories say

Thailand's islands are postcard material, but a beach trip has small print: the rainy calendar, the state of the sea, hire motorbikes, boats between islands or the air quality in the north. This guide complements our three earlier guides (entry, laws and Bangkok at night) with what the UK Foreign, Commonwealth & Development Office (FCDO) safety and health advice, consulted in November 2026, records. It does not replace your own country's advice.

Calendar and climate: the whole country does not rain at once

The advice explains that the rainy season generally runs from May to October, with possible flash floods and landslides, especially in the north, north-east and mountainous areas, where lakes, caves and waterfalls are particularly dangerous. But there is an important exception: in Koh Samui and south-east Thailand the rainy season runs from November to March. If you plan to combine Phuket with Koh Samui, this fact can help you choose dates.

The sea: jellyfish and currents

From May to October there may be jellyfish near the shore, and their stings can be fatal. Strong rip currents have caused drownings, especially in monsoon season. In practice: respect the flags, ask where you are staying about each day's conditions, do not swim alone or at night and, if you see a red flag, leave the photo for another day.

Boats between islands

Boats between the mainland and islands can sink or collide, often through overloading, poor maintenance or rough seas. Choose serious operators, check that life jackets are on board and do not board a visibly overloaded vessel. If the weather is bad, postpone the crossing.

Hire motorbikes: the big trap

According to the advice, the WHO ranks Thailand among the countries with the most motorcycle deaths. Many hire bikes in tourist areas are unregistered and not legal on public roads. To drive you need the 1968 international permit as well as your licence (it cannot be obtained outside the UK in the British case; check which applies to your country), helmets are mandatory and riding without a valid licence can void your insurance. Never leave your passport as security: the business may keep it against claimed damage. A hire motorbike is usually an avoidable risk; a taxi or private driver is not.

Drinks, nightlife and events

Drink spiking and drug-assisted sexual assaults occur in tourist areas, with victims of both sexes. Violent and sexual assaults are more common at mass parties such as full moon events and near bars late at night. Keep your drink in sight, refuse drinks from strangers and arrange your return. Bar drinks are often stronger than at home, and methanol in counterfeit drinks has caused deaths (it cannot be detected by taste or smell). Alcohol sales are restricted between midnight and 11:00, except at licensed hotels, international airport terminals and authorised venues.

Money and scams

ATM skimming occurs: use bank ATMs, keep your card in sight and protect your PIN. Distrust well-paid job offers in neighbouring countries: they have led to passport confiscation, poor conditions and coercion into online scamming.

Health and hospitals

Check vaccinations on TravelHealthPro and your country's health services at least eight weeks ahead. Dengue, rabies and malaria are listed as risks; hospitals require a payment guarantee before treating you; private facilities are high quality but expensive; and public ones do not always meet UK standards, especially outside Bangkok. Take out insurance with medical and evacuation cover, especially if you have a pre-existing condition or are pregnant. Ambulance calls go to 191 (the local number is 1669), according to the FCDO. Street medication may be fake or stolen. Medicines from your country may have a different legal status in Thailand.

Air

Chiang Mai and Bangkok suffer high pollution, with regional haze from crop and tree burning that can reach dangerous levels and worsen bronchial conditions or asthma. If either of you has respiratory problems, check the air before fixing dates. More in our Chiang Mai for couples page.

Useful rules people forget

You may not carry more than 120 playing cards (Playing Cards Act 1943). Drones must be registered with the NBTC within 30 days of entry or purchase; an unregistered drone can mean a fine of 100,000 baht, five years' imprisonment or both. Police may ask to see your passport; if you do not have it, you could be asked to produce it at a police station within 24 hours (a copy of the photo page is usually enough). And vaping, photographs and cannabis are in our laws guide.

What we do not publish

BarSwinger lists no nightlife venues on Thailand's islands because we could not verify any with a live official website. Nor do we give space to anything suggesting sex tourism or exploitation. If you are looking for accommodation, choose establishments with an official website and a clear policy.

Frequently asked questions

Which month is best for Koh Samui? The advice puts its rains from November to March; outside that window the weather tends to be steadier. Check the forecast before booking.

And for Phuket? The general rainy season runs May to October, with jellyfish and strong currents.

Whom do I call in a medical emergency? The FCDO gives 191 for an ambulance and 1669 as the local number.