The CDC lists no malaria pills for Phuket and Krabi. The day-biting dengue mosquito is the one to plan for.
- No CDC travel notice for mosquito-borne disease
Thailand's disease control department named Phuket among the five provinces with the highest dengue rates in July 2026, in a year running well below 2025 nationally. The CDC recommends no malaria medicine for this coast, and sandflies turn up on some quieter beaches at dawn and dusk.
Yes. Phuket, Krabi and the islands around them have the day-biting Aedes mosquito that spreads dengue, and in July 2026 Thailand's Department of Disease Control named Phuket among the five provinces with the highest dengue rates. The CDC recommends no malaria medicine for Phuket, Krabi or its islands, so the job is a daytime repellent habit plus some care on quieter beaches at dawn and dusk.
Dengue is the one to plan for
In its July 27, 2026 release, the Department of Disease Control ranked Phuket second among the five provinces with the highest dengue rates over the previous four weeks, after Satun. Nationally the year is quieter. The department counted 25,026 cases and 39 deaths by September 15, about 1.8 times fewer than in 2025, but said cases were still trending up, especially in the south. By mid-October, the World Health Organization's weekly count for Thailand was 41% below the same week of 2025, though recent weeks can still be revised.
The mosquito behind it bites in daylight around towns and resort gardens, so put repellent on over sunscreen in the morning, again after swims and boat trips, and again before the late-afternoon peak. Our dengue & Zika routine has the full schedule. The same mosquito carries chikungunya, which the CDC rates an elevated risk in Thailand, and Zika, which circulates at low levels.
The CDC lists no malaria pills for this coast
The CDC's Thailand page reports "rare to few cases" of malaria "on the islands of Koh Pha Ngan, Koh Samui, or Phuket" and "No malaria transmission on the islands of Krabi Province (Koh Lanta, Koh Phi Phi, Koh Yao Noi, Koh Yao Yai)." Phuket, mainland Krabi and Phang Nga don't border Myanmar, Cambodia or Malaysia, so the CDC's line for "All other areas with malaria transmission" applies: "No chemoprophylaxis recommended (insect bite precautions and mosquito avoidance only)."
The CDC does list medicine for the border provinces, so adding Koh Chang or a trek outside Chiang Mai makes it a travel-clinic question. Our Thailand briefing maps the whole country, and the Chiang Mai briefing covers the north. Yellow fever vaccine is not recommended, and Thailand asks for proof only from travelers arriving from countries with yellow fever risk, including layovers of more than 12 hours there.
Sandflies and the beach you pick
On some quiet, unraked beaches, tiny biters that locals call sandflies come out at dawn and dusk and in still air. Our Thailand briefing treats them as biting midges, the weak-flying no-see-ums that go for ankles and lower legs. They're patchy. Busy, raked hotel beaches such as Patong, Kata and Ao Nang draw fewer complaints than the bungalow beaches on smaller islands like Ko Jum. Treat ankles and calves before you sit on the sand early or late, and pick a raked or breezy stretch. Our Barbados sandfly guide explains how they behave.
Stinging water is a separate problem, generally blamed on tiny jellyfish or anemone larvae rather than insects, and repellent is unlikely to help.
When to go
The Andaman coast's dry, calm season runs roughly November to April, the best stretch for beaches and for bites. The southwest monsoon brings rain and rough seas roughly May to October, overlapping the rainy months when Thailand's dengue usually rises. Dengue is reported in every month, so a January beach week still needs the morning repellent.
Where you're going
How the main bases compare.
Patong, Karon & Kata
Busy, raked beaches where sandfly complaints are rare. The CDC reports rare to few malaria cases on Phuket and recommends no medicine, so the dengue mosquito in town and in resort gardens is the one to cover for.
Koh Lanta, Koh Phi Phi & the Krabi islands
The CDC reports no malaria transmission on the islands of Krabi Province. Quieter, unraked bungalow beaches are where sandflies tend to turn up, so treat ankles before you sit on the sand at dawn or dusk.
Ao Nang & Railay
Mainland Krabi isn't named by the CDC and falls under its line for the rest of Thailand, with no malaria medicine recommended. The busy beaches here tend to draw fewer sandfly complaints than the small islands.
Khao Lak & Phang Nga Bay
Phang Nga is not a border province, so the CDC recommends no malaria medicine. Phang Nga Bay and Similan day boats spend most of their hours on the water, which likely means fewer bites than a day by the pool.
The Andaman coast kit
- Picaridin 20% travel sprays: odorless in the heat, layers over sunscreen and deters sandflies as well as mosquitoes. One 3.4 oz bottle covers about a week of daily use for one person.
- A full-size backup in the checked bag. Reapplying after every swim and boat trip goes through a bottle fast.
- Light long pants or socks for dawn and dusk on the quieter beaches.
What travelers report
Paraphrased from TripAdvisor forum threads and linked so you can read them in full. None is dated, and both sandflies and stinging water come and go with the beach, the tide and the weather.
- Krabi and nearby islands · January (dry season)
In a thread asking about sandflies in January, a poster said they had seen no sign of them anywhere around Krabi and the nearby islands over several dry-season trips. TripAdvisor ↗
- Patong, Karon and Kata, Phuket
Posters described stinging 'sea lice' in the water: one said it happened almost every time they swam at Patong, and another group was stung at Karon and Kata. TripAdvisor ↗
- Koh Lanta (Long Beach, Klong Nin)
Posters described sea-lice stings while swimming that came and went with conditions; one said the bites were itchy rather than painful, and another needed antibiotics and steroid cream. TripAdvisor ↗
One rule outlasts the trip. Any fever during or after your trip means a doctor visit, and you tell them you were in Thailand. Thailand's Department of Disease Control advises paracetamol rather than ibuprofen or aspirin until dengue is ruled out.
Traveler questions
Do I need malaria pills for Phuket or Krabi?
The CDC recommends no malaria medicine for Phuket, Krabi or Phang Nga. It reports rare to few cases on Phuket and "No malaria transmission on the islands of Krabi Province (Koh Lanta, Koh Phi Phi, Koh Yao Noi, Koh Yao Yai)," and for the rest of this coast its line reads "No chemoprophylaxis recommended (insect bite precautions and mosquito avoidance only)." The CDC does list medicine for the provinces that border Myanmar, Cambodia (except Buri Ram) and Malaysia, so if your trip adds Koh Chang or a trek outside Chiang Mai, see a travel clinic 4–6 weeks before departure.
Is dengue high in Phuket right now?
Thailand's Department of Disease Control ranked Phuket second among the five provinces with the highest dengue rates over four weeks in July 2026. Nationally the year is running well below 2025, with 25,026 cases by September 15, about 1.8 times fewer, though the department said cases were still rising in the south. There is no CDC travel notice for Thailand. The dengue mosquito bites by day, so wear repellent from the morning on.
When is the best time to visit Phuket for fewer mosquitoes?
Roughly November to April, the Andaman coast's dry, calm season. The southwest monsoon, roughly May to October, brings rain and rough seas and overlaps the months when Thailand's dengue usually rises. Dengue is reported in every month, so keep the daytime routine whenever you go.
Is it safe to visit Phuket while pregnant?
Zika circulates in Thailand at low levels. The Department of Disease Control counted 245 cases nationwide in 2025, across 43 provinces, and 43 in 2026 as of April 1, without a breakdown by province. There is no CDC Zika notice for Thailand, but the CDC lists Zika among the diseases for travelers there, including spread from a pregnant woman to her baby. If you're pregnant, talk to a healthcare provider before you go.
Sources
Health authorities, surveillance reports and news coverage of official bulletins used for this briefing, last checked October 2026. Traveler reports are linked where they appear. This page summarizes public-health guidance and is not medical advice.