Medically reviewed by Dr. Ponlawat Pitsuwan, Physician, Takecare Clinic Phuket. Last reviewed: September 2026.
Mosquito and sand fly bites are a part of life in Phuket, and most settle with simple care. The problems I see come from scratching, which lets bacteria in, and from the occasional allergic reaction to bee or wasp stings, which needs prompt attention.
Bites are a daily part of island life, and the people who visit us about them are usually not in danger, just miserable. A common pattern is a guest who sat on the sand at Nai Harn or Bangtao for a sunset and woke up with dozens of maddening bumps around the ankles. Others come in after a bee or wasp sting on a jungle trek or waterfall visit, or with a bite that was scratched open and has turned red and sore. Our job is to separate the itchy from the infected and the allergic.
Who is biting: Phuket’s usual suspects
| Culprit | Typical bite or sting | Where and when |
|---|---|---|
| Mosquitoes | Itchy, raised pink bumps on exposed skin | Aedes by day, especially early morning and late afternoon; others at night |
| Beach sand flies | Clusters of tiny, intensely itchy bumps that appear hours later | Ankles and legs, on the sand around dawn and dusk |
| Fire ants and weaver ants | Burning pain; fire ants leave white pustules within a day | Lawns, gardens, trees and resort grounds |
| Bees, wasps and hornets | Sharp pain, a central mark, swelling; bees leave a stinger | Trails, waterfalls, outdoor bars with sweet drinks |
| Spiders | Two small puncture marks, local pain; true bites are uncommon | Shoes, towels and outdoor furniture |
| Bed bugs | Lines or groups of three or four bites | Overnight, on skin exposed in bed |
Thailand’s beach “sand flies” are mostly tiny biting midges whose bites flare that evening and itch for a week or more. Fire ant pustules are sterile, so leave them intact. Most local spiders are harmless, and a painful red lump blamed on a spider is more often a bacterial boil.
Normal reaction, large local reaction or allergy?
A normal reaction is an itchy bump that fades within a few days. A large local reaction is swelling of more than about 10 cm around the bite, peaking at 24-48 hours and lasting up to a week. A whole forearm or ankle can swell, which looks alarming, but this is a contained allergic-type response, not an infection, and rarely dangerous. Anaphylaxis is different: a whole-body reaction within minutes, usually after a bee, wasp or hornet sting, with spreading hives, swelling of the lips, tongue or throat, wheezing, vomiting or collapse.
When a bite becomes infected
Scratching breaks the skin and lets in bacteria, usually staphylococci or streptococci. Infection tends to show one to three days after the bite, when things should be improving: redness that keeps spreading, warmth, throbbing pain, pus, a honey-coloured crust (impetigo) or a red line tracking up the limb. Fever or feeling unwell suggests the infection is spreading. These bites need a doctor, and our page on skin infection treatment explains cellulitis and impetigo in detail.
Mosquitoes, dengue and fever after a bite
A mosquito bite that carries an infection looks exactly like any other bite, so the rash itself tells you nothing. Dengue is spread by the day-biting Aedes mosquito and occurs in Phuket all year, with more cases in the rainy season. Symptoms usually begin 4-10 days after the infecting bite: high fever, severe headache, pain behind the eyes, muscle and joint aches and sometimes a rash. Take paracetamol only, and avoid ibuprofen, aspirin and other anti-inflammatory painkillers, which raise bleeding risk. Our page on dengue fever treatment covers testing and warning signs. The same mosquito spreads chikungunya and Zika, while malaria risk in Phuket itself is very low.
How we treat bites and stings
We look at the pattern of bites, which often identifies the insect, and check for infection or signs of allergy. A retained bee stinger is scraped out sideways. Itch is controlled with a non-drowsy antihistamine such as cetirizine, loratadine or fexofenadine, sometimes with a sedating one such as chlorphenamine at night, plus a steroid cream. Hydrocortisone 1% suits mild bites, and a stronger prescription steroid helps sand fly clusters. A severe large local reaction may need a few days of oral prednisolone. Antibiotics are only for infected bites: usually flucloxacillin or cefalexin, or clarithromycin with a penicillin allergy. If you have a fever, we can run an NS1 dengue antigen test and a full blood count in our on-site laboratory, with same-day results.
Safe self-care at your hotel
Wash bites with soap and water, then hold a cold, damp cloth on them for 10 minutes. Keep nails short, and cover bites at night if you scratch in your sleep. Calamine lotion or a pharmacy antihistamine helps with itch. Raise a swollen hand or foot on a pillow. After a bee sting, remove the stinger quickly, as it keeps pumping venom for a short time.
When to see a doctor
See us if a bite is getting worse after two days, if swelling spreads beyond the joint nearest the bite, if you have many stings, or if a bite on the face or near the eye swells. Multiple hornet or wasp stings can harm the kidneys and muscles even without allergy.
Prevention and early detection
Use a repellent containing DEET at 20-50%, picaridin (icaridin) at about 20% or IR3535, applied after sunscreen. Remember that Aedes bites in daylight, so repellent matters at lunch and on shopping trips, not just at dusk. At a villa, empty standing water in plant saucers, vases and buckets, and sleep with air-conditioning or a net. For sand flies, sit on a lounger rather than directly on the sand at dawn and dusk. Cover sweet drinks outdoors and shake out shoes before wearing them.
Seeing our team about a bite or sting
We are open 24 hours at our Bangtao (Cherngtalay) clinic, Kata-Karon clinic and Patong clinic. A walk-in doctor in Phuket visit needs no appointment and usually takes under 30 minutes, and our on-site pharmacy has the usual creams and tablets. For a doctor hotel visit in Phuket, message us on WhatsApp or call +66 81 718 9080. We confirm the price on WhatsApp before your visit, bill most travel insurers directly and supply receipts, a medical report and an itemised invoice.
Related services and treatments
If you have reacted badly to stings before, our allergy treatment service can review whether you should carry adrenaline. Burning welts after swimming need jellyfish sting treatment rather than bite care, and burnt skin scratched raw heals better with proper sunburn treatment. An itch that keeps spreading, worst at night and between the fingers, may be mites needing scabies treatment, while burning pain followed by a one-sided band of blisters suggests shingles treatment. You can also browse the conditions we treat.
Summary
Most bites in Phuket are harmless but itchy, and respond to an antihistamine, a steroid cream and not scratching. Watch for three things: spreading redness or pus that signals infection, swelling or breathing trouble that signals allergy, and fever in the following two weeks that could be dengue. Use repellent in daylight as well as at dusk.
“Use a repellent containing DEET or picaridin, especially at dawn and dusk. Try not to scratch bites, because broken skin infects easily in the heat.”
Dr. Ponlawat Pitsuwan, Physician, Takecare Clinic Phuket
Frequently asked questions
Is a visit for an infected bite covered by travel insurance?
Treatment for an infected bite or allergic reaction is usually covered as an unexpected medical problem, though excesses and terms vary by policy. We bill most travel insurers directly, and if yours does not, we give you receipts, a medical report and an itemised invoice to claim. We confirm the price on WhatsApp beforehand.
Can I just walk in with a sting, or do I need an appointment?
Just walk in. None of our three clinics require an appointment, and they are open around the clock. Walk-in patients are usually seen within minutes, and most bite or sting visits take under 30 minutes. If a sting is followed by breathing trouble or throat swelling, call 1669 rather than travelling to us.
Can a doctor come to my hotel to look at my bites?
Yes. A doctor can visit your hotel or villa anywhere in Phuket, day or night, examine the bites, check for infection or allergy and leave the medicines you need. This suits families with several itchy children or anyone with a swollen foot who cannot walk easily. Message us on WhatsApp with your location.
My ankle has swollen hugely after a bite. Is it infected or allergic?
Swelling that appears within a day, itches more than it hurts and is worst at 24-48 hours is usually a large local allergic reaction. Infection tends to appear later, after one to three days, with increasing pain, heat, pus or fever. The two can look similar, so if you are unsure or it keeps spreading, let a doctor examine it.
Can I tell from the bite whether a mosquito has given me dengue?
No. An infected bite looks identical to any other, and symptoms only appear 4-10 days later as a sudden high fever with headache and body aches. If that happens, see a doctor for an NS1 antigen test and blood count, and take paracetamol rather than ibuprofen or aspirin while you wait.
Should I carry an adrenaline pen after a bad reaction to a sting?
If you have had a whole-body reaction, such as throat swelling, wheezing, fainting or widespread hives, you probably need an adrenaline auto-injector and a referral to an allergy specialist at home. A large swollen area around the sting alone does not usually mean you need one. A doctor can assess your particular risk.
Sources
The NHS covers self-care and warning signs for insect bites and stings and explains how to recognise anaphylaxis. The World Health Organization fact sheet on dengue and severe dengue describes symptoms and mosquito control.
Insect bites, bee and wasp stings, mosquito bite, Aedes aegypti, sand fly bites, biting midges, fire ants, bed bugs, large local reaction, anaphylaxis, impetigo, dengue, NS1 antigen test, cetirizine, loratadine, hydrocortisone, prednisolone, flucloxacillin, adrenaline, DEET, picaridin, NHS, WHO, Takecare Clinic Phuket, Bangtao, Nai Harn, Kata, Patong, Dr. Ponlawat Pitsuwan
This page is general health information and not a substitute for a medical consultation.