The islands around Phang Nga and Krabi shine with that fierce, postcard light travelers chase. It’s the kind of light that warms the bones and betrays the careless. Every high season, I see the same pattern at the clinic on Koh Yao: sunburned shoulders that look like boiled prawns, hikers dizzy on the pier stairs, boat crews keeping quiet about pounding headaches while they unload crates. Heat and sun are not abstract risks. They are conditions that nudge the body past its margins, slowly at first, then all at once.
I have practiced family and emergency medicine in Southeast Asia long enough to know that most sun and heat injuries are preventable, and that early, well-judged care turns a miserable day into a survivable story. What follows blends clinical guidance with practical details I use with patients, guides, and resort staff. If you are planning long days outside, or you look after those who do, treat this as a field manual you can remember without a signal or a search bar.
How sunburn actually happens, and why it can be worse than it looks
Sunburn is a radiation injury. Ultraviolet B penetrates the epidermis and creates direct DNA damage, while UVA stirs up oxidative stress deeper in the skin. The body’s response arrives on a delay, which is why you may feel fine during a snorkel trip at noon and only realize the damage at dinner. That delay tricks people into thinking they have a higher tolerance than they do.
Severity lives on a spectrum. Mild sunburn shows as redness, heat, and tenderness. Moderate burns add swelling and tightness, sometimes chills and low-grade fever. Severe burns bring blisters, widespread swelling, and systemic symptoms, from nausea to racing heart. I have admitted travelers with second-degree burns to large areas because they underestimated cloud cover, wind, or reflection off the sea. Do not mistake the absence of visible peeling for safety. The injury is already underway long before the skin flakes.
Two local factors on Koh Yao accelerate burn and confusion. First, reflection off the water and white sand effectively doubles exposure, especially on a long-tail boat or a paddleboard. Second, the breeze on the bay cools the skin and masks overheating, so people skip breaks. A good rule I teach boat crews: if a tourist’s skin is the color of a raw lobster, you don’t need a thermometer to recommend the shade.
Sunscreen works, but only if you treat it like medication, not paint
People ask me which SPF number is best. The number measures UVB protection in lab conditions, not in a humid, sweaty reality. What matters more is the amount, reapplication, and timing. Use a broad-spectrum sunscreen labeled for both UVA and UVB. SPF 30 blocks around 97 percent of UVB, SPF 50 around 98 percent. That one percent feels comforting, but if you do not apply enough, both perform poorly.
I advise a simple dosing rule that sticks: use a shot glass worth of sunscreen for the body and a teaspoon for the face and neck. Apply 20 to 30 minutes before you step into strong light, then reapply every two hours, or after swimming, sweating, or towel drying. Spray formulas are fine if you rub them in and use plenty. Check the ears, the lips, the tops of feet, and the scalp part. I treat more burned earlobes than you might think.
If you prefer mineral sunscreens with zinc oxide or titanium dioxide, expect a bit of a cast on darker skin tones. On excursions, I use mineral sticks on the nose, cheekbones, and ears, then a fluid formula elsewhere. Hats and clothing beat any SPF when the sun is high. A tightly woven long-sleeve shirt with a collar and a brimmed hat will reduce risk more than the fanciest cream on its own.
The quiet role of time of day, cloud cover, and latitude
I ask visitors to think of sunlight like a tide, not a switch. UV intensity climbs through the morning, peaks around midday, and falls toward evening. On Koh Yao, where we sit close to the equator, the peak is sharp, and the fall is slower than you expect. Cloud cover can reduce some direct UV but may increase diffuse UV, which still burns. I have seen more than a few epic burns that happened during a “cloudy day,” with victims lulled out to sea by a gentle gray dome.
Plan your longest exposure early morning or late afternoon. It’s reasonable to snorkel at 9 a.m., break from 11 to 2, then kayak at 4. I use that exact plan myself when off duty. If your schedule is fixed, rotate shade breaks every 20 to 30 minutes, even if you feel fine. The body has a delayed feedback loop with sun and heat. Take control of the schedule rather than waiting for symptoms.
When a sunburn needs more than aloe and a shrug
Most sunburns respond to simple home care, and I will outline that in a moment. Still, there are signs that should push you to seek clinical care. If more than 15 to 20 percent of your body is blistered, if the pain makes you lightheaded, if you have fever over 38.5 C, or if the burn involves the eyes, go in. I have also learned to ask about medicines. Doxycycline, certain acne medications like isotretinoin, and even some herbal extracts increase sun sensitivity. If you are on these, sunburn can arrive faster and bite harder.
Older adults, people with chronic skin conditions, and children get dehydrated more easily after a burn. If a child cannot sleep because of pain, or refuses fluids, that is not a wait-and-see situation. We can help with pain control and hydration at the clinic. If you see streaks of redness spreading from a blister, or the area becomes hot and more tender after a few days, think infection and get checked.
What I actually prescribe for an acute sunburn
I begin with temperature. Cool, not cold. A 10 to 15 minute cool shower or compress reduces heat in the skin and eases pain, but ice worsens tissue injury and can shock. Pat dry rather than rubbing.
Next is a bland, generous moisturizer. I prefer fragrance-free creams or gels. Aloe vera works well if it is unscented and not mixed with alcohols or menthol. Some patients have mild reactions to additives, which just pile irritation on injury. For a moderate burn without blisters, a short course of a low to medium potency topical steroid reduces inflammation when started within the first 24 to 48 hours. I reach for hydrocortisone 1 percent twice daily for two to three days, then stop. Not everyone needs this, but in my experience it shortens the miserable window.
Pain control matters more than pride. A nonsteroidal anti-inflammatory like ibuprofen, with food and within labeled dosing, helps both pain and swelling. It is not magic, but it moves people from sleepless to functional. I advise against topical anesthetics with benzocaine or lidocaine on large areas. They can trigger allergic reactions and are easy to overuse. If blisters form, do not pop them. That thin roof protects against infection. If a blister tears, clean with mild soap and water, then a light layer of petrolatum and a nonstick dressing. Change daily.
Hydration is not just for the mouth. A sunburn draws fluid into the skin and increases overall fluid loss. I suggest adding an oral rehydration solution or a homemade mix of a pinch of salt and sugar in a liter of clean water for a day or two after a significant burn. Avoid heavy alcohol until the skin calms. If nausea or dizziness appears, treat it like a heat issue too, which brings us to the other half of the story.
Heat exhaustion and heatstroke share the same road, just different mile markers
Heat injuries begin when the body’s cooling machinery cannot keep up. Sweat evaporates to carry heat away. When humidity is high, sweat sits on the skin and evaporation slows. On Koh Yao, humidity often lives above 70 percent. Add full sun, hard work, and low airflow and you have an oven you can walk through.
Heat stress unfolds along a spectrum. Heat cramps, the early warning, are painful spasms in the calves, thighs, or abdomen, usually during or after exertion. Heat exhaustion brings heavy sweating, weakness, headache, nausea, lightheadedness, and a fast pulse. Heatstroke is a medical emergency. The core temperature rises above 40 C, the central nervous system falters, and the skin may be hot and dry or, sometimes, still damp. Confusion, agitation, collapse, or seizures can appear without much warning.
From the clinic side, the boundary between exhaustion and stroke matters less than action. I tell resort staff to treat significant symptoms with urgency, because a person can move from one state to the other in minutes if the heat load continues. By the time someone appears confused, it is too late for gentle steps.
The island pattern: who gets into trouble and why
Tourists run into heat exhaustion when snorkeling late morning, then hiking to a viewpoint without a break. They often mistake thirst and headache for mild jet lag or a hangover. Fishermen and construction workers push through midday because the job demands it. They respect the sun, but the economics are not in their favor, and quiet dehydration builds across the week. Guides get caught when they spend the day caring for clients and forget their own pacing.
The highest-risk moments cluster around day three to five of a stay. The body has shaken off travel fatigue, confidence is up, and the local heat feels familiar enough to ignore. The kidneys and muscles have not had time to fully adapt. I see the result when a strong guest collapses on the pier stairs with a blank stare. Often there was little warning beyond a light nausea and a sense of “hitting the wall” that they wrote off.
Immediate field care for heat illness that works in our climate
Speed beats perfection. When I care for someone in the field, I use the gear I have in a bag, on a boat, or in a kitchen. The objective is to lower core temperature and maintain circulation without delay. Move the person to shade, remove excess clothing, and start aggressive cooling. Cool water poured onto the skin with fanning is simple and effective. Evaporation works even in humidity if you keep the air moving. Ice on the neck, armpits, and groin helps if available, but I will take wet towels and a hand fan over waiting for an ice bucket.
If the person is awake and not vomiting, give cool fluids with electrolytes. Water alone is better than nothing, but for heavy sweat loss, salt and sugar speed absorption. If there is vomiting, do not force fluids. Focus on cooling and transportation. Measure temperature if possible, but do not delay treatment while looking for a thermometer. I would rather see a slightly over-cooled person than a timely measurement with no action.
If mental status is altered, or temperature is likely above 40 C, arrange immediate transport to medical care. On Koh Yao, that might mean a pickup to the clinic or a fast boat to a hospital, depending on the time of day and severity. Cooling should continue during transport. I have cooled patients with a garden hose in the shade behind a kitchen while we waited for a vehicle, and it made the difference.
What to expect at a clinic visit for heat illness
Patients sometimes worry we will do something dramatic or invasive. Most often, we check vital signs, assess hydration, and start oral or intravenous fluids based on symptoms. If there are cramps, we stretch and massage gently and correct electrolytes. For heat exhaustion without concerning features, people recover within a few hours with fluids, rest, and cooling.
Heatstroke is different. We monitor temperature continuously, use more aggressive cooling, run blood tests to check kidney function and muscle breakdown, and admit for observation. Rhabdomyolysis, where muscle tissue breaks down and releases myoglobin, can injure the kidneys if not recognized and treated. I have seen it in fit travelers who ran hard in the sun after a long flight and little sleep. They looked sunburned and cheerful at first, but their urine turned dark and their legs felt like lead by evening. Do not ignore dark urine after heavy exertion in heat. Come in.
A simple framework to pace your day and prevent both sunburn and heat illness
Prevention works when it fits real life. I suggest a rhythm that honors local conditions. Start early, aim your longest outdoor blocks between sunrise and late morning, and plan a strong midday intermission with shade, fluids, and lighter activity. Reemerge in late afternoon. Build shade into your movement. If you are on the water, rotate positions so no one, including the guide, stays in the bow under full glare for hours.
Hydration aims for steady, not heroic. If your urine is pale yellow by mid-morning and stays that way, you are likely on track. Over-drinking just water can dilute sodium and make you feel worse. Add electrolytes during long efforts. Eat light, salty foods with real calories. Alcohol and heavy meals at noon stack the deck against you when the sun peaks.
Clothing choices matter more than you might think. Light, loose, tightly woven fabrics cover better than thin, sheer cotton that lets UV through. A brim wider than your palm protects ears and neck far better than a baseball cap. Polarized sunglasses protect eyes from glare and aggressive UV. After many seasons, my favorite sun gear is a long-sleeve UPF shirt with a high collar, a neck gaiter I can wet and drape, and a crushable hat I am not afraid to soak.
Case snapshots from the island that linger in my mind
A British couple arrived for a half-day island hop. The husband, fair-skinned, decided to “toughen up” with no shirt. The boat anchored in a calm, glassy cove. Four hours later he walked into clinic koh yao with chills, a heartbeat above 110, and sheets of tight, red skin. He was embarrassed more than worried. We cooled him, gave oral fluids, hydrocortisone cream, and a short course of ibuprofen. He came back the next day asking for a soft shirt and a hat recommendation. Two days later he brought the boat crew cold sodas and promised to listen the first time.
A dive master in her thirties fainted on the dock after her second trip of the day. She had spent hours supervising students in surface drills, calling out instructions in full sun, and forgot that mentors need the same breaks they insist on for students. Her core temperature was borderline, she had mild cramps, and her blood pressure recovered with rest and fluids. She admitted she avoided drinking much because she did not want to disrupt the group with bathroom breaks. We built a break schedule and a rotation with her team. The rest of the season ran clean.
A construction worker from the mainland came in after two days of nausea, dark urine, and thigh pain. He had been carrying cement bags in a half-finished building with poor airflow. His labs showed elevated muscle enzymes and kidney stress. We admitted him, cooled, hydrated, and monitored. He recovered, but his case prompted the site manager to move heavy tasks to the morning and add mandatory shade and electrolyte breaks. Sometimes one person’s illness improves conditions for dozens.
The kids, the elders, and the medications that change the equation
Children have higher surface area relative to mass. They heat and cool faster, and they do not pace themselves. They also cannot always express thirst or early symptoms. A simple rule I give parents: shade and fluids every 20 minutes when the sun is high, and apply sunscreen before you reach the beach. Reapply after they rub sand on themselves, which they will. I prefer rash guards and hats for children over relying on lotions.
Older adults may have reduced thirst signals and take medicines that complicate heat responses. Diuretics, beta blockers, anticholinergics, and some psychiatric medications reduce sweating or alter heart responses to heat. If a family brings grandparents to the islands, I ask them to review medications with a clinician ahead of time and adjust activity plans. The same goes for people with diabetes or heart disease. They can enjoy our bays and beaches safely with planning, but they do better with morning swims and shaded walks than midday peaks.
Photosensitizing drugs deserve special mention. Doxycycline, used for acne or infections, and thiazide diuretics can turbocharge sunburn. St. John’s wort, an herbal antidepressant, can do the same. If you are on these, clothing and shade are your friends. Do not test your limits.
How recovery actually plays out, day by day
After a moderate sunburn, expect the first 24 to 48 hours to be the hardest for pain and swelling. Then itching takes the baton. Gentle moisturizers, short cool showers, and patience help. Peeling starts around day three to five. Do not pick, as tempting as it is. New skin is fragile and prone to pigment changes. Avoid strong sun for at least a week to reduce long-term marks.
After heat exhaustion, most feel normal within a day or two if they rest and hydrate. If you feel wiped out for longer, it is not weakness. The body has absorbed a blow. Take it as a message to reduce intensity for several days. If you had heatstroke or rhabdomyolysis, we will guide your return to activity much more slowly.
The quiet differences between sun rash, prickly heat, and true burns
Not all red, irritated skin in the tropics is sunburn. Polymorphous light eruption, sometimes called sun allergy, shows as itchy bumps or plaques hours after exposure, often on the forearms, chest, and neck. It may burn mildly or not at all. Prickly heat, or miliaria, is common in our humidity. Sweat ducts clog and tiny, itchy bumps appear under clothing, especially where straps or waistbands sit. Treatment differs. Shade, cool compresses, and anti-itch lotions help. Heavy oils make prickly heat worse. If you are unsure, pop into a clinic for a quick diagnosis. I have saved many trips from misery by switching someone from the wrong cream to the right one.
Why the basics still outperform gadgets
Every season someone brings a novel cooling device or a sunscreen with a futuristic claim. Many work in narrow settings, then fall short at a beach or a trail. What holds up year after year are simple, repeatable habits. Start early, schedule shade, hydrate with electrolytes, cover up, reapply sunscreen like medicine, and listen to early symptoms. Technology can assist, but it cannot outwit physics.
A compact checklist you can remember
- Apply broad-spectrum SPF 30 or higher 20 to 30 minutes before sun, use enough, and reapply every two hours or after swimming. Wear a brimmed hat, sunglasses, and a long-sleeve, tightly woven shirt; prioritize shade during midday. Drink on a schedule, not by thirst alone, and include electrolytes during long efforts. Break early and often; treat nausea, cramps, or lightheadedness as stop signs, not speed bumps. Cool first, move second: shade, wet skin, fan, and seek care quickly if confusion or high fever appears.
When to seek help, and what clinic support looks like on the island
If you are unsure, ask. A short visit to doctor koh yao can prevent days of pain. We see burns and heat issues daily in high season. We carry dressings for blisters that do not stick, creams without irritant fragrances, oral rehydration salts, and the judgment that comes from treating these same problems across years and hundreds of cases. If something feels off, if a child seems unusually sleepy after a day in the sun, if a friend stops making sense, or if you cannot control pain with basic steps, let us take a look.
The island has limitations. Ferries and weather can delay transfers to larger hospitals. That is another reason to act early. We coordinate with boat operators and resort managers to move people fast when needed. Cooling and hydration begin here. We stabilize what we can, and we do not wait for perfect conditions to start the basics that save brains and kidneys.
Final thoughts from a shaded porch
I write this late afternoon with the sound of long-tail engines fading and the sea turning from silver to blue. The same sun that powers a perfect day can overrun you if you pretend it gives unlimited grace. Treat it with respect, and it will reward you. Skipping a midday swim, wearing doctor koh yao a long-sleeve shirt, or ducking into the shade for ten minutes is not defeat. It is wisdom earned by other people’s mistakes, and sometimes my own.
If you are reading this before your trip, pack the hat you think looks too big, bring the sunscreen you will actually use, and build in shade to your plans. If you are reading this after a rough day with a red back and a pounding head, start cooling, hydrate, and rest. If anything feels bigger than you can handle alone, walk into clinic koh yao. We will meet you with water, gauze that does not stick, and the unglamorous, proven steps that return you to the beach with fewer mistakes to repeat.
Takecare Medical Clinic Doctor Koh Yao
Address: •, 84 ม2 ต.เกาะยาวใหญ่ อ • เกาะยาว พังงา 82160 84 ม2 ต.เกาะยาวใหญ่ อ, Ko Yao District, Phang Nga 82160, Thailand
Phone: +66817189081