Dengue Fever in Thailand: Prevention & What to Do (2026)

The real talk: Dengue fever is the most common illness that affects backpackers in Thailand. Thousands of travelers get it every year. The good news? It's not like malaria — there's no mysterious incurable disease. The better news? You can prevent it almost entirely with proper precautions. This guide breaks down the risks, how to stay safe, and exactly what to do if you do get infected.

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What is Dengue Fever?

Simple explanation: A virus spread by mosquitoes. Not life-threatening for most people, but very unpleasant.

How it spreads:

• Aedes mosquito carries the virus
• Mosquito bites you → virus enters your bloodstream
• 3-14 days later: Symptoms appear

Why it's called "Breakbone Fever": The joint/muscle pain is SEVERE. People describe it like your bones are breaking. You'll understand when (if) you get it.

Key fact: There is NO vaccine for travelers. Dengvaxia vaccine exists, but it's only for people who've already had dengue (to prevent severe reinfection). Travel health clinics won't give it to you. Prevention is everything.

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Dengue Risk in Thailand: Where and When

By Region

Low Risk (City Centers):

• Bangkok city center (BTS/MRT areas)
• Chiang Mai Old City
• Phuket City
• Risk: Minimal if you stay in air-conditioned spaces

Moderate Risk (Most Tourist Areas):

• Bangkok overall (outskirts have more mosquitoes)
• Chiang Mai (especially suburbs)
• Koh Samui, Koh Tao
• Krabi, Railay
• Risk: Moderate. Get bitten once every 2-3 weeks during peak season

Higher Risk (Wet Season Areas):

• Andaman Islands (Phuket, Krabi, Phang Nga) May-October
• Gulf Islands (Koh Samui, Koh Phangan) June-October
• Northern Thailand (Chiang Mai, Chiang Rai) June-October
• Risk: Much higher during monsoon

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By Season

Peak Dengue Season (June-October):

• Rainy season = standing water = mosquitoes breeding
• Bangkok: June-September peak
• Chiang Mai: July-October
• Islands: May-October
• Expect higher transmission, especially July-September

Lower Season (November-May):

• Still present but less common
• Dry season = fewer breeding grounds
• Bangkok has year-round dengue (hot + humid always)

Peak danger window: Mid-June to mid-September. If you're visiting then, take extra precautions.

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Prevention: How to NOT Get Dengue

The #1 Prevention: DEET 50%

Why DEET works:

• Only repellent proven effective against Aedes mosquitoes
• 50%+ concentration recommended
• Lasts 4-8 hours depending on brand
• Available everywhere in Thailand (7-Eleven, pharmacies, online)

How to use it:

• Apply to exposed skin (arms, legs, neck, behind ears)
• Reapply every 4 hours or after swimming
• Can use daily for weeks with no safety issues
• Works better than any other repellent (Picaridin/IR3535 are weaker)

Best brands in Thailand:

• Off! Insect Repellent (spray or lotion)
• Autan (popular in Europe)
• Raid Max
• Generic DEET lotion from pharmacy

Cost: 100-200 baht per bottle. Cheap insurance.

Reality check: "Natural" repellents (lemongrass oil, citronella) are mostly useless against dengue-carrying mosquitoes. Spend the 150 baht on real DEET.

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Prevention #2: Protective Clothing

The Aedes mosquito bites during the day (unlike other mosquitoes that bite at night).

Peak danger times:

• Early morning (5am-9am)
• Late afternoon (3pm-6pm)

How to protect:

• Wear long sleeves + long pants during these hours
• Light colors (mosquitoes see dark colors better)
• Loose fit (mosquitoes can bite through tight fabric)
• Close-toed shoes

Problem: Thailand is hot. Wearing long sleeves in 35°C heat sucks.

Solution:

• Lightweight linen long sleeves (breathable)
• Thin cotton pants
• Stay in air-conditioned spaces during peak hours
• Combine with DEET on exposed areas (face, neck, hands)

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Prevention #3: Stay in Places with Good Screens/AC

Aedes mosquitoes are indoor/outdoor.

Accommodation tips:

• Choose hostel/hotel with window screens (not just glass)
• Air-conditioned rooms are best (mosquitoes avoid AC)
• Avoid rooms with large gaps under doors
• Check for standing water near accommodation (breeding grounds)

Reality check: Most tourist accommodations in cities are fine. Guesthouses in remote areas might not have screens.

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Prevention #4: Avoid Standing Water

Aedes breeds in small amounts of water:

• Plant pots
• Flower vases
• Puddles in gardens
• Clogged gutters
• Old tires, discarded bottles

What you can do:

• Don't let water pool in your room
• Empty any containers
• Keep gutters clear if you're in a longer-term place
• This helps the community prevent dengue for everyone

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Dengue Symptoms: How to Recognize It

Timeline: Symptoms appear 3-14 days after mosquito bite

Classic dengue fever symptoms:

• Sudden high fever (39-40°C / 102-104°F)
• Severe headache (often behind the eyes)
• Pain behind the eyes (this is classic dengue)
• Severe muscle and joint pain ("breakbone fever" — it really hurts)
• Rash (often appears 3-4 days in, looks like measles)
• Nausea/vomiting
• Fatigue (extreme exhaustion)

What it feels like: Imagine the worst flu ever combined with terrible body aches. You'll lie in bed unable to move. The pain is the worst part.

How long it lasts:

• Acute phase: 3-7 days
• Recovery phase: Fatigue can last 2+ weeks
• Most people recover fully within 1-2 weeks

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Important: Dengue Variations

First dengue infection: Unpleasant but usually not dangerous

Second dengue infection (different strain): More serious

• Higher risk of severe dengue hemorrhagic fever
• Can involve internal bleeding
• Needs hospital monitoring

This is why dengue vaccine (Dengvaxia) exists — but only for people who've had dengue before.

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What to Do If You Get Dengue

Step 1: Confirm You Have Dengue

• Go to hospital/clinic when fever starts (within 24 hours ideally)
• Blood test (NS1 antigen test) confirms dengue in first 3-5 days
• Takes 1-2 hours for results
• Tell doctor: "I think I have dengue"

Step 2: Self-Care for Mild Dengue (Most Cases)

Fluids (most important):

• Drink water constantly (2-3 liters daily minimum)
• Oral rehydration salts (ORS) — buy at any pharmacy
• Coconut water (natural electrolytes)
• Soup (broth adds salt + hydration)
• Avoid alcohol completely

Medication:

• Paracetamol/Acetaminophen ONLY for fever and pain
• NEVER ibuprofen, aspirin, or NSAIDs — these increase bleeding risk with dengue
• 500mg every 4-6 hours, max 2000mg/day

Rest:

• Stay in bed, minimize movement
• Cancel activities for 1 week minimum
• Exhaustion is real — listen to your body

Food:

• Light, easily digestible food
• Soup, rice, crackers
• Avoid heavy/spicy food
• Appetite will be low — eat when you can

Step 3: When to Go to Hospital

Go immediately if:

• Fever suddenly drops (warning sign of dengue hemorrhagic fever)
• Severe vomiting (can't keep anything down for 4+ hours)
• Severe abdominal pain
• Bleeding (nosebleed, blood in vomit/stool)
• Persistent headache with confusion
• Respiratory difficulty
• Very low energy (inability to stay conscious)

Warning signs: Dengue hemorrhagic fever is rare but serious. Modern hospital care has ~1% mortality. Go to hospital if anything feels wrong.

Step 4: Hospital Treatment (If Needed)

What happens:

• Blood test to confirm dengue + severity
• IV fluids (to combat dehydration)
• Observation (usually 3-7 days)
• Regular blood work to monitor platelet count
• Monitoring for hemorrhagic signs

Cost in Thailand:

• Private hospital: 15,000-40,000 baht (3-7 days)
• Government hospital: 5,000-10,000 baht
• Travel insurance covers this

Reality: Most dengue cases don't need hospital. Just fluids and rest at home.

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Recovery & Returning to Normal

Week 1 (Acute phase):

• Severe fever, aches
• Mostly in bed
• Pain medication + fluids
• Usually improves day 4-5

Week 2 (Recovery phase):

• Fever is gone
• Still extremely tired
• Rash may appear
• Can start moving around slowly

Week 3+:

• Fatigue lingers
• Can do light activities
• Full energy returns over 2-4 weeks
• Some people feel weak for longer

Important: Don't rush recovery. Dengue exhaustion is extreme. Rest properly or you'll relapse.

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Dengue vs. Other Tropical Illnesses

Dengue vs. Malaria:

• Malaria: Rare in tourists, prevented with prophylaxis pills
• Dengue: Much more common, no vaccine or pills, only prevention

Dengue vs. Typhoid:

• Typhoid: Also high fever but lasts 3+ weeks untreated
• Dengue: Usually 5-7 days with good care

Dengue vs. Food Poisoning:

• Food poisoning: Stomach issues primarily
• Dengue: Body/joint pain + fever

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Is There a Dengue Vaccine?

Dengvaxia vaccine exists, but:

• Only approved for people with prior dengue infection
• Only for adults 18-45 years old
• Designed to prevent severe reinfection
• NOT available for travelers

Why not? It increases risk of severe dengue if you get dengue when you have no prior immunity. So they only give it to people who've already had it once.

Bottom line: There's no traveler vaccine. Prevention only.

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Real-World Scenario: Getting Dengue

Day 1: Feel fine, go trekking, get bitten by mosquito (don't realize it)

Days 2-3: Feel slightly off, minor fever

Day 4: FEVER 39°C, headache, body aches, go to hospital

Day 4 evening: Blood test confirms dengue (NS1 positive)

Days 5-7: In bed with fever, on paracetamol + fluids, can't move

Day 8: Fever drops, start feeling better, rash appears

Days 9-14: Recover, still tired, light activities only

Weeks 3-4: Back to normal

Total hospital cost: If admitted, 20,000B (~$550). Insurance covers.

Time lost: 1-2 weeks of travel

This is why prevention matters. A bottle of DEET costs 150 baht. Much better deal.

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Prevention Checklist

Before traveling to Thailand (June-September):

☐ Buy DEET 50%+ insect repellent ☐ Buy lightweight long sleeves + pants ☐ Book accommodation with screens or A/C ☐ Get travel insurance (covers dengue hospitalization) ☐ Know these symptoms

Daily during dengue season:

☐ Apply DEET to exposed skin (morning + afternoon) ☐ Reapply after swimming or every 4 hours ☐ Wear long sleeves during 5-9am and 3-6pm ☐ Check accommodation for standing water ☐ Stay indoors during peak mosquito hours if possible

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FAQ: Dengue Fever

If I get dengue once, am I immune? You're immune to that strain, but there are 4 dengue strains. You could theoretically get each one once. Second infection is more serious.

How many people get dengue in Thailand? ~100,000+ cases annually in Thailand. Thousands are tourists. It's common but not universal.

Do I need a dengue vaccine? Not available for travelers. Prevention only. Get good DEET.

Is dengue deadly? Dengue hemorrhagic fever (severe form) can be fatal, but it's rare and treatable in hospitals. Death rate under 1% with good care.

Can I get dengue twice? Yes, from different strains. But risk of getting all 4 strains during tourism is low.

Will I definitely get dengue in Thailand? No. Thousands of tourists prevent it with DEET and proper clothing. It's possible to visit without getting it.

What if I get dengue at the end of my trip? You might be flying home sick. Travel insurance helps. Fly home and recover there if possible. You're contagious for ~5 days (don't want to spread it).

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Final Recommendation

Prevention takes 5 minutes per day:

1. Buy DEET (150B at 7-Eleven) — apply every 4 hours
2. Wear long clothes during peak hours (5-9am, 3-6pm)
3. Stay indoors during peak hours if possible (use air-con)
4. Choose good accommodation (screens, A/C)

This combo = 90%+ protection.

Dengue is uncomfortable but not dangerous if caught early and treated well. Prevention is way easier than recovery. Spend 30 minutes setting up, then forget about it.

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Getting dengue in Thailand? Don't panic. Go to hospital, get fluids, rest, and you'll be fine in 1-2 weeks. Have dengue prevention questions? Drop them in comments.