To stay healthy on a long-haul flight, drink plenty of water, go easy on alcohol and caffeine, get up and move around about every hour, wear loose clothing and switch to your destination's time as soon as you can. Long flights are safe for most people, but sitting still for hours raises the chance of a blood clot, the cabin air is dry and crossing time zones brings jet lag. Below you'll find what to do before, during and after the flight, with advice from the NHS, the UK's official travel health service and airline medical teams.
Before Your Flight
Rest and shift your sleep
Get plenty of rest before you travel. The NHS suggests you can start going to bed and getting up earlier or later than usual, closer to the time zone you're flying to (NHS). Emirates' health team adds that too little sleep before the journey can make jet lag worse (Emirates).
Check your health and your medicines
If you're pregnant or have a health condition, book an appointment with your doctor well before the trip. TravelHealthPro, the UK's official travel health service, also advises an appointment ideally four to six weeks before travel if you need vaccines or malaria tablets (TravelHealthPro).
- Carry your medicines in their original pharmacy packets, with copies of your prescriptions and enough for delays.
- Check the rules of every country you visit or pass through for the medicines you take.
- Get travel insurance that covers your health, and declare any medical conditions.
Book the flight that suits you
A non-stop flight gets the trip over with in one go, while a layover gives you a chance to stretch your legs and break the time in the seat. Our guide to direct vs layover flights weighs up both. When you choose a seat, think about how often you'll want to get up: an aisle seat makes walking around easier.
Sort your phone before you leave
Set up your mobile data at home, not in the arrivals hall. With an eSIM installed before you fly, you can message family that you've landed, open maps and call a ride straight away, which takes a lot of stress out of arriving tired. Follow our eSIM installation guide and check your phone in the list of eSIM compatible devices.
During the Flight
Drink water and limit alcohol and caffeine
Drink plenty of water during the flight. The NHS says too much caffeine or alcohol can make jet lag worse (NHS), and it lists dehydration as one of the things that make a blood clot more likely (NHS). Emirates notes that alcohol, coffee and tea act as diuretics, so it recommends water and juices instead (Emirates).
Get up and move around
Don't sit still for long periods. The NHS advice is to get up and move around every hour or so (NHS). When you can't walk, TravelHealthPro recommends regularly flexing and extending your ankles to keep blood flowing from your lower legs (TravelHealthPro). Emirates suggests these in-seat exercises every few hours:
- Feet circling: circle your feet at the ankles, 20 times each foot.
- Foot presses: lift your heels and press your toes into the floor, then lift your toes and press your heels down, 10 times for each foot.
- Knee presses: press your knees and thighs together and tighten your buttock muscles, hold for 5 and repeat 5 times.
- Shoulder circles: with your arms at your sides, circle your shoulders forwards 10 times, then backwards 10 times.
Put your bag in the overhead bin rather than under the seat in front of you. Both TravelHealthPro and Emirates point out that luggage under the seat restricts how much you can move your legs.
Dress for comfort
Wear loose, comfortable clothing. TravelHealthPro advises against tight clothing around your waist or legs on long journeys. Layers help too, so you can adjust as the cabin gets warmer or cooler.
Look after your skin and eyes
Cabin air has low humidity, which can dry your skin, nose, throat and eyes. To reduce this, Emirates recommends avoiding alcohol and caffeine, swapping contact lenses for glasses during the flight and using a moisturiser (Emirates).
Eat lightly and sleep at the right time
Digestion slows down when you're inactive, so lighter meals make for a more comfortable flight. Try to sleep if it's night time at your destination, and use an eye mask and earplugs if they help (NHS).
Ask about compression socks if you're at higher risk
TravelHealthPro says travellers at increased risk of a blood clot should consider properly fitted below-knee graduated compression socks, giving 15 to 30 mmHg of pressure at the ankle. Pregnant travellers on flights over 4 hours should have them fitted. They need to be measured correctly, because badly fitted socks can be uncomfortable and even affect circulation. Ask your doctor or pharmacist before you buy. Taking aspirin to prevent clots during travel is not recommended (TravelHealthPro).
Blood Clots on Long Flights: Know the Risk
A deep vein thrombosis (DVT) is a blood clot in a vein, usually in the leg. For most travellers the risk is low. TravelHealthPro, citing World Health Organization research, estimates it at about 1 in 6,000 for a healthy person on a flight of more than 4 hours. The risk grows with longer journeys and with several flights in a short time (TravelHealthPro).
Who is more at risk?
The NHS lists factors that make DVT more likely, including being over 60, living with obesity, smoking, having had DVT before, taking HRT or contraception that contains oestrogen, cancer or heart failure, being pregnant or having had a baby in the previous 6 weeks, recent surgery and being dehydrated (NHS). If any of these apply to you, talk to your doctor before a long flight.
Symptoms to watch for
Signs of DVT include throbbing pain and swelling in one leg, usually in the calf or thigh, red or darkened skin around the painful area and swollen veins. Get medical help quickly if you notice them. If you also feel short of breath or have chest pain, call your local emergency number straight away, because a clot that travels to the lungs can be life-threatening (NHS).
After You Land
Switch to local time
Jet lag usually improves within a few days as your body adjusts. The NHS recommends you change your sleep schedule to the new time zone as quickly as possible, set an alarm so you don't oversleep in the morning, go outside during the day because natural light helps your body clock adjust, and avoid sleeping during the day (NHS).
Emirates says your body resets at about one day for every time zone you cross, and that most people find flying west easier than flying east. Eat at local meal times and avoid caffeine in the hours before bed (Emirates). On a short trip of 2 to 3 days, the NHS says you could keep your home eating and sleeping times instead.
What about melatonin and sleeping tablets?
The NHS says medicines are not usually needed for jet lag. Melatonin tablets are not recommended on the NHS for jet lag because there's not enough evidence that they work, and sleeping tablets can be addictive, so they're only for short-term use if symptoms are severe. Speak to a doctor before you take either. For more ideas, read our guide on what actually works to minimise jet lag.
Keep moving and keep drinking water
A walk outside on your first day gets you moving after hours in a seat and gives you daylight at the same time. Keep drinking water, especially if you're arriving somewhere hot. Feeling worn out by travel? Read how to deal with travel burnout, with signs, rest and recovery.
Stay Connected When You Land
During the flight, follow the crew's instructions on phone use and airplane mode. Once you land, an eSIM installed at home connects to a local network, so you can tell family you've arrived, open your hotel booking and get directions without hunting for Wi-Fi. Our tips on how to stay connected while travelling cover the other options.
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FAQs
Are long-haul flights bad for your health?
For most healthy people, no. The main risks are a small chance of a blood clot from sitting still, dry cabin air and jet lag. Moving around, drinking water and adjusting to local time help with all three.
How often should you get up on a long flight?
The NHS advises getting up and moving around every hour or so. When you can't, flex and extend your ankles in your seat.
Should everyone wear compression socks on a long flight?
TravelHealthPro recommends them for travellers at increased risk of a blood clot, and for pregnant travellers on flights over 4 hours. They must be properly fitted, so ask your doctor or pharmacist first.
Is it OK to drink alcohol on a long flight?
Go easy. The NHS says too much alcohol or caffeine can make jet lag worse and advises avoiding alcohol on long journeys to lower the risk of DVT.
Why does my skin feel dry on a plane?
Cabin air has low humidity. Drink water, use a moisturiser and wear glasses instead of contact lenses if your eyes get dry.
How long does jet lag last?
The NHS says it usually improves within a few days. Emirates estimates your body resets at about one day per time zone crossed.
What's the best way to stay connected after an international flight?
Install an eSIM for your destination at home before you fly. It connects when you land, so you don't depend on airport Wi-Fi or expensive roaming.
