# Preventing DVT on Long Flights: Blood Clot Risks and Precautions URL: https://emptvl.vercel.app/travel-guides/preventing-dvt-on-long-flights Publisher: Empyrean Travel (https://emptvl.vercel.app/) Last reviewed: 2026-10-19 Preventing DVT on long flights: who faces higher blood clot risk, in-flight habits that help, when to ask about compression stockings and warning signs. **Quick answer:** Long flights raise the risk of deep vein thrombosis, a blood clot usually in the leg, mainly for travelers with other risk factors. The CDC’s core advice is to move: walk the aisle every couple of hours when it’s safe and flex your calves while seated. If you have added risk, ask a clinician about compression stockings or medication before you fly. - Higher risk: Trips longer than about 4 hours - Best habit: Walk and flex your calves regularly - Aspirin: Not recommended by CDC for travel clots - Get help now: Sudden breathlessness or chest pain ## What is DVT, and why do long flights raise the risk? Deep vein thrombosis is a blood clot in a deep vein, usually in the leg. Sitting still for hours lets blood pool in the lower legs, which makes clots more likely. The danger is that part of a clot can break off and travel to the lungs, causing a pulmonary embolism. The CDC notes that any trip longer than about four hours, by plane, car, bus or train, can raise the risk, though the absolute risk is small for most healthy travelers. The longer the journey, and the more risk factors you have, the more these precautions matter. ## Who is at higher risk of blood clots when traveling? The CDC lists several factors that raise risk, and risk climbs when you have more than one. - A previous blood clot, a family history of clots or a known clotting disorder - Recent surgery, hospitalization or injury, including a leg in a cast - Estrogen-containing birth control or hormone therapy - Current or recent pregnancy - Older age and obesity - Cancer or cancer treatment ## How can you lower your risk during a long flight? Movement is the CDC’s core advice. Choose an aisle seat so you can get up easily, and walk around every couple of hours when the seat belt sign is off. While seated, raise and lower your heels and toes, and tighten and release your leg muscles. Wear loose, comfortable clothing and stay hydrated. A lie-flat seat makes it easier to change position, but it doesn’t replace getting up; our guides to seat selection and long-haul flight tips cover comfort more broadly. If you take a sleep aid, ask your clinician first, since deep sleep in one position for many hours means less movement. ## Should you wear compression stockings or take medication? That’s a decision for you and a clinician, based on your risk factors. For travelers with added risk, a doctor may recommend properly fitted graduated compression stockings or, for higher-risk travelers, medication before departure. Don’t self-prescribe. The CDC says taking aspirin to prevent blood clots when traveling isn’t recommended. If you’ve had a clot before or recently had surgery, discuss your travel plans well before you book. ## What are the warning signs after you land? Clots don’t always cause symptoms during the flight, so stay alert in the days after a long trip. Signs of DVT include swelling, pain or tenderness, warmth, and redness or discoloration, usually in one leg. About half of people with DVT have no symptoms at all. Signs of a pulmonary embolism include difficulty breathing, a fast or irregular heartbeat, chest pain that worsens with a deep breath or cough, coughing up blood, and lightheadedness or fainting. Seek medical care immediately; abroad, our guide to emergencies abroad explains who to call. ## Can itinerary planning reduce long stretches of sitting? Yes. On very long journeys, breaking the trip with a night in a hub city gives your body a real break and helps with jet lag too. Some airlines let you add a stop for no extra airfare; see stopover programs. Booking flights with reasonable connections, rather than back-to-back ultra-long sectors, is another easy win. ## Frequently asked questions **Q: How long does a flight have to be to cause DVT?** A: There’s no exact cutoff, but the CDC notes that travel lasting more than about four hours can raise the risk of blood clots. The longer the journey, the greater the risk, especially for travelers with other risk factors. For most healthy travelers the absolute risk is small, and regular movement during the flight helps reduce it further. **Q: Do compression socks prevent blood clots on flights?** A: Properly fitted graduated compression stockings may help travelers at higher risk, and a doctor may recommend them if you have risk factors such as a previous clot or recent surgery. Ask a clinician whether they’re right for you and what level of compression to use. For most travelers, regular walking and calf exercises are the core precautions. **Q: Should I take aspirin before a long flight?** A: Not for clot prevention unless a clinician tells you to. The CDC says taking aspirin to prevent blood clots when traveling isn’t recommended. If you have risk factors, talk to your doctor before the trip; they may recommend compression stockings or, for higher-risk travelers, a different medicine. Don’t start or stop any medication on your own. **Q: Is an aisle seat better for preventing blood clots?** A: It helps, because you can get up and walk without disturbing anyone, which makes you more likely to move regularly. The CDC suggests an aisle seat for that reason. Whatever seat you choose, get up every couple of hours when it’s safe, and do heel raises, toe raises and leg muscle squeezes while seated. **Q: What should I do if my leg swells after a flight?** A: Some mild ankle swelling after a long flight is common and usually fades with walking. But swelling in one leg with pain, tenderness, warmth or redness can signal a blood clot, so contact a clinician promptly. If you also have chest pain, shortness of breath or a racing heartbeat, seek emergency care immediately. ## Sources - [CDC: Blood clots during travel](https://wwwnc.cdc.gov/travel/page/dvt) - [Centers for Disease Control and Prevention](https://www.cdc.gov/)