Sitting still for long periods during travel may increase the risk of developing blood clots. Untreated blood clots may lead to serious and even life threatening complications, like pulmonary embolism.

Blood clots form when platelets in the blood clump together and create a plug in a vein or artery. Clots typically happen in the legs, thighs, pelvis, or arms. They may hinder blood flow in the affected area or dislodge and travel to the lungs, causing a life threatening condition called pulmonary embolism.

Blood clots can occur during travel, so it’s important to understand the symptoms and what factors may put you at higher risk.

Learn more about deep vein thrombosis (DVT).

When a body isn’t in motion, blood flow through the arms and legs slows down. This may lead to blood clots, also called venous thromboembolism.

During travel, people sit for extended periods, whether in a car, bus, plane, train, or another vehicle. The potential to develop blood clots increases when a person sits still for more than 4 hours at a time.

Other factors that may contribute to blood clots during travel include pressure on the back of the knee joint from sitting in a seat and air pressure changes in an airplane.

Taking a walk break every 2 to 3 hours may prevent blood clots during travel. Stop at rest stops or other places, like stores or parks, where you can get out and stretch.

If you’re on a flight or train and can’t get up, try:

  • alternating raising and lowering your heels while keeping your toes on the floor and raising and lowering your toes while keeping your heels on the floor
  • tightening and releasing your leg muscles
  • pulling your knees toward your chest and holding (with your arms around your lower legs) for a total of 15 seconds, repeating this 10 times
  • wearing loose clothing
  • taking naps instead of long periods of sleep or taking sleeping pills
  • avoiding alcohol and staying well hydrated

If you have additional risk factors, your doctor may suggest wearing compression socks or stockings or taking medications. The Centers for Disease Control and Prevention (CDC) doesn’t recommend taking baby aspirin unless your doctor suggests it.

You may not notice any symptoms until the blood clot becomes serious. In fact, half of people with DVT don’t experience any symptoms.

Watch for:

  • swelling in the affected leg or arm
  • pain or cramping that doesn’t have an obvious cause
  • warmth in the area when touched
  • discoloration or redness of the surrounding skin

Seek immediate medical attention if you experience symptoms of pulmonary embolism, including:

Again, travel itself is a risk factor for blood clots due to sitting still for long periods and blood pooling in the legs. People flying for 8 to 10 hours or more are at the highest risk.

Your risk may further increase if you have any of the following:

  • an injury to a vein
  • a history of blood clots
  • a family history of blood clots
  • surgery or hospitalization within the past 3 months
  • pregnancy
  • an age over 60 years
  • a high body mass index (BMI)
  • current cancer treatment or chemotherapy
  • current birth control or hormone replacement therapy with estrogen
  • other health conditions, like inflammatory bowel disease or congestive heart failure

If you have symptoms of a blood clot, head to an urgent care center or emergency room. Your hotel or travel agency may have suggestions on where to go, or you can locate a nearby hospital with a quick online search.

If you’re traveling internationally, contact the nearest embassy or consulate to locate medical care and assistance. You can also check out the International Society of Travel Medicine’s clinic directory.

Some clots may go away on their own. Regardless, it’s important to contact a doctor.

Treatment involves taking blood-thinning medications, like warfarin, to break up the clot. Your doctor may also suggest wearing compression socks to help with pain and swelling. If the clot doesn’t go away, it may need surgical removal.

You may need to take blood thinners for weeks to months to resolve your clot and prevent new clots from forming.

Prompt treatment can help resolve the clot before it becomes serious or leads to pulmonary embolism.

That said, around one-third of people with DVT may develop another clot within 10 years, according to the CDC. And up to half of people may experience lingering symptoms, like swelling, pain, or skin discoloration.

Can you travel if you have a blood clot?

Experts recommend waiting 3 to 4 weeks to travel by plane if you’ve recently had a diagnosis of a blood clot. At the very minimum, you should finish your loading dose of blood-thinning medication before traveling.

Can you travel while on blood thinners?

You may travel while taking blood thinners. Follow all medication instructions from your doctor.

How long after flying are you at risk of a blood clot?

The risk of experiencing a blood clot increases with a flight that’s 4 hours or longer. As many as 1 in 4,600 people may experience a blood clot within a month of their flight.

Blood clots are a risk when traveling, but prevention measures are effective. Speak with your doctor before your trip if you have concerns about blood clots.

If you’re planning to take a particularly long flight or another journey without the opportunity for walk breaks, consider setting a timer to do seated leg exercises and stretching at least every 2 hours.