A long road trip means hours in the same seat.
Most people notice stiff knees or a sore back by the end of the day.
Fewer people think about what all that sitting does to the blood in their legs.
Sitting still for a long time can raise the chance of a blood clot deep in a leg vein.
Doctors call it deep vein thrombosis, or DVT.
It can be serious when it happens, but simple habits lower the risk for most travelers.
This guide explains the risk in plain terms, using information from the National Institutes of Health.
It covers who should be most careful, habits that help and the warning signs to know.
It is general information, not medical advice.
If you have a health condition, talk with your healthcare provider before a long trip.
What deep vein thrombosis is
According to MedlinePlus, DVT is a blood clot that forms in a vein deep in the body.
Most of these clots form in the lower leg or thigh.
The bigger danger comes if the clot breaks loose.
It can travel to the lungs and cause a serious problem there.
That is called a pulmonary embolism, and it can be life-threatening.
The National Heart, Lung, and Blood Institute groups both problems under one name.
It calls them venous thromboembolism, or VTE.
Why long hours in the car matter
The NHLBI explains that being still slows blood flow through the veins in your arms and legs.
Slower blood flow makes it easier for a clot to form.
MedlinePlus also notes that sitting still for a long time can make you more likely to get DVT.
The NHLBI says long flights of more than 4 hours more than double the likelihood of VTE.
A car is not an airplane, but a full day of driving can mean just as many hours of sitting.
The good news is that a road trip gives you more control than a flight.
You choose when to stop, where to stretch and how long to rest.
Who should be most careful
The NHLBI notes that most of the time, more than one risk factor is involved.
The more risk factors you have, the greater the chance of VTE.
Factors it lists include:
- Recent surgery, since the chance is highest in the first 3 months afterward.
- A blood clotting disorder or a history of blood clots.
- Cancer and some cancer treatments.
- Heart conditions such as heart failure, and high blood pressure.
- Diabetes, kidney disease and obesity.
- A family history of VTE.
- Older age, since the chance nearly doubles every 10 years after age 40.
The NHLBI also notes that before menopause, women are more likely than men to get VTE.
After menopause, the likelihood is higher in men.
If any of these factors apply to you, talk with your healthcare provider before a long trip.
Ask whether you need a specific plan for the drive.
Plan stops every one to two hours
The most useful habit is easy to build into a road trip.
For travelers, the NHLBI advises standing up and walking around every 1 to 2 hours, if possible.
MedlinePlus gives similar advice for long car trips: take a break, walk or stretch your legs.
Plan your route with that rhythm in mind.
- Mark rest areas, gas stations and parks along the way before you leave.
- Pair stops with things you need anyway, such as fuel, food or restrooms.
- Walk for a few minutes at each stop instead of sitting in the car.
- Use the break to switch drivers if someone else can drive.
Regular breaks also help with fatigue.
Our guide to drowsy driving on long road trips explains why rest matters for the driver.
Make the stops part of the trip
Frequent breaks are easier when they feel like part of the adventure.
Look for short walks near your route, such as a scenic overlook or a small town main street.
A ten-minute walk around a rest area also counts.
Kids often enjoy a quick game at each stop, like a race to a tree and back.
Older travelers may prefer a slow walk and a stretch beside the car.
The goal is the same for everyone: get up and move your legs.
Build the stops into your arrival time so nobody feels rushed.
Our guide on estimating gas costs can help you plan fuel stops that double as breaks.
Simple moves for passengers
Passengers can do more between stops than the driver can.
The NHLBI lists several habits that help while you are seated.
- Flex and extend your knees and ankles often.
- Change positions often while seated.
- Avoid crossing your legs, if possible.
- Wear loose-fitting clothing.
A simple ankle routine works well in the back seat.
Point your toes forward, then pull them back toward you, and repeat several times.
Then roll your ankles in slow circles in both directions.
Set a reminder on your phone if you tend to forget.
What the driver can do safely
The driver's job is to drive, so exercises should never take attention from the road.
Save stretching and walking for stops, when the car is parked.
A few habits still help behind the wheel.
- Adjust the seat so your legs are comfortable and not cramped.
- Wear loose clothing that does not squeeze your legs or waist.
- Keep a steady plan of stops instead of pushing through long stretches.
- Share the driving when you can, so you also get time as a passenger.
Drink water and skip alcohol
MedlinePlus advises drinking plenty of liquids on a long car or plane trip.
Many travelers skip water to avoid stopping.
On a road trip, more stops are actually a good thing.
Keep a refillable bottle within reach of every passenger.
The NHLBI also advises avoiding alcohol during travel, since it may lower your ability to move around.
The driver should never drink alcohol before or during a drive.
Passengers are better off skipping it on long travel days too.
Compression stockings
The NHLBI includes compression stockings among its tips for lowering the chance of VTE during travel.
These stockings apply gentle pressure, with more pressure around the ankles and feet.
They come in different strengths and sizes.
Ask your healthcare provider or pharmacist which type and fit are right for you.
This matters most if you have risk factors or a history of clots.
Warning signs to know
The NHLBI says to call your healthcare provider right away if you think you may have symptoms of VTE.
Signs of a clot in the leg can include:
- Swelling in the leg.
- Pain or tenderness, especially when the area is touched.
- Warmth over the vein.
- Redness of the skin.
Signs that a clot may have reached the lungs include shortness of breath and pain when breathing.
Those signs need emergency care right away, so call 911.
The NHLBI also notes that VTE sometimes causes no symptoms until serious complications develop.
That is one more reason to focus on prevention.
Do not wait until you get home if symptoms appear during the trip.
Find the nearest clinic or hospital along your route.
Long drives after surgery or an injury
Some road trips happen soon after a medical procedure.
A family might drive home after surgery in another city, or travel to recover with relatives.
The NHLBI notes that the chance of VTE is highest in the first 3 months after surgery.
Moving less than usual, such as while wearing a cast, also slows blood flow.
In that case, ask the medical team for a travel plan before the drive.
They may suggest specific medicines, stockings or a schedule for breaks.
A road trip circulation checklist
- Talk with your provider first if you have risk factors.
- Plan a stop every 1 to 2 hours and walk for a few minutes.
- Passengers flex ankles and knees often and change positions.
- Avoid crossing your legs for long periods.
- Wear loose, comfortable clothing.
- Keep water within reach and skip alcohol on travel days.
- Know the warning signs in the legs and in breathing.
For the rest of your preparation, see our pre-trip car check.
The bottom line
Long hours in a seat slow blood flow in your legs.
Regular stops, simple leg movement and plenty of water help lower the risk.
If you have risk factors, plan your trip with your healthcare provider.
Know the warning signs, and get care quickly if they appear.
Sources and Further Reading
- National Heart, Lung, and Blood Institute: Preventing Blood Clots — supports the travel tips (walking every 1 to 2 hours, loose clothing, ankle and knee movement, changing positions, compression stockings, avoiding alcohol), the long-flight risk and the higher risk after surgery.
- National Heart, Lung, and Blood Institute: VTE Causes and Risk Factors — supports how being still slows blood flow and the list of risk factors, including age, sex and family history.
- National Heart, Lung, and Blood Institute: VTE Symptoms — supports the leg and breathing warning signs and the advice to call a provider right away.
- MedlinePlus (National Library of Medicine): Deep Vein Thrombosis — supports the definition of DVT, the risk from sitting still, common symptoms and the advice for long car trips.