Why do doctors tell you not to cross your legs?

September 21, 2025 •

4 min read

A study found that sitting with your legs crossed for more than three hours per day can cause shoulder inclination and lateral pelvic tilt. It is this kind of postural stress that explains why doctors tell you not to cross your legs, often pointing to potential issues with circulation, spinal alignment, and nerve health.

Quick Summary

Doctors advise against crossing legs due to potential health concerns like temporary increases in blood pressure, poor circulation, nerve compression, and long-term postural issues that strain the back and hips. Regular, prolonged crossing of the legs disrupts the body's natural alignment and blood flow, prompting medical professionals to recommend better sitting habits.

Key Points

Blood Pressure Increase: Crossing your legs can cause a temporary but significant spike in blood pressure due to constricted veins, which is why doctors tell you not to during check-ups.
Postural Alignment: The habit rotates your pelvis, forcing your spine to compensate and leading to an imbalanced, unnatural posture that can cause back and neck pain.
Nerve Compression: Prolonged pressure on the peroneal nerve behind the knee can cause temporary numbness and tingling, and in rare cases, lead to more serious nerve issues.
Circulatory Issues: It impedes proper blood circulation in the lower extremities, which can exacerbate existing issues like varicose or spider veins over time.
How to Sit Better: The best way to sit is with both feet flat on the floor, knees at a 90-degree angle, and back supported to avoid strain and promote healthy alignment.

The Surprising Consequences of a Common Habit

Crossing your legs is a deeply ingrained habit for many people. It feels natural, comfortable, and for some, an act of politeness taught from a young age. However, health professionals often advise against this common posture, and for good reason. What may seem like a simple way to sit can, over time, place undue strain on your body. The core reasons doctors warn against this habit are linked to its impact on your circulation, musculoskeletal alignment, and nerve function. Understanding these underlying physiological effects is the first step toward adopting a healthier sitting posture.

The Immediate Impact on Blood Pressure and Circulation

One of the most widely cited reasons for avoiding crossed legs is its effect on your circulatory system. When you cross one leg over the other, particularly at the knee, you compress the veins in your lower leg. This compression forces the heart to work harder to pump blood back up from the legs, leading to a temporary but significant spike in blood pressure.

Measuring blood pressure: This is why nurses and doctors always instruct you to sit with both feet flat on the floor when your blood pressure is being measured. An inaccurate, high reading could lead to misdiagnosis or unnecessary medication.
Heart strain: For healthy individuals, this temporary spike is typically not a major concern. However, for those with pre-existing hypertension or cardiovascular issues, regularly stressing the heart in this way can have more serious implications over time.
Slowed blood flow: The restriction of blood flow can also lead to temporary numbness or tingling, commonly known as "pins and needles," due to the lack of oxygen reaching the nerves in the affected limb. While this is usually harmless and resolves quickly, it's a clear signal that the position is impeding normal circulation.

Postural Misalignment and Its Effects on Your Back

Beyond circulation, the way you sit has a profound impact on your body's musculoskeletal health. Habitually crossing your legs places your body in an imbalanced position, which can lead to significant postural problems.

The Role of Pelvic and Spinal Alignment

The pelvis serves as the foundation for your spine. When you cross your legs, your pelvis rotates and tilts to one side, pushing one hip higher than the other. To compensate for this uneven foundation, your spine and shoulders must shift to keep your head balanced over your center of gravity. This constant, asymmetrical stress can lead to:

Lower back pain: Uneven weight distribution puts more strain on the muscles and ligaments of your lower back, leading to chronic discomfort.
Sciatica: The pressure on the hips can also irritate or compress the sciatic nerve, which runs from the lower back down the legs, causing shooting pain, numbness, or weakness.
Overall postural changes: Over time, this repeated misalignment can lead to more serious spinal issues, such as scoliosis or a forward head posture, which can cause neck and shoulder pain.

Nerve Compression and Potential for Damage

Sitting with one leg pressed against the other can also lead to direct pressure on a specific nerve. The peroneal nerve runs near the surface of the outer knee and is susceptible to compression when the legs are crossed.

Temporary numbness: This compression is the most common reason for temporary numbness and a weakened ankle or foot, a sensation that typically subsides once the pressure is released.
Risk of peroneal nerve palsy: While rare, prolonged and consistent pressure on this nerve can lead to a more serious condition known as peroneal nerve palsy. This can cause a persistent weakness in the foot and leg muscles, potentially resulting in "foot drop".

How to Break the Habit and Sit Properly

Breaking the habit of crossing your legs requires conscious effort and awareness. The key is to adopt ergonomic sitting principles that support your body's natural alignment. Here are some actionable tips:

Maintain Proper Foot Position: Keep both feet flat on the floor, about shoulder-width apart. If your feet don't comfortably reach the floor, use a footrest.
Support Your Lower Back: Ensure your chair provides good lumbar support. A small cushion or rolled-up towel can help fill the curve of your lower back, preventing slouching.
Use Active Sitting Techniques: Avoid staying in any one position for too long. Change your posture frequently and get up to stretch or walk around for a few minutes every 30 minutes.
Practice Ankle-Crossing: If you feel the need to cross your legs, crossing them at the ankles is a much safer alternative that puts less strain on your hips and back.
Adjust Your Workstation: Ensure your desk and chair are at the correct height. Your elbows should be at a 90-degree angle, and your eyes should be level with the top of your computer screen.

Comparison: Crossed Legs vs. Proper Sitting


Feature	Crossed Legs	Proper Sitting Posture
Pelvis	Tilted and rotated	Neutral, level position
Spine	Misaligned, potentially scoliotic	Balanced in natural 'S' curve
Hips	Uneven, one higher than other	Level and supported
Circulation	Restricted, potential blood pooling	Unimpeded, healthy flow
Nerves	Risk of compression (e.g., peroneal)	Protected, no undue pressure
Blood Pressure	Temporary spike, especially at the knee	Stable, accurate readings

Conclusion: Prioritizing Health Over Habit

In the grand scheme of things, crossing your legs occasionally is unlikely to cause serious, irreversible damage. However, habitual, prolonged leg-crossing presents a number of risks that are simply not worth taking. The advice from doctors is not about shaming a polite social custom but about promoting long-term musculoskeletal and circulatory health. By understanding the potential for spinal misalignment, increased blood pressure, and nerve compression, you can consciously choose better sitting habits. For more information on maintaining good posture and its numerous health benefits, consult authoritative sources like the National Institutes of Health. Breaking the habit is a small change with significant benefits for your body's overall well-being, helping to prevent aches, pains, and more serious complications down the line.

Frequently Asked Questions

For most people, temporary numbness or tingling from crossing your legs is not permanent. However, very prolonged and habitual pressure on the peroneal nerve at the knee can, in rare cases, lead to a more serious condition known as peroneal nerve palsy.

Yes, crossing your ankles is a much better alternative. It avoids the significant pelvic rotation and pressure on the veins behind the knee that occurs when crossing at the knees, making it a safer posture.

While it can exacerbate existing circulatory issues, crossing your legs does not directly cause varicose veins. Genetic factors and age are the primary causes, but prolonged leg-crossing can add pressure that makes the condition worse over time.

Most experts recommend avoiding crossing your legs for more than 15-30 minutes at a time. The key is to not stay in any single position for an extended period. It is best to change your posture frequently and take breaks to stand and stretch.

When you cross your legs at the knee, you squeeze the veins, making it harder for blood to flow back to your heart. In response, your heart temporarily pumps harder to compensate, which elevates your blood pressure reading.

Yes. Since prolonged leg-crossing can lead to pelvic and spinal misalignment, correcting this habit and sitting with proper posture can help alleviate chronic lower back and hip pain.

The ideal posture involves sitting with both feet flat on the floor, knees bent at a 90-degree angle, and your back fully supported by your chair, using a lumbar support if necessary. Avoid slouching and take frequent breaks.