For most people the back pocket is a go-to place for their wallet, billfold or maybe even car keys. 

 Sitting on your wallet can be the cause of serious pain in your back, hip and even leg.

Not only does sitting with a wallet in your pocket pinch your sciatic nerve, it can also cause your pelvis and spine to position in a way that isn’t straight or natural. Think about how it would be to walk while only wearing one shoe. Sitting with a wallet on one side does the same thing to throw off your alignment. The bigger your wallet, the bigger the problem.

Sitting with your wallet or other items in the back pocket creates an uneven sitting surface. This creates an unlevelled pelvis and an imbalanced spine; which might cause lower back pain leading to compensation of the muscles supporting your spine.

The longer you choose to sit on an uneven surface the more likely you are to experience pain. This applies to the length of time you sit on an uneven surface . 

Individuals with underlying postural and spinal alignment issues will likely make their dysfunctions worse by sitting on an uneven surface. So, those with underlying issues are likely to experience more pain.

 How do you prevent this?

Now some people may think “..so I cannot use a wallet ever?”. The answer is of course “Yes you can.”
Just take your wallet out of your pocket when you sit, especially before you drive.If you’re going to be sitting for 15 minutes or less, don’t worry too much about your wallet in your back pocket. If that time exceeds 15-20 minutes, however, switch that wallet into your shirt pocket.

Keeping your pelvis and spine level is extremely important to maintain healthy spinal alignment, to keep good posture and to decrease the risk of back pain.