I take one alleve tablet a day is this bad? i take it for knee pain.

No it's not. : No, if it's just one a day your fine.

Depends: on your other medical conditions so you need to check with your doctor. If it ok with your doctor make sure you take it with food.

Not bad at all: Naproxen is a traditional NSAID. It works by blocking your body's production of some natural substances that cause inflammation. It is great an anti-inflammatory drug and reduces pain, swelling, and joint stiffness caused by arthritis. If concerned, talk to your PCP for more information. Good luck.