This is coming from a pharmacology grad... make of it what you will.
Some classes of painkillers (COX-2 inhibitors) are associated with increase risk of cardiovascular problems... specifically myocardial infarctions. So if you have disposition for a weak heart, take older generation painkillers (e.g. asprin, ibuprofen) instead.
Vicodin according to Wikipedia is a mixture of hydrocodone and acetaminophen. It's used for treating moderate to high pain. It's generally safe to use provided you keep to the dosage subscribed by your doctor and do not mix it with any other drugs (including alcohol). It may cause speed up heart rate and dizziness. Again this is worse if you mix it with other drugs that acts on the same system. However, assuming you're young and healthy, you shouldn't get any problems. So if you're in a lot of pain, take it. If you can get away without, take just acetaminophen or nothing at all.
ps - blood? You mean bleeding? NSAIDS (asprin, ibuprofen, COX-2 inhibitors) impairs blood clotting and prolong use (months on end) can lead to gastrointestinal bleeding. Acetaminophen is a little better... just don't do something silly like taking 20 of them at the same time