Is a red line running up you L arm sign blood poisoning?

Not necessarily. A red line running up your arm could be a sign of superficial thrombophlebitis, which is a blood clot in a superficial vein. It is usually not a sign of blood poisoning (sepsis), which is a serious infection of the bloodstream. However, if the red line is accompanied by other symptoms of blood poisoning, such as fever, chills, and confusion, it is important to seek medical attention immediately. Signs of thrombophlebitis usually disappear within 2 to 4 weeks. If signs continue for longer than 2 weeks, talk to your doctor. Some people have recurring thrombophlebitis that comes and goes over many years