A cactus needle pierced a blood vein on my hand and it is swollen and aching....What should I do? I am a 65 year old female in good health

Let me help you. When this happen most likely you slight infection in the area, this why is swollen and painful, you keep it clean and soak it with h2o2 and water two to three times a day. Get hold of your doctor and ask him to give you some anti-biotic. Good luck.