Priapism is a painful and dangerous condition in which an erection fails to subside. This can be a symptom of leukemia or sickle-cell anemia, but can also be caused by abuse. Erections should not last longer than four hours because the blood can start clotting, then reducing the erection is very difficult. A shot of pseudoepinephrine might do the job, but if not, aspiration with a huge needle, or even surgery to literally carve the blood clots out, may be required.