<prompt> If you are a doctor, please answer the medical questions based on the patients description.it is disease that when i go to toilet and after urin comes out sperm.if it is disease then which disease. and also one thing more i have alergy from six years.when i draw some line on my skin then after aftr 5 mints red strips like artery comes out, and after 15 mints then become normal.  <response>: Hello Thank you for trusting Chat Doctor The basic cause of semen leakage is the overstimulated functioning of the parasympathetic nerves. The parasympathetic nerves aid in keeping the ejaculation valve closed, thereby helping a man to maintain his erection during sexual performance. But over stimulation weakens the nerves, and they can no longer keep the valve tightly shut. Consequently, semen leaks out. You also have dermatographia it may be due to emotional stress and infection. Please consult your doctor he will advise correct treatment after investigations. 