Appropriate masturbation is not harmful to the body. However, excessive and frequent masturbation may cause urinary tract infection, lead to male infertility, lead to penile sensitivity, affect the mental state, lead to genital damage, etc.. 1. cause urinary tract infection: long-term frequent masturbation, may lead to bacteria into the urethra, resulting in urinary tract infection, serious will also cause prostatitis, seminal vesicles and so on. For girls may cause vaginal inflammation, pelvic inflammation and so on. 2. lead to male infertility: long-term masturbation makes male ejaculation frequency greatly increased, the quality of sperm decreases, and in serious cases may lead to normal sex male can not ejaculate or sperm quantity is very small, cause male infertility. 3. lead to penile sensitivity: men often masturbate in order to only seek a quick and take a simple and rough way, each masturbation may cause different degrees of damage to the penis, long-term may lead to penile oversensitivity and cause premature ejaculation. 4. affect the state of mind: long-term masturbation will also affect the state of mind of men, so that they lose vitality, the whole day decadence and fatigue, and some will also have the symptom of memory loss. 5. lead to genital injuries: boys are common for the foreskin and foreskin tie crack bleeding, occasional penile fracture, etc., may also affect the normal sexual intercourse after marriage, if not cured as soon as possible may lead to erectile dysfunction. Appropriate masturbation can solve their physiological needs, can relieve physiological pressure and psychological pressure, generally no harm. If too frequent masturbation may cause harm to the body, if masturbation after the body does not adapt to timely medical treatment.