There aren't side effects to masturbating, it's normal. Your body constantly remakes sperm, you won't run out, no side effects. But be careful if you watch porn or have other stimulants, you will start getting bored with it and may need more strange or extreme things to get off.
Huh? I didn't realize that women made sperm, weird... Oh that's right; they don't. So your info, although mostly accurate, is not completely true. :) F/O/D/S!
nou3 - As far as masturbating 10x a day, no there shouldn't be any negative effects on your fertility. Although you may want to discuss this with your doctor to get an idea about the root cause of your high libido. Is your level of sexual desire just natural for you; or is there a psychological or hormonal cause.
Side effects would be temporary abrasion or strain injury depending on how aggressive you are. You'd have to be very aggressive to cause any real injury; and you'd know it if you did.