What are the consequences of chronic over-masturbation?

Several. An unhealthy lifestyle, mental stress, relational stress, physical damage to the sex organ, poor performance at the work place, withing the family or in relationships in general. You would have to define "over-masturbation" though. What some would consier "over" may be normal for someone else. Discuss with your pcp, counsellor, clergy, mentor or health/mental health counsellor.