Hello and welcome to MedHelp's forums. Nipple discharge in men needs to be evaluated by a doctor. It is very rare in men but is a symptom of breast cancer, not to worry or scare you. Please consult your doctor immediately. https://www.healthline.com/health/nipple-discharge-in-males.
Let us know how you are doing.
Probably not serious. Guys can have breast cancer, but if, as in your case, both breasts are involved it probably isn't cancer. But you should be concerned about cancer if only one nipple secreted.