Is it dangerous if heart reacts too sensitive to everything if its nothing wrong with heart? heart goes up and down like its overreactive.

It's supposed to: Your heart rate is supposed to go up and down as things happen to you. You've just reached the age of manhood. I would hope that things happen to you that make your heart race! women, sports, friends, and even learning leading to a successful career should all excite you. If you have more than five strange heartbeats in a minute, or you get short of breath, ask your physician. Otherwise, enjoy!