How bad is a heart murmur? how important is treatment or going to the doctor for it?

Murmur Common: Many are Benign, some are not. You need a Cardiologist to listen, you may need a sonogram of UR heart (echocardiogram) - simple test. The echo is best way to follow a murmur that is not currently important but could become important in later years.

Depends: There are a large group of people with innocent heart murmurs that will not have any specific effect on their life. A few, with complex murmurs, (usually from congenital heart disease)should/would have been warned by their docs in early life .Not knowing how this applies to you limits the answer.Maybe you should ask your doc.