Bleeding gums is a symptom of gum disease that is caused by bacteria and plaque buildup along the gum line. It usually starts with redness and swelling of the gums, followed by bleeding when brushing or flossing. Over time, the gums may recede, causing pockets to form between the teeth and gums where bacteria can accumulate, leading to further infection. Bleeding gums can also be caused by vitamin deficiencies, hormonal changes, and certain medications. Treatment depends on the cause, but usually involves improved oral hygiene, antibiotics, and/or surgery.