If your gums bleed when you brush, it may be a sign of gum disease or other oral health problems. Here are some possible reasons why your gums may be bleeding:

1. Gingivitis: Gingivitis is a mild form of gum disease that is caused by the buildup of plaque and bacteria on the teeth. Symptoms may include bleeding gums, redness, and inflammation.

2. Overbrushing: Brushing your teeth too vigorously or using a hard-bristled toothbrush can irritate your gums and cause them to bleed.

3. Vitamin deficiencies: Vitamin deficiencies, particularly in vitamin C and vitamin K, can cause bleeding gums.

4. Medications: Certain medications, such as blood thinners or aspirin, can increase the risk of bleeding gums.

5. Hormonal changes: Hormonal changes during pregnancy or menopause can cause gums to become more sensitive and prone to bleeding.

6. Poor oral hygiene: Poor oral hygiene habits, such as not brushing or flossing regularly, can lead to the buildup of plaque and bacteria on the teeth, which can cause bleeding gums.

If you are experiencing bleeding gums, it's important to talk to your dentist or oral health professional. They can evaluate your oral health and recommend appropriate treatment, such as a deep cleaning or periodontal therapy, to address the underlying issue and improve your gum health. In the meantime, make sure to brush and floss regularly, and use a soft-bristled toothbrush and gentle brushing technique to avoid further irritation.