The gums are swollen with blood but do not hurt, considering the occurrence of gingivitis, wisdom teeth pericoronitis, periodontal abscess and other diseases. 1. Gingivitis, clinical gingivitis after the deposition of dental calculus plaque, may lead to swelling and bleeding of the gums, so this symptom will appear. 2. Wisdom tooth pericoronitis, patients with wisdom tooth pericoronitis due to inflammation stimulation of the pericoronary area, may lead to gum tissue damage, so there will be blood swelling of the gums, but not painful symptoms. 3. Periodontal abscess, if there is a periodontal abscess, periodontal secretions gathered swelling, compression of the gums, may lead to capillary rupture bleeding, the gums appear hematoma but not painful symptoms. If there are obvious symptoms of discomfort, it is best to consult a doctor in time for examination and treatment.