There are many reasons for red gums, such as dietary factors, periodontitis, mouth ulcers, herpes and other causes. 1. Dietary factors: For example, taking too cold, too hot, too hard food, physical stimulation can lead to red gums. 2. Periodontitis: Infectious diseases such as gingivitis, periapical periodontitis, pulpitis, etc. can cause localized gum congestion and swelling, which can cause red gums. 3. Mouth ulcers: Mouth ulcers caused by various reasons may also cause ulcers around the gums, which can also lead to red gums. 4. Herpes: Viral infections such as oral herpes can also cause red gums. There may be other reasons for red gums, you need to go to the hospital in time to check, follow the doctor’s instructions for treatment.