There are many reasons for red but painless gums, such as chronic gingivitis, blood diseases, dental calculus and so on. 1. Chronic gingivitis: Chronic gingivitis can cause red but painless gums, but acute attacks can cause pain. 2. Blood disorders: Some blood disorders can also cause red but painless gums, such as leukemia, which requires a thorough examination to confirm the diagnosis. 3. Calculus: Calculus can irritate the gums and therefore may cause red but painless gums. Gums red but not painful for many reasons, after the emergence of symptoms, it is recommended to go to the hospital in a timely manner to improve the examination, in accordance with the doctor’s instructions to take standardized treatment, do not ignore the symptoms, take it lightly, in order to avoid inducing adverse consequences.