There are many reasons for bleeding after sex, which may be caused by vaginal injury, vaginitis, cervical disease, etc. Patients should seek medical attention for a clear diagnosis. 1. Vaginal injury: hymen rupture, violent sexual activities, etc. may lead to vulvar injury, and patients have symptoms such as bleeding after sexual intercourse. 2. Vaginitis: may be due to bacterial, fungal, trichomonas infection, patients often have vaginal itching, pain, abnormal vaginal discharge, pain during sexual intercourse, and occasionally bleeding after sex. 3. Cervical diseases: women suffering from cervicitis, cervical polyps or cervical precancerous lesions and cervical cancer and other diseases, due to the cervical mucosal tissue congestion, edema, become fragile, will stimulate the appearance of contact bleeding phenomenon after intercourse, and will be accompanied by increased secretion, irregular bleeding or bad smell and other symptoms. Cervicitis can be treated with anti-erosion suppository and anti-uteritis tablets; cervical polyps are recommended to be removed surgically and then analyzed pathologically; while pre-cancerous lesions of the cervix and cervical cancer caused by cervical cancer are recommended to be treated with surgery or radiotherapy, and so on. There may also be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.