Bleeding during sex can happen for several reasons, most commonly related to the cervix, vagina, or hormonal changes. Key causes include:

• Cervical irritation or infection (cervicitis) often from sexually transmitted infections like chlamydia or gonorrhea, which cause inflammation and bleeding.
• Cervical polyps , which are small, noncancerous growths on the cervix surface that can bleed during sex.
• Vaginal dryness or insufficient lubrication , leading to friction, small tears, or vaginal wall irritation, especially common during menopause, breastfeeding, or hormonal contraceptive use.
• Cervical ectropion , where the inner lining of the cervix grows outward, making the cervix more fragile and prone to bleeding.
• Other factors include genital sores, uterine or cervical cancer or precancerous cells, pelvic inflammatory disease, trauma or injury during sex, and incorrect placement of intrauterine devices (IUDs).

If bleeding during or after sex is frequent, heavy, or accompanied by other symptoms like pain or unusual discharge, it is important to see a healthcare provider for diagnosis and treatment options.