An increase in vaginal discharge after sex and a change in its nature are likely to be caused by acute vaginitis and should be clarified by a vaginal discharge routine. The normal vagina is weakly acidic and the dominant flora is Lactobacillus. After sex, especially when sperm are kept in the vagina, the vaginal environment will be changed and the vagina will become less self-cleaning and susceptible to bacterial infection and inflammation of the reproductive tract. If a woman’s immune system is normal, the normal vaginal flora can be restored soon to curb the growth of harmful bacteria and the inflammation can heal itself. However, if a woman has poor immunity or has vaginitis before sex, vaginitis will be aggravated acutely after sex, and symptoms such as itching and odor may occur along with increased vaginal discharge. Therefore, it is recommended to pay attention to sexual hygiene and to take certain protective measures, such as using condoms, if the sexual partner has inflammation of the reproductive tract.