Because the male and female reproductive systems are different, many sexually transmitted infections affect men and women differently. For instance, women often have more serious health problems from STIs than men.
The female reproductive system, being mostly inside the body, is more susceptible to invading bacteria and viruses and provides a better environment for bacteria to grow. This can also mean symptoms are less visible in women, making it more likely that their infection will go untreated.
The male reproductive system, on the other hand, is mostly outside the body, where bacteria and viruses don't penetrate or grow as easily. Because symptoms are more visible on the outside of the body, men are more likely to seek treatment early, which can prevent further complications.
You can learn more about the female and male reproductive systems in this section.