What’s in semen (cum)?

For some people, performing oral sex on a male partner includes swallowing semen. And that leads them to wonder- what’s in that stuff?

When a man typically ejaculates, he produces about one teaspoon of semen. The amount of fluid can vary based on his age, the last time he ejaculated, and lots of other factors. The fluid is made of:

  • Millions of sperm which are made in the testes
  • Proteins, enzymes and fructose that come from the seminal vesicles
  • Enzymes and zinc from the prostate gland
  • Mucus from the bulbourethral glands.

A typical ejaculate contains about 5 calories, which is about the same amount of calories as in one small sip of soda. (Need a refresher on the parts of the male genitals? Read and see more about the internal and external parts.)

Whether or not you decide to swallow semen, having unprotected oral sex still can transmit infections like gonorrhea, chlamydia, syphilis, HPV and HIV. This can happen because the pre-cum or the cum may contain these bacteria and viruses even if everything feels and looks normal. Also, there can be small breaks in the skin of the mouth and/or penis that may not be visible to the eye, but may expose one partner’s blood to the other. Using a non-lubricated condom or a dental dam is the safest way to have oral sex.

Finally, talking to your partner about oral sex before you get started is absolutely the right way to go. Maybe you’ve always been too embarrassed? Here are some ways to get started talking. It’s always a great idea to check in with yourself: How do you feel about oral sex? How can you and your partner make sure that it’s right for both of you?