Can swallowing semen cause pregnancy?

Semen is male ejaculate that is expelled from the tip of the penis during orgasm. The fluid contains spermatozoa (sperm cells) that swim through the seminal fluid once discharged into the vagina.

The terms “sperm” and “semen” are often used interchangeably when referring to male ejaculate, even though they technically refer to different things.

Sex can get pretty messy. When you’re performing oral sex, it’s perfectly normal to get some semen in your mouth and swallow it.

You shouldn’t be too worried about swallowing semen. From a nutritional standpoint, there is nothing harmful about ingesting semen. There are actually some benefits to ingesting semen, including improved mental health, since semen can contain chemicals tied to improved mood, like serotonin.

However, it gets trickier when we start thinking about other areas of our health.

You can’t get pregnant from swallowing sperm or by performing anal sex. So, if you’re worried about that, you can put your mind at ease.

As a woman, you can only get pregnant if you engage in sexual intercourse (vaginal sex) without birth control or some form of contraception, like condoms or the birth control pill. (These methods are not always 100% effective.)

How women get pregnant

After male ejaculation into the vagina, millions of sperm are released into the vagina, beginning their journey toward potential fertilisation. Within minutes, sperm begin swimming through the cervix and into the uterus.

Only a few hundred of the strongest sperm make it to the fallopian tubes, where they may encounter an egg if ovulation has recently occurred during the woman’s menstrual cycle. This is the critical moment: if a sperm successfully penetrates the egg’s outer layer, fertilisation takes place, forming a zygote—the very first stage of human development.

Following fertilisation, the zygote begins dividing and travels down the fallopian tube toward the uterus, where it may implant into the uterine lining. This process, known as implantation, typically occurs about six to 10 days after intercourse. If implantation is successful, pregnancy begins.

However, it’s important to remember that not every instance of unprotected sex leads to pregnancy. Timing, fertility, and other biological factors all play a role.

While you can’t get pregnant from swallowing semen, you can get something else: a sexually transmitted disease.

Many people believe that sexually transmitted infections can only be passed on during penetrative sex, but this isn’t the case. You can easily get an STI from oral sex, which includes swallowing semen.

How this works is pretty simple. Many STIs only require the presence of a mucous membrane or an open wound to be passed on. These mucous membranes include those in the eyes, throat, rectum, and genitals.

In this manner, infected bodily fluids that come into contact with mucous membranes can transmit an infection. So, if infected semen comes in contact with the mucous membranes in your throat, it’s very possible that you will contract an infection.

It’s technically possible to get any number of STIs from swallowing semen. However, some are more likely than others.

STIs you can get from swallowing semen include:

Chlamydia

When someone performs oral sex on a partner who has a Chlamydia infection in their genitals, the bacteria can be passed to the throat.

Gonorrhoea

If you perform oral sex on a partner with a genital Gonorrhoea infection, the bacteria can infect the throat. Likewise, if a person has Gonorrhoea in their throat, they can transmit it to their partner’s genitals during oral sex, though this is very rare.

Herpes

If someone has oral Herpes (typically caused by HSV-1), they can pass the virus to their partner’s genitals during oral sex. Likewise, genital Herpes (often caused by HSV-2) can be transmitted to the mouth. Because Herpes can be spread through skin-to-skin contact and viral shedding, transmission is possible even without visible sores.

HPV

Human Papillomavirus (HPV) is the most common sexually transmitted infection in the world and can be passed on through oral sex, even when no symptoms are present. The virus can infect the mouth and throat when there is skin-to-skin contact with an infected partner’s genitals. Certain strains of HPV have been linked to oral, throat, and cervical cancers, making awareness and prevention especially important.

HIV

While the risk of Human Immunodeficiency Virus (HIV) transmission through oral sex is lower than with other forms of sexual contact, it’s still possible. HIV can be passed on if the virus is present in semen, vaginal fluids, or blood and enters the body through cuts or sores in the mouth or throat.

Hepatitis B

Hepatitis B is a highly infectious virus that can be transmitted through oral sex, even if no symptoms are present. Like with HIV, transmission is more likely during oral sex if there are cuts or sores in the mouth. Because Hepatitis B can cause serious liver complications, including chronic infection and liver cancer, vaccination and regular testing are vital.

Syphilis

Syphilis is a bacterial infection that can be transmitted through oral sex. The bacteria responsible for Syphilis, Treponema pallidum, can enter the body through contact with a chancre, a firm, round, and painless sore that appears at the site of infection – usually the mouth, anus, or genitals.

Trichomonas

Trichomonas, caused by the parasite Trichomonas vaginalis, is an overlooked sexually transmitted infection that can potentially be passed through oral sex. While it is most commonly transmitted through vaginal intercourse, the parasite may also be spread when the mouth comes into contact with infected genital areas.

While you can’t get pregnant from swallowing semen, you can get other things, like STIs. You should take precautions when engaging in any kind of sexual activity and use contraception where possible to prevent pregnancy. When performing oral sex, you can use condoms and dental dams to create a protective barrier between you and your partner.

If you have swallowed semen and believe you may have been exposed to an STI, get tested today.

This blog first appeared on 13/09/2023. Last updated 01/08/2025.