Fireworks, a glow, and complete feelings of satisfaction — that’s what you expect to feel after sex. So when you get nauseated instead, it’s understandable if you’re worried.

Nausea after sex can affect any one — and there are (surprisingly) a lot of reasons why it can occur. Keep reading to find out more about why you may feel sick after sex and when you should see your doctor.

Nausea after sex can be the result of acute and chronic medical conditions. In addition to the potential causes listed in sections below, some causes of nausea after sex include:

If you have nausea after sex more than once, you may wish to talk to your doctor about potential underlying causes.

Here are other potential causes:

People with vaginas who feel nauseated after penetrative sex may experience an episode of vasovagal syncope. This could occur when your partner penetrates very deeply, hitting your cervix. Your cervix has lots of nerve endings that can trigger a vasovagal response.

A vasovagal response is when the body stimulates the vagus nerve. This results in lower heart rate and blood pressure, which can cause you to feel faint and nauseated. You can have a similar response after seeing blood or when straining to poop.

A vasovagal episode usually isn’t anything to worry about. However, if you find you have these episodes a lot during sex, you may need to ask your partner to penetrate less deeply the next time.

Endometriosis is a condition where tissue similar to the tissue that forms the lining of your uterus grows outside of your uterine cavity. The results can be cramping, bleeding, and pain during sex. Some people with this condition also report nausea due to pain or discomfort after sex when they have endometriosis.

Having endometriosis shouldn’t take away your ability to enjoy sex. Tips that may help:

  • taking an over-the-counter pain reliever at least an hour before sex
  • trying different positions
  • testing to see if sex is less painful at different times of the month

Although this is rare, it’s possible you could have an allergic reaction to your partner’s semen or some of the components in it.

In one documented case in 2007, a woman who was severely allergic to Brazil nuts experienced an allergic reaction to her partner’s semen a few hours after he had eaten some Brazil nuts.

In addition to nausea, signs of allergic reactions to semen include:

  • fatigue
  • skin itching, especially in or around the point of contact
  • shortness of breath ranging from mild to severe
  • genital swelling

If you have a known allergy to certain foods, it’s important your partner refrain from eating them before sex — or have your partner wear a condom — to decrease the risks for allergic reaction to that food.

It’s also possible for you to be allergic to other items, which can cause the same allergic responses. Consider getting an allergy test even if you experience non-life-threatening but persistent symptoms.

when to get help

If you have problems breathing after sex, accompanied by any of these symptoms, seek immediate medical attention.

  • fatigue
  • itchy skin
  • genital swelling

Post orgasmic illness syndrome (POIS) is a medical condition that most commonly affects men, but can occur in a small percentage of women, according to an article in the journal Translational Andrology and Urology.

The condition causes a person to experience symptoms immediately after ejaculating or having an orgasm. These symptoms include:

  • blurred vision
  • extreme fatigue
  • fever
  • mood changes
  • muscle pain
  • problems concentrating

Some people with POIS report feeling like they have the flu immediately after having an orgasm, and that can sometimes result in nausea.

Doctors aren’t exactly sure why some people experience POIS after having an orgasm. Currently, they think it may be due to an autoimmune condition where a person’s body reacts negatively to their own sperm.

Sometimes the cause of nausea after sex isn’t a physical one. Anxiety and nervousness can lead to feelings of nausea and stomach upset. Sometimes, you may feel uncomfortable having sex or having sex with a certain partner. These all have the power to trigger nausea.

Sexual aversion

There is also a condition doctors call sexual aversion disorder. This is a mental health condition where a person experiences severe feelings of anxiety and fear related to sex. Men and women alike can have this condition.

Sex is meant to make you feel good. If you find it does the opposite, it may be time to talk to a mental health professional or your doctor. Even if you feel embarrassed, don’t let that emotion keep you from getting the help you need.

Sometimes people report nausea and cramping after anal sex. This is especially true if you have a history of gastrointestinal-related conditions, such as:

  • anal fissures
  • Crohn’s disease
  • hemorrhoids
  • irritable bowel syndrome
  • ulcerative colitis

These conditions may make your bowels more prone to irritation and stomach upset that could lead to nausea.

It’s tough to predict when this could occur. If you use a water-based lubricant beforehand, this may reduce your risks somewhat. However, it’s a good idea for you to communicate with your partner to stop if you feel discomfort and if you experience significant pain.

A common misconception about getting nauseated after sex means that you are pregnant or have conceived. Since people do get morning sickness when they’re pregnant, it’s easy to think that maybe you could be pregnant if you feel sick after sex.

However, feeling sick after sex doesn’t mean you’ve conceived at that moment. It takes more time for semen’s sperm to fertilize an egg and implant in the uterus.

While it’s not impossible that you could be pregnant while you’re having sex, at conception you shouldn’t have an immediate reaction that would cause you to feel nauseated.

Women and men alike have reported they’ve experienced nausea after sex. If you’re one of them, talk to a healthcare provider about potential underlying causes. With time and treatment, you can help ensure sex is all fun and no nausea.