A semen allergy — otherwise known as human seminal plasma hypersensitivity (HSP) — is an allergic reaction to the proteins found in most men’s sperm.

The rare condition is more common in women, affecting up to 40,000 women in the United States. It’s unclear how extensively this condition affects men who have sex with men.

Studies do show that it’s possible to be allergic to your own semen. When this happens, it’s known as a post-orgasmic illness syndrome.

Keep reading to learn how to recognize the symptoms, your options for treatment, how this may affect your ability to conceive, and more.

You may be having an allergic reaction if you experience one or more of the following symptoms after exposure:

  • redness
  • burning
  • swelling
  • pain
  • hives
  • itching

For women, symptoms usually occur on the vulva or inside the vaginal canal. For men, symptoms may occur on the shaft or the area of skin above the genitals.

That said, symptoms may appear anywhere that has come in contact with semen. This may include your:

  • hands
  • mouth
  • chest
  • anus

Allergic reactions to semen are often localized, but some people may experience symptoms that affect their whole body. For example, men who are allergic to their own semen may experience severe fatigue, intense warmth, and a flu-like state right after ejaculation.

Overall, symptoms usually start within 20 to 30 minutes of exposure. They may last anywhere from a few hours to several days, depending on the severity.

Severe allergic reaction

In severe cases, anaphylaxis is possible. Anaphylaxis symptoms typically appear within minutes of exposure and require immediate medical attention.

Anaphylaxis symptoms include:

  • difficulty breathing
  • wheezing
  • swollen tongue or throat
  • rapid, weak pulse
  • dizziness or fainting
  • nausea
  • vomiting
  • diarrhea

Semen allergies are primarily caused by proteins found in a man’s sperm. Some research also suggests that certain medications or food allergens found in sperm can trigger symptoms.

Beyond having unprotected sex, risk factors for HSP aren’t clear.

It’s possible for semen allergy to develop in women who haven’t had any prior symptoms after exposure to seminal fluids. You may also experience symptoms with one partner and not another.

Although semen allergies can develop at any time, many women report that their symptoms began during their early 30s. Older research found that many women with the disorder also experienced recurrent vaginitis prior to diagnosis.

If you’re experiencing unusual symptoms after coming into contact with seminal fluid, make an appointment to see your doctor.

If you think your symptoms are the result of a semen allergy, it’s important to speak up. Be honest with your doctor about your symptoms, and be clear about when they occur.

Research on HSP is lacking, which can make diagnosis difficult. It isn’t unheard of for doctors to mistake a semen allergy for:

  • sexually transmitted infections like chlamydia or herpes
  • chronic vaginitis
  • yeast infection
  • bacterial vaginosis

If you feel as though your concerns aren’t being heard, ask your doctor to schedule a skin prick or intradermal test.

To do this, your doctor will need a sample of your partner’s semen. Your doctor will inject a small, diluted amount of this sample under your skin. If symptoms appear, your doctor can make a HSP diagnosis.

If the test doesn’t trigger symptoms, your doctor may take a blood draw or pursue other diagnostic testing.

Treatment for HSP aims to minimize or prevent symptoms. The best way to do this is to wear condoms every time you have sex. Men who are allergic to their own semen should also wear a condom during masturbation, though this may not prevent some body-wide symptoms.

Desensitization

If you prefer not to wear a condom, talk to your doctor about your options for desensitization.

To do this, your allergist or immunologist will place a diluted semen solution inside your vagina or onto your penis every 20 minutes or so. This process will continue until you’re able to withstand exposure to undiluted semen without experiencing symptoms.

After the initial desensitization, consistent exposure is necessary to maintain your tolerance. For example, people who are allergic to their partner’s semen will have to engage in intercourse every 48 hours.

Medication

Your doctor may also recommend that you take an over-the-counter antihistamine prior to any sexual activity. This may help minimize your symptoms, especially if you or your partner opt against using a condom to prevent exposure.

If your symptoms are severe, your doctor may recommend that you carry an EpiPen. You should inject this at the first sign of severe symptoms, and then seek immediate medical attention.

A semen allergy can make it difficult for some women to conceive. Although the allergy doesn’t have any impact on fertility, its symptoms can interfere with your ability to have sex.

In mild cases, you may be able to take medication or use desensitization to help ease your symptoms.

But if you wish to conceive and intercourse isn’t an option, your doctor may recommend intrauterine insemination (IUI) or in vitro fertilization (IVF).

In both cases, your partner’s sperm will be washed free of proteins before it’s injected. This can help prevent an allergic reaction.

Success rates vary for IUI and IVF, so talk to your doctor about what’s best for you.

With IVF, the average woman has a 20 to 35 percent chance of becoming pregnant after one cycle. With IUI, there’s a 5 to 15 percent chance of conception after one cycle.

A semen allergy can cause anaphylaxis if the condition is severe. You should seek immediate medical attention if you begin experiencing:

  • difficulty breathing
  • wheezing
  • swollen tongue or throat
  • rapid, weak pulse
  • dizziness or fainting
  • nausea
  • vomiting

Having a semen allergy can also have a negative impact on your relationships.

If the disorder makes it difficult to be intimate with your partner, you may find it helpful to participate in couple’s therapy. Your counselor can help you and your partner navigate this diagnosis and explore other options for intimacy.

It isn’t clear whether this allergy can be passed down to your children.

A semen allergy is a rare condition that, like any allergy, can develop or fade over time. If you’re experiencing symptoms, it’s important that you see your doctor for diagnosis.

If left untreated, a semen allergy can disrupt your sex life and affect your overall well-being. Your doctor can work with you to develop a plan for symptom management, as well as discuss your options for family planning.