Here’s a question you never thought you’d ask: Can you be allergic to semen? While super rare, it’s entirely possible to be allergic to your partner’s reproductive fluids if they have a penis. You may experience symptoms like itching, burning, or swelling “down there,” or in extreme cases, trouble breathing—a reaction called anaphylaxis. If this all happens after sex, your partner’s semen might be to blame.

A semen allergy—also known as seminal plasma hypersensitivity—can cause anything from discomfort in your genital and anal region to full-body allergic responses. It may sound scary, but don’t worry: This type of allergy can be managed in a variety of ways, depending on its severity.

Not sure if this is what’s happening to you? Read on to learn what a semen allergy is like, how it’s diagnosed, and what you can do to keep things comfortable (and safe) in the bedroom.

What causes a semen allergy?

A semen allergy is your immune system’s reaction to the proteins in your partner’s seminal fluid, not the actual sperm, says Maureen Whelihan, MD, FACOG, an OB/GYN and American College of Obstetricians and Gynecologists (ACOG) fellow based in Florida. Semen allergies can irritate not just the skin around your genitals but also anywhere semen touches, like your hands or even the sensitive tissues inside your mouth and throat. Experts aren’t exactly sure why this happens, but possible culprits include certain medications or hormonal changes like pregnancy or menopause.

According to Dr. Whelihan, food sensitivities might play a role here, too. For example, if you have a peanut allergy and have sex with a partner who ate peanuts, trace amounts of the nuts can come across in body fluids (like semen) and trigger an allergic reaction, she adds.

There are different types of semen allergies

Research shows that there are two forms of semen allergy: localized and systemic. While some people experience a localized allergy (aka a reaction only on the skin that comes into contact with semen), others experience a whole-body—or systemic—response. Here’s a breakdown of what each entails:

• Localized: Affects only areas in direct contact with semen, like the genitals, hands, or lips, causing burning or stinging sensations.
• Systemic: Hits the whole body, with symptoms like trouble breathing, swollen lips or tongue, hives, or even anaphylactic shock, a severe, potentially life-threatening allergic reaction (more on this later).

While both can be series and warrant a visit to your healthcare provider, systemic reactions require immediate medical attention.

What are the symptoms of a semen allergy?

As noted, many of the symptoms of a semen allergy resemble those of other allergic reactions, including the following, per Dr. Whelihan:

• Itching, redness, swelling, or burning skin
• Hives
• Swollen lips or tongue
• Trouble breathing
• Dizziness
• Nausea, vomiting, or diarrhea

It’s rare for a semen allergy to trigger anaphylactic shock, but if you happen to notice symptoms like a swollen throat, weak pulse, or loss of consciousness, seek immediate medical attention at your nearby emergency room.

How fast do the symptoms show up? You’ll typically notice them within 30 minutes of contact (i.e., after sexual activity), and they can last hours to days. In some cases, you might notice signs of an allergic reaction the first time you have sex without a condom. But semen allergies can also happen out of the blue (even if you didn’t have one in the past), such as after menopause or childbirth. Interestingly, it can also affect you with some partners but not with others.

Just keep in mind: A post-sex rash or irritation doesn’t always mean you have a semen allergy, Dr. Whelihan says. More than likely, irritation is from either an infection or skin irritant (like the lube you’re using or latex from the condoms) causing the issue. If you’re unsure of the cause, your healthcare provider can help you figure it out.

Who’s most at risk for a semen allergy?

While anyone who has unprotected sex can have a semen allergy, it’s exceedingly rare and tends to affect people with a vagina or who “suffer from other allergies (immune system problems),” Dr. Whelihan says. While some reports have estimated that about 40,000 people with vaginas in the U.S. have a semen allergy, this number could be higher since some people feel embarrassed to bring the topic up with their healthcare provider.

In even rarer cases, people with a penis who produce semen can be allergic to their own seminal fluid—a condition called post-orgasmic illness syndrome. Symptoms of this condition can happen within minutes to hours of ejaculation and last for up to seven days.

Can it cause infertility issues?

Thankfully, being allergic to semen cannot directly contribute to infertility—i.e., difficulty getting pregnant. That said, having this type of allergy can make conception a bit trickier, especially if you have a severe systemic allergy that puts your life at risk. Luckily, there are many options to help you get pregnant.

The first fertility option is a treatment called intrauterine insemination (IUI), which involves doctors extracting sperm, “washing” them in a medical lab to remove problematic proteins, and then injecting them directly into your uterus, Dr. Whelihan says. Other options—also known as assisted reproductive technologies (ART)—include treatments like the following:

• In vitro fertilization (IVF): a type of fertility treatment where eggs are combined with sperm outside of your body in a lab
• Intracytoplasmic sperm injection (ICSI): a type of IVF where your provider injects live sperm directly into an egg

How to treat a semen allergy

Avoiding semen is the simplest way to dodge an allergic reaction—simply use condoms or skip sex. For some people, even the pull-out method (where your partner pulls his penis out of your body before ejaculating), can be helpful, too, Dr. Whelihan says. But if you’re trying to conceive, these strategies probably won’t be the best option for you. Here’s how your healthcare provider might be able to help, according to recent research:

• Medication: Taking an antihistamine (like Benadryl) before sex can ease symptoms. If you’ve had severe reactions, your healthcare provider might prescribe an EpiPen (which is used for other types of allergic reactions).
• Desensitizing via immunotherapy: This treatment involves gradually exposing your body to diluted semen via an intravaginal treatment. Over time, it can build tolerance, but you’ll need to have sex regularly (think: several times a week) to maintain it.

Talk to your provider to figure out the best option for you.

When to see a healthcare provider

If you think you might have a semen allergy (and it’s keeping you from having sex with your partner), reach out to your healthcare provider. It may feel awkward to bring it up, but they are professionals and are there to help. Symptoms like swelling, itching, redness, or more serious symptoms like trouble breathing, nausea, or vomiting after sex can be treated.

To start, your healthcare provider will want to rule out other conditions like vaginal infections through a pelvic exam. Because semen allergies can mimic other conditions—like STIs, vaginitis, or yeast infections—a skin test (injecting a small amount of your partner’s semen under your skin) may help pinpoint the issue, per Dr. Whelihan.

Another simple test you can try at home? Use a condom during sex. If your symptoms disappear, semen could be the culprit. If not, other allergens like lubricants, spermicides, contraceptives, soaps, or even laundry detergents might be to blame. Whatever the case, your provider can help you get to the bottom of it and help you find relief.