PCOS is often associated with excess body hair, menstrual irregularities, and acne. Hives are a possible, although less common, symptom.

PCOS occurs when the ovaries produce irregular amounts of testosterone and other androgens. This disrupts the menstrual cycle, which can lead to imbalanced levels of:

  • estrogen
  • progesterone
  • follicle-stimulating hormone
  • luteinizing hormone

The endocrine system — the system responsible for hormone production — helps manage mood, growth and development, organ function, metabolism, sex and reproduction, and more, explains hormone specialist and integrative nutritionist Alisa Vitti, author of “In the FLO” and “WomanCode.”

So, when this system is disrupted, it can trigger various symptoms across different areas of the body.

Hives, for example, are particularly common in people with increased estrogen production, explains Abby Grimm, a registered dietitian with FWDfuel Sports Nutrition.

Hives are often a physical manifestation of having high histamine levels, says Vitti.

Histamine is a chemical produced by the immune system. The body can produce higher levels of histamine when an unrecognized protein enters the system through the air or ingestion.

The naturally occurring enzyme diamine oxidase (DAO) usually breaks down histamine. This helps restore balance before hives and other symptoms related to high histamine levels occur.

Unless the histamine-DAO ratio is imbalanced — and that’s where PCOS comes in.

Some people with PCOS produce too much estrogen and low levels of progesterone, explains Grimm. Together, these two hormones can create higher-than-usual levels of histamine in the body.

“Estrogen triggers histamine production from mast cells,” she says. So, when your estrogen levels are higher, histamine levels are higher, too.

“Progesterone supports the release and production of DAO,” explains Vitti. When progesterone levels are low, as they are in some people with PCOS, DAO levels are low, too.

As a result, histamine levels stay high, which can lead to hives.

You can help treat hives at home with an over-the-counter oral antihistamine and anti-itch cream.

If you have high estrogen levels, the most common way to prevent future occurrences of hives is to address your high estrogen levels, says Grimm.

“People can begin to address their estrogen dominance by following a PCOS-friendly, low-histamine diet,” she says.

This might involve adding or increasing your intake of:

This might also involve limiting your intake of:

If you have PCOS and suspect your hives may be related, it’s important to consult with a healthcare professional.

They can test your hormone levels and order an allergy test to determine whether an undiagnosed allergy could be the root cause.

Seek emergency medical attention if you experience:

  • difficulty swallowing
  • swelling in your mouth or throat
  • lightheadedness
  • racing heart

These additional symptoms suggest that you may have anaphylaxis, which can be life threatening and requires immediate care.

Gabrielle Kassel (she/her) is a queer sex educator and wellness journalist who is committed to helping people feel the best they can in their bodies. In addition to Healthline, her work has appeared in publications such as Shape, Cosmopolitan, Well+Good, Health, Self, Women’s Health, Greatist, and more! In her free time, Gabrielle can be found coaching CrossFit, reviewing pleasure products, hiking with her border collie, or recording episodes of the podcast she co-hosts called Bad In Bed. Follow her on Instagram @Gabriellekassel.