Itchy eyes. Runny nose. Congestion that won’t quit.
For millions of Americans, spring means it’s allergy season. And if your symptoms get worse with each passing year—or they appeared during adulthood when you never had allergies before—your hormones may be to blame.
The connection between hormones and allergic responses is one that doesn’t get much attention. But for people coping with worsening seasonal allergies, understanding this link could be the missing piece of the puzzle.
How the Immune System and Hormones Are Connected
Your immune system and your endocrine system (i.e. the system responsible for producing your hormones) are in constant communication with each other. Hormones influence immune system function at nearly every level, including how aggressively your immune system responds to perceived threats like pollen, dust, and other allergens.
When hormones are balanced, the immune system tends to respond proportionately to genuine threats, while standing down against harmless environmental triggers. But when hormones are out of balance, that calibration sometimes goes haywire—leaving the immune system in a state of chronic overreaction.
This is why the hormonal shifts associated with age-related hormone imbalance are often accompanied by changes in allergy symptoms. It isn’t a coincidence. It’s biology.
The Complicated Relationship Between Estrogen and Histamine
Of all the hormones involved in allergic responses, estrogen has the most direct and well-documented connection.
Here’s why:
Estrogen stimulates the production of histamine—the chemical your immune system releases in response to allergens. Histamine is what causes the itching, sneezing, congestion, and watery eyes associated with allergic reactions.
But the relationship goes both ways. Histamine also stimulates the production of more estrogen. This creates a feedback loop that can amplify both allergic symptoms and estrogen-related symptoms simultaneously.
For women in perimenopause, this dynamic can be particularly problematic. Fluctuating estrogen levels—which are characteristic of perimenopause — can trigger unpredictable spikes in histamine production, making allergy symptoms feel erratic and difficult to manage.
Additionally, as progesterone declines during perimenopause, its natural counterbalancing effect on estrogen is diminished. Since progesterone helps to modulate immune system responses and has a natural antihistamine effect, low progesterone means less natural protection against histamine overproduction.
Cortisol as Your Body’s Built-In Antihistamine
Here’s something most people don’t know: cortisol is actually a natural anti-inflammatory and antihistamine. In healthy amounts, cortisol helps to keep allergic responses in check.
This is why corticosteroids—which are synthetic versions of cortisol—are commonly prescribed for severe allergic reactions and inflammatory conditions.
But when cortisol production is dysregulated due to chronic stress or adrenal fatigue, this natural antihistamine effect is compromised. People with depleted or dysregulated cortisol often find that their allergy symptoms are more intense and harder to control. This is because their body’s built-in dampening mechanism isn’t functioning as it should.
Managing chronic stress and supporting adrenal health can therefore have a direct and meaningful impact on allergy severity.
Testosterone and Immune System Modulation
Testosterone has anti-inflammatory properties that help to modulate immune system responses. Research suggests that higher testosterone levels are associated with less aggressive immune system reactions—which may help to explain why men, on average, tend to experience less severe allergic responses than women during their reproductive years.
As testosterone declines with age in both men and women, this moderating effect on the immune system diminishes. The result can be worsening allergy symptoms that seem to come out of nowhere in midlife—even in people who had few issues with allergies when they were younger.
For women, this is compounded by the fact that testosterone levels often drop significantly during perimenopause, alongside estrogen and progesterone.
Thyroid Dysfunction and Allergy Symptoms
Thyroid imbalances add another layer of complexity. Hypothyroidism (i.e. low thyroid function) can dampen immune system regulation and increase the likelihood of immune system overreaction. Some research has found a meaningful association between thyroid disorders and allergic conditions including asthma, eczema, and allergic rhinitis.
If you have known thyroid issues and find that your allergy symptoms are worsening, it’s worth considering whether your thyroid treatment is truly optimized.