Why Allergies and Food Intolerances Can Increase After 40: A Perimenopause Perspective

If you’d told me in my thirties that in my early forties I’d be carrying antihistamines everywhere and never leaving the house without an EpiPen, I wouldn’t have believed you.

Yet here I am at 43 (nearly 44), navigating perimenopause alongside a whole new world of allergic reactions, food intolerances, and environmental sensitivities that have genuinely changed how I live day to day. Working with the allergy clinic at Derriford Hospital in Plymouth, I’ve been diagnosed with a histamine-mediated response, including episodes of spontaneous anaphylaxis — something that can, perhaps surprisingly, be linked to hormonal changes.

This isn’t just “getting older.” For many women, the perimenopausal years can be a perfect storm for immune and inflammatory changes — and that can show up as new or worsening reactions to foods, drinks, and the environment.

Let’s unpack what’s going on.

First: Allergy vs Intolerance — They’re Not the Same

These two terms often get used interchangeably, but they involve very different processes in the body.

Allergy (Immune System Involved)

A true allergy involves the immune system producing antibodies (usually IgE) to a substance that’s otherwise harmless, like certain foods, pollens, or animal dander.

Symptoms can include:

• Hives, itching, flushing

• Swelling of lips, tongue, or throat

• Wheezing or breathing difficulty

• Vomiting

• Drop in blood pressure

• Anaphylaxis (life-threatening, requires urgent treatment)

Allergic reactions can be rapid and severe, which is why some of us now carry EpiPens.

Intolerance (Digestive/Chemical Sensitivity)

Intolerances don’t involve the immune system in the same way. They’re often due to difficulty digesting or processing certain components of food.

Symptoms are usually slower and less acute:

• Bloating

• Diarrhoea or constipation

• Headaches

• Fatigue

• Skin flare-ups

• Reflux

They’re still very real — and can be life-altering — but they don’t typically cause anaphylaxis.

In perimenopause, many women experience both: increased allergic reactivity and reduced tolerance to certain foods and drinks.

The Hormone–Histamine Connection

One of the key players here is histamine — a chemical involved in immune responses, digestion, and brain function. It’s also central to many allergy symptoms.

What’s less well known is that oestrogen and histamine have a two-way relationship:

• Oestrogen can stimulate mast cells (immune cells) to release more histamine

• Histamine can, in turn, stimulate the ovaries to produce more oestrogen

In perimenopause, oestrogen doesn’t just decline — it fluctuates wildly. These hormonal surges and dips can make mast cells more reactive and histamine responses more intense.

For me, tracking symptoms alongside my cycle made something very clear:

Where I am hormonally has a huge impact on how reactive my body is.

Certain points in my cycle now mean:

• Foods I usually tolerate may suddenly cause symptoms

• Alcohol hits much harder and triggers flushing, palpitations, or headaches

• Environmental allergens feel amplified

• Skin, gut, and sinuses all become more reactive

This isn’t imagined. Research increasingly shows links between hormonal shifts and mast cell activity, especially in women with histamine intolerance or mast cell activation-type conditions.

Why Midlife Can Lower Your “Tolerance Bucket”

Think of your body’s ability to cope with triggers as a bucket. When the bucket overflows, symptoms appear.

In your 40s, several things may be filling that bucket faster:

1. Hormonal Fluctuations

As mentioned, changing oestrogen and progesterone levels can directly influence immune responses and histamine release.

2. Gut Changes

The gut plays a huge role in both immunity and histamine breakdown. Over time, factors like stress, medications, infections, and diet can affect:

• Gut barrier integrity

• Microbiome balance

• Production of DAO (diamine oxidase), the main enzyme that breaks down histamine from food

If DAO activity is reduced, histamine from foods like aged cheeses, wine, fermented foods, and leftovers can build up more easily.

3. Cumulative Environmental Load

Years of exposure to pollution, chemicals, fragrances, mould, and allergens can gradually increase immune sensitivity in some people.

4. Stress and Nervous System Load

Chronic stress can make mast cells more reactive and worsen both allergic and intolerance symptoms. Perimenopause itself is often a high-stress life stage — physically and emotionally.

Alcohol: The Midlife Game-Changer

Many women notice alcohol becomes much harder to tolerate in their 40s.

That’s not just lower resilience — alcohol:

• Directly triggers histamine release

• Blocks DAO (so histamine isn’t broken down as well)

• Increases gut permeability

• Disrupts blood sugar and sleep, which can worsen overall reactivity

For those of us already dealing with histamine issues, alcohol can be the match that lights the fire.

Tracking Patterns: Knowledge Is Power

One of the most useful tools for me has been tracking symptoms alongside my cycle, food intake, stress, and environment.

Patterns started to emerge:

• Certain weeks = higher reactivity

• Some foods only cause issues when my “histamine bucket” is already full

• Environmental triggers matter more at specific hormonal points

This kind of tracking doesn’t replace medical care, but it can be incredibly empowering when working with allergy specialists and nutrition professionals.

Living With It — and Working With It

Being under the care of an allergy clinic and carrying emergency medication is now part of my normal. That can feel scary at first, but it’s also incredibly reassuring to have support and a plan.

At the same time, my background as a nutritionist and my master’s-level studies in clinical nutrition — with a focus on women’s health from perimenopause to post-menopause — have helped me approach this with curiosity rather than just fear.

This experience has deepened my understanding of:

• Histamine intolerance and mast cell responses

• The hormone–immune connection

• How nutrition, gut health, and lifestyle influence symptom load

And most importantly, it’s strengthened my empathy for clients who feel like their bodies have suddenly become “unpredictable” in their 40s. You’re not imagining it. And you’re definitely not alone.

The Takeaway

If you’ve developed new allergies or food intolerances in your 40s:

• You’re not alone

• Hormonal changes may be playing a significant role

• Symptoms can fluctuate across your cycle

• Professional assessment is essential, especially for any severe or systemic reactions

Perimenopause isn’t just about hot flushes and mood changes. For some of us, it’s also an immune and inflammatory shift that asks us to listen to our bodies in a whole new way.

And while it can feel frustrating — even frightening — it can also be a powerful turning point toward deeper understanding, better support, and more compassionate self-care.

I can honestly say that it has and is forcing me to be more focused on my own health and listening to my body.