By Mina Geris, BPharm (Otago) with Distinction, BBiomedSci (Otago), Integrative Natural Health Practitioner at Matakana Pharmacy & PracPharm
Every spring it starts again: itchy eyes, a blocked nose, and sneezing that just won't quit. For about one in five New Zealanders, hay fever isn't a minor nuisance. It disrupts sleep, makes it hard to concentrate, and drags down day-to-day life for months at a time.
So why does your body react so strongly to something as harmless as pollen? This guide walks through how common hay fever really is here, what histamine is actually doing inside your body, and why some Kiwis suffer while others sail through spring untouched.
How common is hay fever in New Zealand?
New Zealand has a real hay fever problem. Research from the University of Auckland puts it at roughly one in five New Zealanders affected. Associate Professor Amy Chan notes that at least a third of the population is likely to deal with hay fever or dust allergies, and once you count every type of allergy, somewhere between 30 and 40 percent of Kiwis experience an allergic condition of some kind.
The trend is heading the wrong way too. Allergy prevalence in New Zealand has climbed by around 50 percent over the past decade, mirroring what's happening globally. Our environment, lifestyle and climate seem to suit allergies far too well.
The quick numbers:
About 1 in 5 New Zealanders get hay fever.
30 to 40 percent of Kiwis have some form of allergy.
Allergy prevalence has risen roughly 50 percent in a decade.
Why is New Zealand so allergenic?
A lot of it comes down to geography and climate. New Zealand's pollen season is long, particularly from perennial rye grass, running from spring right through to Christmas. That means months of exposure rather than the few weeks people get in many other countries. Add our humidity and maritime climate, which suit mould spores and dust mites, and you have allergens around for much of the year.
There's an important link with asthma as well. Around 50 to 80 percent of people with asthma also get hay fever, and roughly a third of hay fever sufferers go on to develop asthma. That overlap is a good reminder that hay fever is a genuine respiratory condition, not just an annoying sniffle.
What is histamine, and what does it do in your body?
To make sense of hay fever, it helps to understand histamine. It's a chemical messenger your immune system uses, and in people with allergies it turns into the troublemaker of the whole story.
Where histamine comes from
Histamine is stored in specialised white blood cells: mast cells, found throughout your body in connective tissue, especially under the skin and near blood vessels, and basophils, which circulate in your bloodstream. When your immune system senses a threat, whether real or, in the case of allergies, imagined, these cells release histamine as a chemical signal.
Think of it as an alarm system. During a genuine infection or injury, histamine helps coordinate a useful immune response. In people with allergies, that alarm misfires and treats harmless pollen proteins as if they were dangerous invaders.
The allergic cascade: what histamine triggers
When you breathe in pollen and you're allergic to it, your body makes antibodies called IgE (immunoglobulin E). These bind to pollen proteins and attach to your mast cells. The next time that pollen shows up, histamine floods out of those cells and into surrounding tissue, latching onto receptors around the body and setting off the familiar symptoms:
Itching and sneezing. Histamine activates H1 receptors in the nose and throat, creating the itch that triggers sneezing as your body tries to clear the perceived threat.
Congestion and a runny nose. Histamine makes blood vessels in the nasal passages widen and become leaky. Fluid seeps into the surrounding tissue, causing swelling and stuffiness, while mucus production ramps up.
Red, watery eyes. The same thing happens in the delicate tissue around the eyes, leading to redness, itching and tearing.
Whole-body effects. In severe reactions, more widespread histamine release can cause throat swelling and trouble breathing. This is rare with seasonal allergies and far more common with food or insect-sting allergies.
This usually kicks off within minutes of exposure, which is why hay fever symptoms can appear so suddenly and so intensely.
Hay fever is more than a runny nose
It's easy to wave hay fever off as a minor complaint, but severe cases have a real impact on daily life. Poor sleep is common, whether that's trouble dropping off or staying asleep, and that flows into reduced concentration at work or study. Ongoing broken sleep can affect mood, immune function and how clearly you think.
There's a knock-on effect too. Inflammation and congestion in the sinuses and nasal passages can leave you more prone to secondary sinus and ear infections, which sometimes need antibiotics. For students sitting exams, professionals in a busy stretch, or anyone active who relies on clear breathing, the timing is rarely kind.
Common hay fever triggers in New Zealand
Knowing your own triggers is the first step to managing symptoms. Grass pollen is the biggest culprit here, but it's far from the only one:
Grass pollen, especially perennial rye grass, the main seasonal allergen.
Tree pollen such as birch, oak and elm, usually in early spring.
House dust mites, present year-round and worse in humid homes.
Mould spores, particularly in damp conditions.
Pet dander from cats and dogs.
Workplace irritants like chemicals, perfumes and other occupational exposures.
Some people have perennial allergic rhinitis, meaning year-round symptoms from indoor allergens, while others have seasonal allergic rhinitis set off by spring and summer pollen. Plenty of New Zealanders have both.
Why some people get hay fever and others don't
This is one of the questions we hear most: why does pollen set you off when your mate is completely fine? The answer sits somewhere between your genes and your environment.
Genetics. If your parents have allergies, you're more likely to develop them. Allergic conditions run in families, though not in a fixed way. You can have allergic parents and never get hay fever yourself.
Environment. The "hygiene hypothesis" suggests that growing up in very sanitised surroundings may prime a developing immune system to overreact to harmless things. Early childhood infections, by contrast, help train the immune system to tell real threats from harmless ones.
Timing. Hay fever often begins between the ages of 6 and 14, though it can start at any age, and some people find their symptoms ease or disappear later in life.
Level of exposure. Sensitivity can worsen with repeated exposure, or settle if exposure drops during key periods.
Managing hay fever: where to start
Understanding what's happening inside your body is genuinely the first step. What you're experiencing is a specific immune response driven by histamine, involving several body systems at once, not simply "being allergic to pollen".
From there, the good news is that effective management exists. Options range from reducing your exposure to allergens, through to antihistamines, nasal sprays and other symptom relief, plus supportive approaches that work on the underlying immune picture. If you'd like to browse what's available, you'll find our full range in Allergies, Hayfever & Sinus, and our Immune Support collection covers the wellbeing side of things. Everyone's triggers and history are different, so if you're not sure where to begin, you're welcome to book a complimentary consult with one of our practitioners or have a chat with the pharmacy team.
In our follow-up articles we'll dig into practical management in more detail, from small changes at home to over-the-counter and prescription options and newer approaches to building tolerance. For now, know that you're in good company: around a third of New Zealanders are right there with you, and this is very manageable.
Frequently asked questions
What is the main cause of hay fever in New Zealand?
Grass pollen, particularly from perennial rye grass, is the main trigger for hay fever in New Zealand. Tree pollen, house dust mites, mould spores and pet dander also play a part. Symptoms happen when the immune system reacts to these allergens and releases histamine.
Why is hay fever so bad in New Zealand?
New Zealand has an unusually long pollen season that runs from spring through to around Christmas, so exposure lasts for months rather than weeks. Our humid, maritime climate also suits dust mites and mould, which means allergens are around for much of the year.
What months are worst for hay fever in New Zealand?
Spring through early summer is generally the toughest stretch, as grass pollen builds from around September. Because rye grass pollen can persist into the warmer months, many people notice symptoms right through to Christmas.
Is hay fever an allergy or an infection?
Hay fever is an allergy, not an infection. It happens when the immune system mistakes harmless pollen for a threat and releases histamine, which causes sneezing, congestion and itchy, watery eyes. It is not contagious.
Can hay fever lead to asthma?
There is a strong link between the two. Around 50 to 80 percent of people with asthma also have hay fever, and roughly a third of hay fever sufferers go on to develop asthma. If you have hay fever and notice wheezing or breathlessness, it's worth speaking to your pharmacist or GP.
What causes hay fever symptoms like sneezing and itchy eyes?
Histamine. When you're allergic to something like pollen, your immune cells release histamine, which attaches to receptors in the nose, throat and eyes. That triggers itching, sneezing, congestion, a runny nose and red, watery eyes, usually within minutes of exposure.
References
University of Auckland. (2025). Will hay fever be better or worse this summer? Expert tips on hay fever with Amy Chan. auckland.ac.nz
Healthify. Hay fever. healthify.nz
Cleveland Clinic. What Is Histamine? my.clevelandclinic.org
White, M.V. (1990). The role of histamine in allergic diseases. Journal of Allergy and Clinical Immunology, 86(4), 599-605. pubmed.ncbi.nlm.nih.gov
NCBI Bookshelf. Biochemistry, Histamine. StatPearls. ncbi.nlm.nih.gov
New Zealand Herald. New Zealand's allergy epidemic. nzherald.co.nz
Allergy New Zealand. Allergic Rhinitis (Hay Fever). allergy.org.nz
About the author
Mina Geris is a New Zealand qualified pharmacist and integrative natural health practitioner with over a decade's experience across community and corporate pharmacy, and a special interest in functional medicine and integrative practice. Mina holds a BPharm (Otago) with Distinction and a BBiomedSci (Otago) in Functional Human Physiology, and is one of the senior practitioners at PracPharm.
This article is general information and not a substitute for personalised medical advice. If your symptoms are severe or persistent, please speak with your pharmacist or GP.
