28. Hay Fever | A Case Of Mistaken Identity

In this episode of Mohivate, Dr Mohi Sarawgee explores hay fever through the lens of immunology, bringing clarity to one of the most common and often underestimated conditions worldwide.
Hay fever, or allergic rhinitis, is an immune response shaped by genetics, environment, and a system designed to protect you, reacting to something that was never meant to be a threat.
Beneath the sneezing and the itchy eyes is a story about your immune system making a spectacular case of mistaken identity.
This episode covers how sensitisation works, the three overlapping pollen seasons, the hidden food connection most people never realise, the relationship between hay fever and asthma, and why hay fever is getting worse globally, and what that means for the hundreds of millions of people living with it.
Practical, clinically grounded, and with some tips that may genuinely change how you manage this season.

References:

1. Global prevalence of allergic rhinitis: 
Allergic Rhinitis: A Clinical and Pathophysiological Overview. Frontiers in Medicine, 2022.
https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.874114/full
2. Pollen seasons lengthening. Anthropogenic climate change is worsening North American pollen seasons. Proceedings of the National Academy of Sciences, 2021.
https://www.pnas.org/doi/10.1073/pnas.2013284118
3. UK pollen season. Climate Central — Pollen Season and Climate Change.
https://www.climatecentral.org/climate-matters/pollen-season-climate-change
4. United airway disease : hay fever and asthma connection. United Airway Disease: Current Perspectives. Journal of Asthma and Allergy, PMC.
https://pmc.ncbi.nlm.nih.gov/articles/PMC4872272/
5. Oral Allergy Syndrome. Stanford Health Care.
https://stanfordhealthcare.org/content/dam/SHC/clinics/menlo-medical-clinic/docs/Allergy/Oral%20Allergy%20Syndrome.pdf

Just a gentle reminder: this episode is for information, education, and inspiration only. It’s not a substitute for your doctor’s advice. For any personal health concerns, always seek guidance from your doctor.

Transcript

SPEAKER_00 0:04

Hi everyone, welcome back to Mohivate. I'm Dr. Mohi Saraugi, a GP by profession, but here I'm swapping prescriptions for perspective. We are officially in spring. For those of us in the Northern Hemisphere, the days are getting longer. The light is shifting, arriving earlier, staying a little longer each evening. And something inside us, something older than memory, recognizes it instantly. Like a curtain softly being drawn open. That deep biological knowing that the dark months are behind us. And then you step outside. It is absolutely freezing. Because this year the sun is beginning to come out. The calendar says spring, and the temperature is doing its own independent research. No collaboration. And we are still out here in our courts in April. Spring is here though, and for roughly 400 million people worldwide, it comes with a nose that runs at exactly the wrong moment. Itchy eyes that refuse to stop. Sneezing, not once, not twice, but in full sequences. In meetings, at Easter lunch, during that very important conversation you were trying to have. And a fatigue that only you understand. This week on Mohivate, let's discuss hay fever, the real version. Because beneath the sneezing and the itchy eyes is a story about your immune system, one of the most sophisticated defense systems in the known universe, making a spectacular case of mistaken identity. So let's understand the science behind hay fever and some practical tips that starting today, I truly hope will give you genuine relief. So let's begin. Let's start with the name because hay fever is genuinely one of medicine's stranger legacies. There is no fever in hay fever, and most people with it are not allergic to hay. The term dates to 19th century England when the condition was first described in patients who develop symptoms during the hay cutting season in summer, which yes is not spring, but the name arrived before the science did. The fever did not refer to elevated temperature but to a general state of unwellness. A fever in the medical language of the time simply meant illness. The name stuck. The accuracy did not. The correct medical term is allergic rhinitis. Rhinitis from the Greek rhinos meaning nose and itis meaning inflammation. In medicine, we have a habit of adding itis to things. It simply means inflammation preceded by the area it is affecting. Appendicitis, tonsillitis, dermatitis, and in hay fever specifically, allergic rhinitis, inflammation of the nose triggered by an allergen. Although for many sufferers, it feels less like allergic rhinitis and considerably more like pollinitis, inflammation of everything. It affects approximately 10 to 30% of adults worldwide and up to 40% of children. In the UK, roughly 1 in 4 people are affected. In the US, similar numbers. It is one of the most common chronic conditions on earth and in clinical practice, one of the most consistently and unnecessarily suffered through. And it is getting worse, which we will come to. To understand hay fever, we first need to briefly understand how the immune system works because hay fever at its core is a disease of the immune system. The nose is just where the story unfolds. Think of your immune system as the most sophisticated border security agency in the known universe. Its entire job is to scan everything entering your body through your nose, your eyes, your mouth, your skin, and decide friend or threat. If it is a genuine threat, a virus, a bacterium, a parasite, it mobilizes, it fights, it protects you. In people with hay fever, however, something has gone wrong with the training program. At some point, often in childhood, sometimes later, the immune system encountered a completely harmless pollen grain and filed it under dangerous. It created a specific antibody against it called IgE, immunoglobulin E, and positioned these IgE antibodies on immune cells called mast cells, which live in your eyes, your nose, your throat, and your lungs. Waiting. This is called sensitization and it happens silently. You feel nothing. The first time you encounter pollen, nothing visible happens at all. Then, the following pollen season, pollen enters your nose again. The Ig recognizes it instantly as a threat. And the mast cells which have been waiting, primed, ready, release a cascade of pre-stored inflammatory chemicals. Leucotrides, prostaglandins, cytokines, and the most famous, the one most implicated in allergic rhinitis, histamine. And this is where it gets vivid. Histamine causes blood vessels to dilate and leak fluid. That is your swelling and congestion. It stimulates nerve endings. That is the itch. It triggers mucus production. That is the sneezing and the runny nose. It makes your eyes water. It makes your throat scratch. It makes you, frankly, miserable. And here's what I want you to understand. Your immune system in this moment is not failing. It is succeeding exactly as trained. It has identified what it believes is a threat and responded with everything it has. It has just been given the wrong briefing. That is hay fever. The fundamental absurdity and the biological brilliance of allergic rhinitis. Your immune system produces five types of immunoglobulins IgA, IgD, IgE, IgG, and IgM, each with a different job. IgG fights bacteria. IgA protects mucosal surfaces. And IgE, the one that concerns us today, was designed in evolutionary terms to deal with parasites, worms, helmets, things that invade and burrow and need to be expelled rapidly. The Ig response is fast, powerful, and inflammatory, built to create an environment that parasites simply cannot survive in. In much of the developed world today, where parasite infections are rare, IgE has been left without its original job and it has somewhat catastrophically found a new one: attacking pollen, one of the most sophisticated defense systems in the known universe, brought to its knees by trees and grass. Most people think of hay fever as one season, one problem. I try to explain it differently. Hay fever is actually three overlapping seasons, and knowing which one affects you is both interesting and clinically life-changing. Season 1, tree pollen. Roughly February through May in the northern hemisphere. The main culprits birch, oak, ash, hazel, and plain trees. Birch is the biggest offender, one of the most allergenic trees globally. If your symptoms start in late winter, peak in April, and everyone around you is saying it is too early for hay fever, tree pollen is your trigger. It is never too early for tree pollen. Season 2, grass pollen, roughly May through August. This is the most common allergen globally. Timothy grass, ryegrass, Bermuda grass. The culprits vary by region, but the misery is universal. If June and July are your worst months, this is your season. Approximately 95% of hay fever sufferers in the UK are sensitized to grass pollen. It is also the season that worsens dramatically with climate change. Longer summers, higher temperatures, more pollen for longer. Season 3, weed pollen, roughly August through October. And yes, weed, the botanical kind. I should clarify. I'll leave the other interpretation entirely to you. Nettles, mugwort, ragweed. Ragweed, one plant produces up to 1 billion pollen grains per season and is one of the most potent allergens in the world. In Europe, nettle and mugwort are the main culprits. In the US, ragweed affects approximately 75% of hay fever sufferers and peaks in late summer and autumn. In India and parts of South Asia, East Africa and Australia, Parthenium and invasive weed introduced accidentally through wheat imports in the 1950s has become a significant allergen. Some people are sensitized to all three seasons, which means, and I say this with enormous clinical sympathy, they essentially have hay fever from February to October. If that is you, please know that immunotherapy exists. It works and we will come to it. Let's go through the symptoms because each one has an explanation. The sneeze is your body attempting to physically expel the allergen. The trigeminal nerve, one of the most powerful sensory nerves in the face, is stimulated by histamine and triggers the sneeze reflex. A single sneeze can expel air at up to 100 miles per hour. Now there are certain people in this world who find a loud sneeze deeply bothersome. I know this because two of them are in my family. This finding is dedicated to my mother and her niece, my cousin, who every time someone sneezes with any conviction whatsoever, respond as though a small explosion has occurred in the room. If you know someone exactly like this, you now have a scientific explanation to offer them. The person sneezing is expelling air at the speed of a motorway. It is involuntary. And now, finally, we have a citation. The runny nose, rhinoria, is mucus production driven by histamine stimulating goblet cells in the nasal lining. More mucus produce faster to wash the allergen away. The blog nose is paradoxically different. It is caused by vasodilation. Blood vessels in the nasal passages widen and leak fluid into the surrounding tissue, causing swelling and congestion. This is why antihistamines work well for sneezing and a runny nose, but often less well for blockage. Congestion is driven more by leucotrides and prostaglandins than by histamine alone, which is why nasal steroid sprays targeting the broader inflammatory response often work better for a blogg nose. The itchy eyes, allergic conjunctivitis, occur because the conjunctiva, the membrane lining the eye, also contains mast cells. Pollen landing on the eye surface triggers the same IgE-mediated response. The itch is histamine stimulating sensory nerve endings. And finally, the fatigue, the symptom most people least attribute to hay fever. The immune response itself consumes energy. Your body is running a continuous low-grade immune activation throughout the entire pollen season. The tiredness and the brain fog are not imaginary. One of the most fascinating and often unrecognized aspects of hay fever is something many people experience without realizing what it is. Do you ever notice an itchy mouth or a tingling throat when eating certain raw fruits or vegetables? Raw apples, peaches, cherries. If you're prone to hay fever, particularly to tree pollen, this is usually not a separate food allergy. It is called pollen food allergy syndrome, also known as oral allergy syndrome. The reason is cross-reactivity. Proteins in certain raw fruits and vegetables have a similar structure to pollen proteins. I.g. antibodies designed to recognize birch or grass pollen mistakenly react to these foods as the immune system sees a threat. Mars cells in the mouth release histamine. You get itching or tingling within minutes. Birch pollen allergy in particular is associated with reactions to foods such as apples, pears, cherries, plums, peaches, kiwi, carrots, celery, hazelnuts, and even almonds. Foods you may have never connected to your hay fever. Up to 70% of people with pollen allergy experience this to some degree, yet many are completely unaware of what it is. The remarkable thing, cooking almost always eliminates the reaction. The proteins are heat sensitive. They change structure when heated and the immune system no longer recognizes them. The person who cannot eat a raw apple may be perfectly fine with apple pie. Peeling fruit also removes much of the allergenic protein. Many people find they can tolerate peeled apples or pears without any reaction. And treating the underlying pollen allergy itself, which we will come to, addresses the root cause rather than the food reaction. Most reactions are mild and confined to the mouth and throat, resolving within minutes. If your symptoms extend beyond the mouth or involve swelling of the throat, please seek medical advice. Knowing what this is removes a significant amount of unnecessary anxiety and avoidance around eating. Sometimes you do not have to give up fruit. You may just need to cook it or peel it. A quick clinical point the relationship between hay fever and asthma. The nose and the lungs are the beginning and the end of one continuous airway lined by the same mucosa, regulated by the same immune mechanisms, and linked by shared inflammatory signals. In clinical medicine, we call this the united airway concept. One airway, one disease. Approximately 40% of people with hay fever also have asthma in varying degrees of severity. And in people with both conditions, poorly controlled hay fever significantly worsens asthma control. Nasal inflammation triggers a reflex that increases airway reactivity in the lungs. Post-nasal drip, mucus trickling from the back of the nose into the airway directly irritates the bronchi. If you have asthma and it seems harder to control in spring or summer, it is worth considering whether hay fever may be a contributing factor. Treating your hay fever more effectively may improve your asthma control significantly. Sometimes more than adjusting your inhaler alone. If your asthma seems inexplicably worse every May, it is worth discussing with your GP. Now let's understand why hay fever is getting worse every decade, everywhere. Three reasons. First, climate change. Across North America, pollen seasons now start around 20 days earlier than in 1990 and contains 21% more pollen. In the UK, the pollen season has extended by an average of 20 days since 1994. Across Europe, research spanning 12 countries shows the same pattern. Pollen seasons are getting longer almost everywhere. Higher carbon dioxide levels stimulate plants to produce more pollen, and emerging evidence suggests that pollen is becoming more allergenic, not just more abundant. More pollen, stronger pollen for longer. Second, urbanization, air pollution, particularly diesel particles, damage the lining of the nose and make it more permeable to allergens. Rates of hay fever are consistently higher in cities than in rural areas. The environment we have built is part of the problem. Third, the hygiene hypothesis. Children today are exposed to fewer microbes, fewer infections, and a less diverse range of environmental stimuli than any previous generation. The IgE arm of the immune system, originally designed to fight parasites, has, in the absence of those original targets, redirected itself toward harmless proteins, pollen, dust, food. Research suggests the immune system needs varied early exposure to develop balance. And when that balance is disrupted, it can become overly reactive. We have made our world so clean that our immune systems have declared spring an emergency. Now, what actually helps? The tools exist. Antihistamines are usually the first step, and the key word is before. Start them before your season begins, not when you are already sneezing. Two weeks before your typical season, if you can, consistently every day. The commonly used options are ceterizine, loratidine, and phegsophenidine, all available over the counter. Worth knowing from clinical practice, despite being classified as non-sedating, cetyrazine and phegzophenidine tend to be most commonly reported to cause drowsiness in some people. If that is you, try taking them at night or speak to your GP about which suits you best. There's no one size fits all. Then nasal steroid sprays, fluticazone, mometazone, budesonide are, in my view, the most underused and most effective treatment for hay fever. They work on the broader inflammatory cascade, not just histamine, which is why they work particularly well for congestion. Start them before your season, use them every day, even on good days. They take several days to reach full effect and most people stop too soon. If your eyes are your main struggle and oral antihistamines are not enough, antihistamine eye drops such as acylastine and lubricating drops such as sodium hyaluronate are both available over the counter and worth trying. For severe, persistent hay fever not controlled by these measures, allergen immunotherapy exists and it works. It involves gradually introducing the immune system to the allergen to recalibrate the immune response through injections or sublingual drops or tablets. It is available through specialist allergy services and worth raising with your GP if your symptoms are significantly affecting your quality of life. And some things I always mention that people find genuinely useful. Number one, Vaseline, a thin layer around the nostrils and on the nasal bridge traps pollen before it enters the nasal passage. The plain blue and white one, not the rosy lips. Simple, inexpensive, and surprisingly effective. Number two, sunglasses outdoors, wraparound sides if possible, a physical barrier between your eyes and airborne pollen. Number three, wash your hair when you come in on high pollen days because it accumulates in hair and continues affecting you through the evening. A quick shower makes a real difference. Number four, check the pollen forecast. High pollen counts are typically worst or On warm, dry, windy days, particularly in the afternoon and evening. On those days, keep windows closed and avoid drying clothes outside. They trap pollen and bring it straight into your home. Rain washes pollen from the air, and overcast cool days bring relative relief. And finally, if you wear contact lenses, switch to glasses on high pollen days. Contacts trap pollen directly against the cornea and significantly worsen eye symptoms. None of these replace treatment, but all of them help, and sometimes the smallest changes done consistently give you your spring back. So here we are. And behind every one of those symptoms, one of the most extraordinary immune stories in medicine. A defense system so sophisticated it can recognize a single pollen grain. So precise it remembers it the following year. So committed that it fights for you every single day, even when it has a wrong enemy. That immune system is yours and understanding it even a little changes everything. I hope you're able to step outside this week and feel the light of the season. To everyone celebrating Easter this weekend, to those marking Passover, or to anyone simply grateful that spring is finally here. I wish you warmth, rest and kindness from others and from yourself. I hope something today stirred a thought, gave you a smile, or simply made you pause. Thank you for listening. I'm Dr. Mohi. Until next time, remember, even when it feels inconvenient, your body is still trying to care for you. And learning what truly needs your response and what never did is where you continue to come home to yourself.