If your allergies feel worse than they used to, it’s probably not your imagination. Across North America, pollen seasons have become longer and heavier in recent decades, and climate change is a major reason.1PubMed Central. Anthropogenic climate change is worsening North American pollen seasons More people are breathing more pollen for more of the year, which makes the same allergy harder to live with. The right mix of medicine and home steps still controls symptoms for most people, and longer-term treatment exists when that isn’t enough.
Why Pollen Seasons Are Getting Worse
In North America, pollen season now starts about 20 days earlier than in 1990 and lasts about 8 days longer.2PubMed Central. Anthropogenic climate change is worsening North American pollen seasons Since 1990, a pollen season also contains about 21% more pollen, with tree pollen rising most.3Asthma and Allergy Foundation of America. 2023 Allergy Capitals Warmer days and warmer nights both lined up with heavier pollen loads.4PubMed. Temperature-related changes in airborne allergenic pollen abundance and seasonality across the northern hemisphere: a retrospective data analysis
For you, a longer season can mean symptoms in late winter, well before you think of it as allergy time. Tree, grass and weed seasons can overlap, so there’s no break between them. That is why starting treatment early in the season matters more than it used to.
Carbon dioxide plays a part too, because plants fed more of it make more pollen, and sometimes stronger pollen. Grass grown in the doubled carbon dioxide levels expected later this century made about 53% more pollen.5PubMed Central. Projected Carbon Dioxide to Increase Grass Pollen and Allergen Exposure Despite Higher Ozone Levels Oak trees grown in higher carbon dioxide made more pollen and more of the protein people react to.6PubMed Central. An Overview of Rising CO2 and Climatic Change on Aeroallergens and Allergic Diseases7PubMed. Effects of CO₂ on Acer negundo pollen fertility, protein content, allergenic properties, and carbohydrates Under a high-emissions future, US pollen season could start up to 40 days earlier and carry 16 to 40% more pollen.8PubMed Central. Projected climate-driven changes in pollen emission season length and magnitude over the continental United States
One rough year doesn’t mean your body changed, though. A warm spring can produce a heavy pollen year even if your allergy is exactly the same. Weather swings from year to year sit on top of the long-term climb, and checking local pollen counts helps you link your worst days to high pollen.
What Your Body Is Doing When Allergies Flare
After a first exposure, the body can make allergy antibodies called IgE that are tuned to one particular pollen.9PubMed. Pathogenesis of rhinitis On later exposure, pollen binds these antibodies on cells in the nose, which release histamine and cause sneezing and a runny nose within minutes.10PubMed. Pathogenesis of rhinitis Within hours, other immune cells move into the nose and keep it inflamed and blocked.11PubMed. Pathogenesis of rhinitis That second stage is why congestion can linger long after you come inside.
The two stages need different fixes. Antihistamines block the fast histamine stage well, but they do less for the stuffy nose of the slower stage. Treatments that calm inflammation cover both, which explains why one pill alone may not be enough.
Is It Allergies, a Cold, or Something Else
Itchy, watery eyes are common with allergies but not with colds or flu.12NIH News in Health. Cold, Flu, or Allergy? Duration is another clue: allergy symptoms last as long as you’re exposed, which can be about 6 weeks in a pollen season, while colds and flu rarely last beyond 2 weeks.13NIH News in Health. Cold, Flu, or Allergy?
A few other things help sort it out. Fever and body aches suggest flu, not allergies. Thick colored mucus with a fever can point toward infection, though colored mucus alone doesn’t prove it. Symptoms that return at the same time each year suggest pollen, while year-round symptoms that are worse indoors suggest dust mites or pets. If you have allergies, a cold can hit harder: allergic people showed much more sinus swelling during colds than people without allergies.14PubMed. Subjects with allergic rhinitis show signs of more severely impaired paranasal sinus functioning during viral colds than nonallergic subjects
See a doctor if symptoms don’t improve on over-the-counter treatment, or if you notice wheezing or chest tightness, which can signal asthma. Sinus pain with fever lasting more than about 10 days is another reason to get checked.
Medicines That Work Best
Nasal steroid sprays relieve congestion, itching, runny nose and sneezing.15PubMed. Intranasal corticosteroids for allergic rhinitis They also nearly completely prevent the slower, later-stage symptoms.16PubMed. Intranasal corticosteroids for allergic rhinitis That makes a steroid spray a good choice for stuffiness that pills don’t fix.
To get the most from one, use it every day, not only on bad days. The full effect takes several days to build, so starting a week or two before your season begins works best. Aim the nozzle slightly outward, away from the middle of the nose.
Antihistamines work by blocking the receptor that histamine acts on.17PubMed Central. H1 Antihistamines: Current Status and Future Directions Older ones such as diphenhydramine reach the brain and can cause drowsiness and slow thinking and reactions.18PubMed Central. H1 Antihistamines: Current Status and Future Directions Newer, second-generation antihistamines such as cetirizine, loratadine and fexofenadine are pumped back out of the brain,19PubMed. Why are second-generation H1-antihistamines minimally sedating? so they cause much less drowsiness.
Decongestant sprays used for more than a few days can cause rebound stuffiness, so keep them to short-term use.
The treatments combine well. A steroid spray plus an antihistamine eye drop helps itchy eyes, and a non-drowsy pill can be added on high-pollen days. If you take other medicines, ask a pharmacist about interactions.
Cutting Pollen and Dust at Home
Regular saltwater nose rinses for up to 7 weeks improved nasal symptoms by about 28%, and people using them needed about 62% less allergy medicine.20PubMed Central. Nasal irrigation as an adjunctive treatment in allergic rhinitis: A systematic review and meta-analysis Use distilled, sterile or boiled-then-cooled water, never straight tap water. Lean over a sink, pour into the upper nostril, and let it drain out the other side. Rinse after time outdoors on high-pollen days, and clean the bottle after each use.
Air filters help modestly. They ease daytime and nighttime allergy symptoms a little, but they don’t cut medicine use.21Indoor Air. Effectiveness of Air Filters in Allergic Rhinitis: A Systematic Review and Meta‐Analysis A high-efficiency furnace filter rated MERV 12 or higher cleans the whole home better than a single purifier.22PubMed Central. Effectiveness of Air Filters and Air Cleaners in Allergic Respiratory Diseases: A Review of the Recent Literature (MERV is a standard scale of how fine a particle a filter catches.) A HEPA purifier cleans only one room, so you need one in each room you use most.23PubMed Central. Effectiveness of Air Filters and Air Cleaners in Allergic Respiratory Diseases: A Review of the Recent Literature Ionic purifiers give little or no benefit and release ozone, which irritates the lungs.24PubMed Central. Effectiveness of Air Filters and Air Cleaners in Allergic Respiratory Diseases: A Review of the Recent Literature
To keep pollen out, close windows on high-count days. Shower and change clothes after time outdoors, and dry laundry indoors during pollen season. If you buy one HEPA purifier, put it in the bedroom first.
Indoors, dust mites are the other target. Their allergens come mostly from mite droppings and body fragments in bedding and furniture.25PubMed. The Role of Dust Mites in Allergy These particles can damage the nose’s lining and cause itching.26PubMed. The Role of Dust Mites in Allergy Zippered mite-proof covers on pillows and mattress help, as does washing bedding weekly in hot water. Fewer carpets and less clutter in the bedroom leave the mites less to live in.
Why City Life and Habits Can Make It Worse
Cities can be several degrees warmer than the surrounding countryside.27Asthma and Allergy Foundation of America. 2023 Allergy Capitals Ragweed pollen was up to seven times higher in a city about 3.6°F warmer with 30% more carbon dioxide than nearby rural land.28Asthma and Allergy Foundation of America. 2023 Allergy Capitals Planting pollen-making trees instead of fruiting ones adds to city pollen.29Asthma and Allergy Foundation of America. 2023 Allergy Capitals Pollution joins in as well: diesel exhaust combined with pollen switched on inflammation-related genes in airway cells in the lab.30PubMed. The priming effect of diesel exhaust on native pollen exposure at the air-liquid interface
In a city, avoid exercising beside busy roads on high-pollen days, and choose recirculated air in the car. Check both pollen and air-quality forecasts. In your own yard, fruiting or insect-pollinated trees release less airborne pollen, and a local nursery can suggest low-allergy choices.
Allergy Testing, Shots, and Tablets
Skin prick tests and blood tests for allergy antibodies usually agree well.31PubMed Central. Allergen-specific IgE: comparison between skin prick test and serum assay in real life Blood tests flag more people, though, including some who aren’t truly allergic.32Med J Malaysia. Comparison of Serum Specific IgE with skin Prick Test in the Diagnosis of Allergy in Malaysia A positive result needs to match your symptoms.
Allergy shots and under-the-tongue tablets give gradually rising doses of the allergen.33Otorhinolaryngology – Head & Neck Surgery. Understanding the Mechanism of Allergen Immunotherapy The body builds calming immune cells and fewer allergy-driving ones.34Otorhinolaryngology – Head & Neck Surgery. Understanding the Mechanism of Allergen Immunotherapy Later, it makes fewer allergy antibodies and more protective ones, which eases symptoms.35Otorhinolaryngology – Head & Neck Surgery. Understanding the Mechanism of Allergen Immunotherapy Tablets lead to lasting tolerance in a similar way.36Allergy. Sublingual allergen immunotherapy: mode of action and its relationship with the safety profile
In practice, shots start weekly and then space out to monthly. Treatment usually continues for three to five years. Tablets are taken daily at home after a first supervised dose. Benefits build over months, not days. It’s worth asking about if your symptoms persist despite medicine, if you want fewer daily medicines, or if you have allergic asthma alongside nasal allergies.
Itchy Mouth From Fruit and Other Pollen Links
Proteins in some foods closely resemble pollen proteins.37PubMed. Comprehensive review of pollen-food allergy syndrome: Pathogenesis, epidemiology, and treatment approaches Allergy antibodies in the mouth react to the food and cause local itching.38PubMed. Comprehensive review of pollen-food allergy syndrome: Pathogenesis, epidemiology, and treatment approaches Birch pollen often links with apples, cherries and carrots. Cooking usually breaks down the protein that causes the reaction, so cooked versions are often tolerated.
The reaction can feel stronger when pollen counts are high, and peeling fruit may help in some cases. Throat swelling or trouble breathing needs urgent care.
Allergies That Start or Change in Adulthood
Adult-onset allergies are most common in your 30s and 40s but can appear at any age.39Cleveland Clinic. Learning About Adult-Onset Allergies Allergies that start later in life tend to stick around.40Cleveland Clinic. Learning About Adult-Onset Allergies People with a long history of seasonal allergies, on the other hand, often have fewer symptoms as years pass, because the immune response tends to quiet in midlife.41Harvard Health. New allergies in adulthood
A new adult allergy might show up as sudden hay fever after a move to a new region, or as symptoms after getting a new pet or starting a new job. Getting tested can confirm the trigger.
How Allergies Affect Sleep and Mood
Allergy inflammation can disrupt sleep, which links allergies to low mood.42Pulmonology Advisor. Seasonal Allergies Often Accompanied by Mental Health and Sleep Disorders Poor sleep and inflammation feed each other and keep symptoms going.43PubMed Central. The relationship between allergic rhinitis and sleep disorders and mental health Stress and poor sleep also make it harder to cope and to stick with treatment.44PubMed Central. The relationship between allergic rhinitis and sleep disorders and mental health
Daytime tiredness often comes from blocked breathing at night, and fatigue often improves once congestion is controlled. To break the loop, treat nighttime congestion with a daily steroid spray and run a HEPA purifier in the bedroom. If your mood stays low, tell a doctor.