Seasonal Allergies (Hay Fever)

Symptoms

What happens in the body to cause allergy symptoms?

Allergies are an overreaction by the immune system to an otherwise usually harmless substance, causing the release of IgE antibodies. Upon repeat exposure, these antibodies act on mast cells, sparking the release of histamine and other inflammatory mediators.

Histamine is primarily responsible for the immediate itching and sneezing, whereas other molecules are tied to congestion, increased secretions, and other symptoms. Most allergies develop during early childhood, though some can also begin later in life.

Why do some people have seasonal allergies and others don’t?

Seasonal allergies have a strong genetic component, but their severity depends on a complicated set of environmental triggers that include initial intensity or dose of the allergen, age and immune status at time of exposure, and frequency of exposure.

Some other emerging risks that contribute to the rising worldwide prevalence of seasonal allergies include increased air pollution, decreased time spent outdoors in childhood, changes in the way buildings are ventilated, diets low in fresh food, and more caesarean section births. Reduced exposure to environmental microbes is another area that is receiving attention.

Are there other allergies or conditions that can make seasonal allergies worse?

Seasonal allergies can be more disruptive if someone has anatomic factors—like nasal polyps or a severely deviated septum—that predispose them to nasal congestion. Perennial allergies, like dust mite or animal dander allergies, can also amplify the immune response.

Can seasonal allergies increase the risk of other health problems? What are the implications of not managing them?

Children with allergic rhinitis are more predisposed to middle ear infections. Likewise, adults with allergies have an increased risk for sinus infections, likely due to stasis and poor clearance of mucus. And swollen upper airway tissue has implications for other breathing problems--like snoring, which can impair sleep.

More vague symptoms include fatigue, irritability, productivity loss, and impaired learning and decision making. Surprisingly, there is a higher rate of migraines in people with allergies, though there isn’t a clear causative role here.

Are there any associated patterns for people to look for with other sensitivities?

Atopy is the word we use to describe an allergic response in the body, and people with seasonal allergies have a higher incidence of other atopic conditions than the general population. Asthma, eczema (atopic dermatitis), and pollen-food allergy syndrome are some examples of atopic conditions.

Frequency

When are most people affected?

Geographic location determines specific timelines, but there are some generalizations. Tree and grass pollens are at their highest in the spring and summer, with tree pollination occurring before grass pollination, often as early as February. Ragweed, which is a plant with very broad distribution nationwide, is a common allergen in autumn, peaking for most of the country in September.

In addition to seasonal trends, pollen counts fluctuate throughout the day, ramping up in the morning and decreasing towards the evening. There are exceptions to that: Urban areas tend to have a delayed daily progression compared to rural areas.

Why are some years and locations worse than others?

Weather conditions dictate the yearly fluctuations, while dominant flora populations contribute to geographic variance. Temperature, precipitation, elevation, and latitude are all factors that affect pollination start dates and season lengths. The Southeastern and Southern states have the highest rates of hay fever in the US.

Have allergy patterns changed over the past decades in relation to climate change?

Seasonal allergies are increasing worldwide, as are other atopic diseases, and research is showing that climate change is one contributor. Observed and anticipated impacts include pollen season extensions and shifts due to warming temperatures and more ozone alert days in densely populated areas. Also of concern are the appearance of allergenic species in new climatic areas, damp housing due to rising sea levels, and increased wildfires.

Is it useful for people with allergies to pay attention to reported pollen counts or pollen maps?

Pollen counts and maps can certainly help people reduce exposure. They can be used to help with planning outdoor activities and deciding when to keep windows closed, for example.

Medications

What’s the best way to treat allergies?

The major categories of allergy medications are antihistamines (taken orally, as nasal sprays, or as eye drops), steroids (taken as nasal sprays or oral inhalers), mast cell stabilizers (taken orally, as nasal sprays, or as eye drops), and decongestants (taken orally or as a nasal spray). Most, but not all, of these medications are available over-the-counter.

Newer developments in allergy treatment often combine these different mechanisms into preparations that allow for easier dosing and longer duration of action. If the allergic response extends to the lungs—as they do in an asthmatic individual—we utilize oral inhalers, which require a prescription.

Are there any downsides to taking antihistamine medications for a prolonged time?

It’s useful to differentiate antihistamines into generations, which refers to when they were developed and also defines their pharmacologic actions and side effect profiles. The most common first-generation antihistamine still used is Benadryl (diphenhydramine).

What distinguishes first-generation antihistamines from later generation ones (Claritin, Allegra, Zyrtec) is that the former more easily penetrate the blood-brain barrier and have nervous system effects, including sedation and cognitive sluggishness. Sedation can be a useful side effect, especially at night, but there is some emerging concern about what happens over the long-term, especially when the newer generation meds are equally efficacious.

What do you think about the research that has linked first-generation antihistamines to a possible increased risk for dementia?

While there are some valid criticisms of the studies, in light of their results, I rarely prescribe first-generation antihistamines now, preferring to use therapies without those potential side effects. The newer generation antihistamines fit that bill. Many people use first-generation antihistamines for insomnia, and I think there are better ways of managing that.

What about other medications?

Intranasal corticosteroids (Flonase, Nasonex, etc.) have a long track record for safety and are considered to be the first line of treatment for persistent allergic rhinitis. Proper use is important, and includes spraying away from the septum in-between the nostrils.

Decongestant nasal sprays (Afrin, etc), for their part, have a unique side effect of causing physical habituation. In cases of congestion, they should not be used for more than three-to-four days, as abrupt cessation can induce a rebound of worsened congestion.

For allergic conjunctivitis (eye itching, redness, tearing), antihistamine eye drops are first-line pharmacotherapy, and are of greater benefit if begun two weeks prior to allergy season. Montelukast (Singulair) can be helpful for people who have both allergies and asthma, though it is also possible to add it to oral antihistamine therapy in those who do not tolerate nasal sprays. Pregnant women and children under two should use other alternatives.

Does it matter in terms of symptoms or treatment if someone is allergic to pollen versus grasses versus other environmental factors?

The allergic trigger doesn’t matter as much as the tissue response. Some people have more issues with their eyes, some with their nose, and others with the lower respiratory airways in the lungs. We can customize prevention and treatment based on this. For example, those who are primarily affected by sneezing and runny nose may receive more benefit from a nasal spray, which is considered first line treatment of allergic rhinitis (nasal symptoms).

Further Treatment

Who should receive allergy testing?

Most people with seasonal allergies do not need allergy testing. However, if symptoms are not adequately controlled by minimizing allergen exposure and medication, then testing is a worthwhile next step to consider, especially if immunotherapy is being considered.

What about allergy shots?

Long-term modification of the allergic response can be achieved by immunotherapy, via sublingual tablets (SLIT), or through allergy shots. Rather than suppressing symptoms directly, allergy shots alter the immune response over time, so that the body becomes less allergic through acquired tolerance. This approach is typically pursued by people who cannot achieve satisfactory resolution with medications alone—or who do not wish to take the usual medications regularly.  

Is there anything else people can do to decrease the severity of their allergic response or make it less likely for them to have allergies in the first place?

Prevention relies on avoidance of the allergen. Staying indoors with closed windows during peak pollen hours or on dry, windy days can help significantly, as can rinsing off the skin and washing hair at night to prevent further exposure during the evening.

Nasal saline and sinus rinsing help flush pollen from the respiratory epithelium, where it causes problems. Wearing sunglasses or choosing glasses instead of contacts on bad days is another strategy for preventing allergic conjunctivitis. Air purifiers, especially those labeled HEPA, help decrease circulating indoor pollutants and pollens. Lastly, caring for your airways by not smoking ensures proper movement and elimination of respiratory secretions.

Is there anything else people can do to treat allergy symptoms?

There are a variety of supplements that have analogous roles to pharmaceuticals. Stinging nettles in capsules or tincture form work by decreasing histamine release. Quercitin—a compound found in many foods--stabilizes mast cells, and is sometimes combined with stinging nettles. Butterbur is a plant that has mixed results in studies, trending toward efficacious, and (interestingly) is also used to prevent migraines. Also worth mentioning is acupuncture. Used for thousands of years to manage allergies, it has demonstrated efficacy in many studies.

Does diet matter with allergies?

Eating a diet rich in nuts, seeds, healthy oils, brightly-colored produce, and omega-3 fats can reduce overall inflammation in the body. This anti-inflammatory polyphenol-rich eating pattern shares considerable overlap with the Mediterranean diet. Some people have specific triggers that cause them more congestion or mucus production, but it is hard to generalize those triggers to broad populations.

Useful Links

Tips for proper use of nasal sprays (Family Doctor)

Home products to control allergies (Allergy Control)

A comprehensive resource center for allergy news and research (World Allergy Organization)

National allergy pollen maps and forecasts (Pollen.com)

Will every kid have allergic rhinitis soon? (International Journal of Pediatric Otorhinolaryngology)

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