Some people find themselves retreating indoors in late August, not because of the heat and humidity but because of their allergies. In the Northeast, South and Midwest, ragweed begins blooming in mid-August and continues to bloom until late October and sometimes longer, leaving ragweed allergy sufferers unable to enjoy the fall season.
A Hearty Weed
Ragweed, like other fall allergens such as sage, mugwort and rabbit brush, is a weed pollen that usually grows in areas that have not been developed, such as in fields, along roadsides and in abandoned lots. The billions of pollen grains that a single ragweed plant produces can travel through the air for up to 400 miles, so it’s found in urban, suburban and rural environments.
“Ragweed is incredibly hearty,” says Christopher Randolph, MD, an associate professor of allergy and immunology at Yale University School of Medicine and a spokesperson for the American Academy of Allergy, Asthma and Immunology (AAAAI). “It can be borne for miles into air and is found at sea and on every continent.”
When someone who is allergic to ragweed encounters this pollen, their immune system reacts in a number of ways. The body’s white blood cells produce IgE antibodies, which attach themselves to mast cells and trigger the release of histamine and other chemicals. Histamine swells the mucous membranes lining the nose and causes allergic rhinitis symptoms, such as sneezing, an itchy, runny nose and itchy, red eyes. Such symptoms can lead to fatigue, trouble concentrating and missed days of work or school.
Unlike what are known as perennial, or continuous, allergens, such as dust mites, molds, cockroach droppings and dog and cat allergens, ragweed and other seasonal, or intermittent, allergens tend not to cause asthma symptoms. “Animal allergens, for example, are very small, which means they can get deep in the airway and trigger asthma,” Dr. Randolph explains. “Pollens don’t get much below the windpipe, so they cause nasal symptoms.”
Some people with ragweed allergies also have allergies year-round because they are allergic to the continuous indoor allergens. Others are allergic to all pollens, so they are also sensitive to spring tree allergies and summer grass allergies—and still others are allergic only to ragweed. People who are allergic to ragweed may notice that they develop itchiness around their mouth and in their throat when they eat melons and bananas. That’s because a protein in ragweed is similar to a protein in these fresh fruits; these individuals do not have the type of food allergy that can lead to life-threatening allergic reactions known as anaphylaxis.
While symptoms are often used to diagnose ragweed allergy in the primary care doctor’s office, a more accurate approach is a skin sensitivity test performed by board-certified allergists. In these tests, the skin is pricked with an extract of ragweed pollen. In people who are allergic to the allergen, the skin will become red and swollen.
While the peak pollen times are between 10 am and 4 pm, pollen counts vary from day to day. Hot, dry and windy days are often the worst for pollen and, in general, pollen counts over 100 are considered high. According to Dr. Randolph, pollen counts can be useful, as long as they are specifically for the local area. “Most pollen counts reflect what’s going on over a 24-hour period, not what’s going on right now, so use it as a guide,” he says.
To minimize exposure to ragweed and other pollens, the AAAAI recommends that allergy sufferers stay indoors with the windows closed and the air conditioning running as much as possible. After spending time outdoors, it’s a good idea to shower to remove pollen that’s collected on your hair and skin.
If avoidance just isn’t doing the trick, people with ragweed allergies may need medication. Nasal sprays, including nasal antihistamines and nasal inhaled corticosteroids can reduce inflammation and ease nasal symptoms. Dr. Randolph cautions that certain over-the-counter decongestant nasal sprays can have a rebound effect because they do not block histamine, but constrict the blood vessels in the nose. After about a week, the nervous system rebounds and dilates the blood vessels, causing increased blood flow and congestion.
Likewise, patients with eye symptoms, also known as allergic conjunctivitis, should seek out prescription eye drops that block histamine or inhibit mast cells, rather than over-the-counter eye drops that just constrict the blood vessels in the eye to diminish redness. Dr. Randolph recommends refrigerating eye drops for extra relief. Other ways to ease itchy, red eyes include applying cold compresses and using artificial tears to wash away allergens from the eyes.
Over-the-counter and prescription oral antihistamines and decongestants treat multiple symptoms, though Dr. Randolph warns that non-sedating antihistamines are safest. People with chronic allergy symptoms who need antihistamines on a regular basis may be candidates for immunotherapy, or allergy shots. This treatment, which is prescribed by an allergist/immunologist, usually involves monthly shots that contain tiny amounts of the allergen for three to five years, during which time the body develops a tolerance to the allergen.
So those with ragweed allergies who are just trying to wait out the end of the season can take heart: With avoidance and treatment, you don’t have to sniffle your way from late summer to Thanksgiving.