The most abundant pollen in the fall comes from ragweed, a plant that grows wild mainly in the Midwest and on the East Coast. Its highest levels are seen in early to mid-September, but the weed can bloom and release pollen any time from August to November.

Pollen is not the only allergen that can cause problems.

• Mold, while physically small, is also a significant contributor. Outdoor mold tends to be the most prevalent, but it can be easily tracked inside and cause allergic reactions indoors.
• Alternaria, showing up during the peak of summer into the fall season, is a fungus. It produces spores that can cause a variety of allergy symptoms and can trigger asthma attacks.

Produce is another hidden source of allergen exposure. Some fruits and vegetables can confuse your body into thinking they are allergens, triggering a local allergic reaction in your mouth.

"If you're allergic to ragweed, your body will make the 'anti-ragweed antibody,'" explains Cheryl A. Steiman, MD, a Northwestern Medicine allergist and immunologist who treats both pediatric and adult patients for seasonal, environmental, food and medicine allergies. "Though this protein binds to the ragweed allergen, fresh fruits and vegetables may resemble ragweed in the eyes of the protein."

That means that if you are allergic to ragweed, eating popular fall produce like cantaloupe, zucchini and watermelon may trigger an allergic reaction in your mouth. This is known as oral allergy syndrome. Symptoms can include an itchy mouth, scratchy throat and even swelling of the lips. Dr. Steiman compares this reaction to a "computer glitch" in the human body.

Symptoms of Fall Allergies

For other fall allergies triggered by pollen, mold, dust and dander, Dr. Steiman says that nasal congestion, runny nose and sneezing are the most common symptoms. Some people with seasonal allergies may also have eye irritation.
"Allergies are basically just a prolonged cold that predictably happens during the allergy season," explains Dr. Steiman. "Clear drainage is associated with allergies, while green and thick drainage would more likely be coming from an infectious process."

Allergy Testing and Treatment

Limiting your exposure to allergens can be challenging. When you start to notice symptoms, close windows and be sure to rinse off in the shower after spending time outside.

If you have more severe symptoms, over-the-counter or prescription medication, under the advice of your primary care physician, may help. Options include pills in the form of antihistamines or receptor blockers, as well as nasal sprays and eye drops.

If your symptoms are not improving under your primary care physician's current treatment plan, it may be time to see an allergy specialist. A specialist can perform a skin test to pinpoint your allergy triggers in order to develop a more personalized treatment plan.

Following testing, your physician might recommend allergy shots as an alternative to your current medications. Allergy shots are a way to train your body to tolerate the things you are allergic to. However, this treatment takes commitment. If you decide to have allergy shots, typically you will start out with weekly injections, then move on to monthly injections for three to five years, says Dr. Steiman.