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Ragweed Allergy

What Is It, Symptoms, Treatment, and More

Author: Ashley Mauldin, MSN, APRN, FNP-BC

Editors: Alyssa Haag, Józia McGowan, DO

Illustrator: Jillian Dunbar

Copyeditor: Joy Mapes


What is ragweed allergy?

Ragweed allergy refers to an adverse immune system reaction to ragweed plants. Ragweed is a type of weed that grows predominantly in the eastern and midwestern United States in the early fall months (August through November). When ragweed blooms, it produces pollen, a yellow, powdery substance that fertilizes other plants. Pollen counts, which measure the amount of airborne pollen in the area, are usually highest in the morning. Although most ragweed pollen falls near its plant of origin, ragweed pollen can travel up to 400 miles away. 

Ragweed allergy is one of the most common causes of seasonal allergies. Other common names for seasonal allergies are pollen allergy, hay fever, allergic rhinitis, and seasonal allergic rhinitis.

What causes ragweed allergy?

A ragweed allergy occurs when an individual’s immune system is sensitive to ragweed pollen. An allergic reaction, or allergy, is the body’s natural response to exposure to an allergen, or foreign substance. An individual may touch, inhale, or ingest an allergen. More rarely, exposure to an allergen may occur via injection. When an allergen, like ragweed pollen, enters the body of an individual who is sensitive to that substance, the immune system activates, and inflammatory chemicals, such as histamine, are released to help fight off the invader. These inflammatory chemicals can cause the characteristic symptoms of seasonal allergies (e.g., congestion, sneezing, runny nose). 

Predisposition to a ragweed allergy can be hereditary. If any family members are allergic to ragweed or other pollen, an individual is more likely to develop a specific allergy to ragweed.

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What are the signs and symptoms of ragweed allergy?

Ragweed allergy symptoms can include sneezing, mucus congestion in the throat and nose, and a runny nose. Individuals also commonly experience itchiness in the eyes, nose, and throat. 

Individuals allergic to ragweed might also have symptoms of oral allergy syndrome, or OAS. With OAS, the immune system can confuse ragweed pollen with certain foods, like watermelon, zucchini, cantaloupe, bananas, cucumbers, and honeydew. When these foods are eaten, the immune system will react and mount an immune response, which may result in itching or swelling of the mouth, throat, or face.

For those with severe allergies, or if symptoms are left untreated, asthma symptoms (e.g., coughing, wheezing, shortness of breath) can occur.

How common is ragweed allergy?

Ragweed allergy is fairly common in the United States, presenting in about 10-20% of the population.  Individuals allergic to ragweed are often allergic to additional types of pollen or have more allergies.

How is ragweed allergy diagnosed?

A clinician may be able to diagnose ragweed allergy after reviewing the individual’s medical history and conducting a physical examination. A referral to an allergist to perform allergy testing may also be recommended. Allergy testing usually includes skin sensitivity tests, which involve irritating or scratching the skin with potential allergens in order to assess the inflammatory response. If an individual’s skin turns red and itchy after being scratched with ragweed pollen, they have a ragweed allergy. Sometimes, blood tests are performed to check for the presence of ragweed antibodies. Antibodies are proteins the immune system produces in response to specific allergens in the body. If present, antibodies can indicate an allergy to a particular substance.

How is ragweed allergy treated?

There is currently no cure for a ragweed allergy; however, there are treatments that can help manage the symptoms. 

Preventive measures may be an option. An individual can limit exposure to sources of ragweed pollen by keeping all windows closed in both homes and cars, washing their hands after touching animals that have been outdoors, removing shoes and changing clothes after coming indoors, and showering before going to bed. Some individuals may also benefit from using a saline nasal spray, which can help flush allergens and mucus from the nasal cavity

Certain over-the-counter (OTC) medications are often recommended by healthcare professionals to help alleviate symptoms. A few commonly-recommended OTC antihistamines are loratadine (Claritin), fexofenadine (Allegra), and cetirizine (Zyrtec). Nasal steroid sprays, like fluticasone (Flonase), can alleviate inflammation in the nose and help reduce nasal congestion. It can be beneficial to start taking these medications before the onset of symptoms, especially before pollen counts rise during the peak of ragweed season. 

If over-the-counter medications do not provide enough symptom relief, or if symptoms persist for long periods of time, a prescription oral steroid, like prednisone, can be helpful. For persistent itchiness of the eyes, steroid eye drops, such as loteprednol (Alrex), may be prescribed. 

Over-the-counter decongestants, such as oxymetazoline (Afrin) or pseudoephedrine (Sudafed), can shrink swollen nasal passageways and may provide some relief, but they should be used only as directed, as they can be dangerous for individuals who have high blood pressure or heart problems. In addition, decongestant nasal sprays can make symptoms worse if used longer than a few days.

In cases of severe ragweed allergy or for long-term management, immunotherapy, whether in the form of sublingual tablets or allergy shots, may be necessary. For sublingual immunotherapy, the individual dissolves small tablets under their tongue. With allergy shots, the individual is injected with gradually increasing amounts of ragweed allergens. Both methods can help the body build tolerance to ragweed pollen and reduce the immune response, but it may take several months or years for immunotherapy to be effective. 

What are the most important facts to know about ragweed allergy?

When an individual comes into contact with a potential allergen, such as ragweed pollen, their body may see the foreign substance as harmful and activate the immune system. Ragweed allergy refers to an adverse immune system reaction to ragweed, one of the most common causes of seasonal allergies. Ragweed allergy symptoms can include sneezing, mucus congestion in the throat and nose, a runny nose, and itchy eyes, nose, and throat. Around 10-20% of individuals living in the United States have an allergy to ragweed. A clinician may be able to diagnose ragweed allergy after reviewing the individual’s medical history and conducting a physical examination. A referral to an allergist to perform allergy testing may also be recommended. There is no cure for ragweed allergy, so treatment is usually aimed at decreasing the symptoms. Certain medications, like antihistamines, as well as nasal, oral, and ocular steroids, may be recommended or prescribed by a healthcare professional to help alleviate symptoms. In cases of severe ragweed allergy or for long-term management, sublingual immunotherapy or allergy shots may be needed.

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Related links

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Resources for research and reference

American College of Allergy, Asthma & Immunology. (2019, March 21). Pollen food allergy syndrome. Retrieved April 7, 2021, from https://acaai.org/allergies/types/food-allergies/types-food-allergy/oral-allergy-syndrome

American College of Allergy, Asthma & Immunology. (2018, April 23). Ragweed allergy. Retrieved April 7, 2021, from https://acaai.org/allergies/types/ragweed-allergy

American College of Allergy, Asthma & Immunology. (2018, April 24). Sublingual immunotherapy (SLIT). Retrieved April 7, 2021, from https://acaai.org/allergies/allergy-treatment/allergy-immunotherapy/sublingual-immunotherapy-slit

Asthma and Allergy Foundation of America. (n.d.). Ragweed allergy. In Asthma and Allergy Foundation of America: New England Chapter. Retrieved April 7, 2021, from https://asthmaandallergies.org/asthma-allergies/ragweed-allergy/

Asthma and Allergy Foundation of America. (2019). Ragweed pollen allergy. Retrieved April 7, 2021, from https://www.aafa.org/ragweed-pollen/

Asthma and Allergy Foundation of America. (2015). Types of allergies. Retrieved April 7, 2021, from https://www.aafa.org/types-of-allergies/

Asthma and Allergy Foundation of America. (2015). What are the symptoms of asthma? Retrieved April 7, 2021, from https://www.aafa.org/asthma-symptoms/

Harvard Health Publishing. (2017, January 13). The secret to an easier allergy season. Retrieved June 8, 2021, from https://www.health.harvard.edu/allergies/the-secret-to-an-easier-allergy-season 

Smallwood, J. (2016). All about allergies. In KidsHealth from Nemours. Retrieved April 14, 2021, from https://kidshealth.org/en/parents/allergy.html