What Is a Ragweed Allergy?
Ragweed plants are soft-stemmed weeds that grow all over the United States. There are at least 17 species of ragweed that grow in North America. The plants are most often found in rural areas and open spaces that get plenty of sunlight. Between the late spring and fall months, ragweed plants release tiny grains of pollen in order to fertilize other ragweed plants.
Depending on the location, ragweed may begin spreading its pollen as early as the last week of July and continue into the middle of October. Its wind-driven pollen can travel hundreds of miles and survive through a mild winter.
Ragweed pollen is one of the most common causes of seasonal allergies in the United States. Many people have an adverse immune response when they breathe in the pollen. Normally, the immune system defends the body against harmful invaders, such as viruses and bacteria, to ward off illnesses. In people with ragweed allergies, the immune system mistakes ragweed pollen as a dangerous substance. This causes the immune system to produce chemicals that fight against the pollen, even though it’s harmless. The reaction leads to a variety of irritating symptoms, such as sneezing, running nose, and itchy eyes.
Approximately of Americans have a ragweed allergy. The allergy is unlikely to go away once it has developed. However, symptoms can be treated with medications and allergy shots. Making certain lifestyle changes may also help relieve the symptoms associated with ragweed allergies.
What Are the Symptoms of a Ragweed Allergy?
Your symptoms may vary at different times of the year, depending on where you live and the weather. However, the most common ragweed allergy symptoms include:
- itchy, watery eyes
- scratchy throat
- runny nose or congestion
- coughing or wheezing
- sinus pressure, which may cause facial pain
- swollen, bluish-colored skin beneath the eyes
- decreased sense of smell or taste
- poor sleep quality
In some cases, people may also develop allergic eczema after being exposed to ragweed pollen. This itchy, painful rash is usually comprised of small bumps and blisters. It can appear within 24 to 48 hours after exposure. The rash will usually resolve on its own within two or three weeks.
Symptoms can become worse due to other irritants, such as tobacco smoke, strong odors, or air pollution. According to the , climate change may also be making ragweed allergy symptoms worse. Warmer temperatures may extend the ragweed pollen season. They can also cause ragweed to produce increased amounts of pollen.
What Causes a Ragweed Allergy?
A ragweed allergy occurs when the immune system has an inappropriate response to ragweed pollen. Normally, the immune system promotes chemical changes in the body that help fight off harmful invaders, such as viruses and bacteria. In people with ragweed allergies, however, the immune system mistakenly identifies the harmless pollen as a dangerous intruder and begins to fight against it. A natural substance called histamine is released when the body encounters ragweed pollen. The histamine causes many uncomfortable symptoms such as a runny nose, sneezing, and itchy eyes.
Ragweed belongs to a larger family of flowering plants called Compositae. These plants can be found in all 50 states as well as in many places in Canada and temperate regions of South America. Someone can come into contact with ragweed pollen simply by breathing in the air, which makes the pollen very difficult to avoid. Ragweed pollen season typically occurs between August and mid-October, and peaks in September. The amount of pollen in the air is usually highest between 10 a.m. and 3 p.m., depending on the weather. Rain and low temperatures can help lower pollen levels.
People who are allergic to other substances are more likely to be allergic to ragweed pollen. You’re at an increased risk for ragweed allergies if you’re also allergic to:
- dust mites
- pet dander
- other types of pollens, such as tree pollen
Allergies also tend to run in families, so if one of your close family members has a ragweed allergy, then you’re more likely to develop one too.
How Is a Ragweed Allergy Diagnosed?
Your doctor can usually diagnose a ragweed allergy. However, they may refer you to an allergist for allergy testing to confirm the diagnosis. An allergist is someone who specializes in diagnosing and treating allergies. The allergist will first ask you about your medical history and your symptoms, including when they started and how long they have persisted. Make sure to tell them if the symptoms are only present or get worse at certain times of the year.
The allergist will then perform a skin prick test to determine the specific allergen that’s causing your symptoms. The skin prick procedure typically goes as follows:
- The allergist marks a section of your arm or back with a pen or marker.
- They then place drops of various types of allergens in different areas on the skin.
- The spots of skin containing these drops are lightly pricked or scratched with a needle. This may be slightly painful or uncomfortable, but it only takes a few minutes to complete.
- If you’re allergic to any of the substances, you’ll develop redness, swelling, and itchiness at the site within 15 to 20 minutes. You might also see a raised, round area that looks like a hive.
- The allergist will go over the results with you. You might be allergic to more than one substance.
Having a reaction during a skin prick test doesn’t always mean that you’re allergic to the substance. The allergist will use the skin prick test results and their own medical evaluation to determine a diagnosis and a treatment plan.
How Is a Ragweed Allergy Treated?
Ragweed pollen is very difficult to avoid, so you’ll probably experience continuous allergic reactions. However, there are numerous different treatments that can help relieve ragweed allergy symptoms.
Medicines that can ease symptoms include:
- antihistamines, such as loratadine (Claritin) or diphenhydramine (Benadryl)
- decongestants, such as pseudoephedrine (Sudafed) or oxymetazoline (Afrin nasal spray)
- nasal corticosteroids, such as fluticasone (Flonase) or mometasone (Nasonex)
- medications that combine an antihistamine and decongestant, such as Actifed and Claritin-D
Ask your doctor about prescription drugs, such as montelukast (Singulair), if over-the-counter medications are ineffective.
Your doctor may recommend allergy shots if medications aren’t working. Allergy shots are a form of immunotherapy that involves a series of injections of the allergen. The amount of allergen in the shot gradually increases over time. The shots modify your body’s response to the allergen, helping to reduce the severity of your allergic reactions. You may experience complete relief within one to three years after starting allergy shots.
Sublingual immunotherapies for treating ragweed allergies are also available. This type of treatment involves placing a pill containing the allergen under the tongue and then swallowing it. It provides the same benefits as allergy shots.
You can also make certain lifestyle adjustments to help prevent an allergic reaction to ragweed:
- use an air conditioner for extended periods of time and well into the fall
- avoid going outside in the morning, which is when pollen counts are at their highest
- buy a portable high-efficiency particulate air (HEPA) filter or dehumidifier
- vacuum the house every week with a vacuum cleaner that has a HEPA filter
- immediately wash clothing items after wearing them outdoors, as they may have pollen on them
- dry clothes in a dryer rather than outside on a clothing line
Foods to Avoid
Some foods and herbs contain proteins similar to those in ragweed pollen, so they may trigger an allergic reaction. These include:
- honeydew melons
Symptoms related to food allergies will typically be worse during ragweed season. You should contact an allergist if you notice your mouth tingling or itching after eating any of the foods listed above.