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Ragweed Allergy: Symptoms, Causes, and Treatment

Ragweed Allergy: Symptoms, Causes, and Treatment

5 minute read time

The pollen from ragweed is notorious for causing allergy symptoms in many people, representing one of the most common triggers of seasonal allergies in the UK and US where it grows in 49 states. As a strong allergenic, ragweed pollen is a primary contributor to hayfever symptoms, or allergic rhinitis, which affects nearly 20% of people in the UK. In turn, this invasive weed has become a growing concern for human health throughout Europe as well.

As a wind-driven pollen, ragweed plants release tiny grains of pollen into the air to fertilise other ragweed plants. Not only does ragweed have a widespread presence in the UK and other parts of Europe and America, but there are several varieties of ragweed (e.g. Ambrosia artemisiifolia and Ambrosia trifida) that can grow to varying heights.

Depending on the region and climate, ragweed allergies are most prevalent between the end of June to September. However, the exact timing and peak of ragweed pollen release vary from year to year depending on weather conditions like wind, rainfall, and temperatures.

What is a Ragweed Allergy?

Ragweed pollen is characterised by its high potential to cause type I allergic reactions, also known as an immediate reaction involving immunoglobulin E (IgE) mediated release of antibodies1.

With a ragweed allergy, the immune system recognises the pollen as a dangerous substance and combats this perceived threat by releasing inflammatory chemicals that fight against the pollen, despite it being harmless. It’s the body’s immune system defenses that cause an irritating allergic reaction.

Allergy symptoms can range in severity and most commonly include sneezing, stuffy or runny nose, itchy eyes, and itchy throat.  Unfortunately, an allergy to ragweed is not likely to go away once it has developed. However, symptoms can be minimised with proper allergy treatment.

Ragweed Allergy Symptoms

Like most pollen allergies, there are many factors that can influence the symptoms of ragweed allergy and their severity. This includes the time of year, the weather conditions, and where you live. In general, the most common ragweed allergy symptoms include:

  • stuffy or runny nose
  • coughing or wheezing
  • scratchy throat
  • itchy, watery eyes
  • sinus pressure, which may cause facial pain
  • skin swelling beneath the eyes
  • weakened sense of taste or smell
  • poor sleep quality

Some symptoms can manifest as skin conditions, like an allergic eczema rash, within 24 to 48 hours after being exposed to ragweed pollen. This irritating skin condition is usually itchy and painful and has the appearance of small bumps and blisters.

Ragweed pollen can also aggravate respiratory problems and asthma symptoms, leading to increased coughing and wheezing. Other airborne irritants, such as exposure to air pollution and smoke, can make ragweed allergy symptoms worse.

Climate change may also be a proponent of increased ragweed allergy rates and worsened symptoms. In the US, for instance, the EPA warns that rising temperatures can extend the ragweed pollen season and cause ragweed to produce greater amounts of pollen. A study by the USDA confirmed this link between climate change and prolonged ragweed allergy seasons.

What Causes a Ragweed Allergy?

The biological mechanisms behind ragweed allergy are caused by the immune system and its ill-suited response to mistaking ragweed pollen as a foreign invader.

When normally exposed to viruses, bacteria, and other harmful threats, the immune system prompts chemical changes in the body to fight these intruders. In cases of ragweed allergy and other pollen allergies, the immune system triggers the same defensive response to fight against these otherwise harmless substances. As part of this immune system reaction, a natural substance called histamine is released, which causes irritable allergy symptoms like congestion, runny nose, sneezing, and itchy eyes and throat

You can be exposed to ragweed pollen simply by breathing in the air, which makes it very difficult to avoid the pollen when outdoors. Ragweed allergy season peaks during the summer months, and depending on the weather, the highest pollen count in the air is generally between 10 AM and 3 PM during the day. Dry conditions, warmer temperatures, and high winds can increase ragweed pollen levels and allergy susceptibility.

People who are sensitive to or allergic to other substances may be more prone to ragweed allergy symptoms. For instance, if you’re allergic to other types of pollen (such as tree pollen or grass pollen), mould, and dust mites, you may be at a greater risk of developing a ragweed allergy.

How to Diagnose a Ragweed Allergy

The best way to determine which pollens and substances are responsible for your allergy symptoms is to get tested. Your general physician can recommend the necessary procedures to help you pinpoint the type of pollen that you may be allergic to. There are also at-home test kits that make it easy to determine such sensitivities and allergies. These most common options to effectively diagnose a ragweed allergy are a blood test or a prick test.

  • Blood test: blood tests are one of the most common at-home testing methods to determine a pollen allergy. With such tests, a blood sample will be sent to an accredited laboratory to be analysed. Depending on the test, you’ll be notified which pollen you may be allergic to.
  • Prick test: With prick tests, your physician will inject a small dose of allergen under your skin. If your body triggers a minor allergic reaction, such as a rash, you can determine or rule out the type of pollen causing the allergy symptoms.

Once you can confidently recognise the type of pollen responsible for your allergy symptoms, you’ll be better able to identify the offending, pollen-producing plant and avoid conditions that may flare up your allergies.

Ragweed Allergy Treatment

Due to its widespread prevalence and long-lasting season, exposure to ragweed pollen can be an ongoing nuisance that’s difficult to avoid. Fortunately, there are several treatment options that can help relieve symptoms.

  • Medications: over-the-counter options like antihistamines, decongestants, nasal corticosteroids, or medications that combine these drugs can be highly effective in reducing ragweed allergy symptoms. Your physician may be able to prescribe an allergy medicine for ragweed if over-the-counter options are ineffective.
  • Allergy shots: when medications do not work, your physician may recommend allergy shots, usually in the form of a series of allergy-specific immunotherapy (AIS) injections. As one of the few treatments that provides long-lasting effects2, AIS is designed to adapt your body’s response to the allergen over time.
  • Lifestyle changes: certain lifestyle modifications can help prevent allergic reactions to ragweed. Pay close attention to the daily pollen count when planning outdoor activities. You can also invest in things like air conditioners, air filters, and dehumidifiers that help with filtration and minimising pollen exposure indoors.
  • Avoid certain foods: there are a number of foods and herbs that contain proteins similar to those in ragweed pollen, which can trigger an allergic reaction. Echinacea, chamomile, melon, cucumbers, bananas, and zucchini are a few of the most common to watch out for.

It is important to treat ragweed allergy symptoms as soon as they start occurring. If you neglect your allergy symptoms, they can lead to wider health problems like sinusitis, conjunctivitis, and other forms of respiratory illnesses.

The first line of defence is awareness and determining an allergy to ragweed or other types of pollen. An at-home test kit from yorktest is an easy and effective way to pinpoint a ragweed allergy as well as that of other types of foods and pollen.


1 Abbas M, Moussa M, Akel H. Type I Hypersensitivity Reaction. [Updated 2021 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560561/

2 Chen, Kuan-Wei et al. “Ragweed Pollen Allergy: Burden, Characteristics, and Management of an Imported Allergen Source in Europe.” International archives of allergy and immunology vol. 176,3-4 (2018): 163-180. doi:10.1159/000487997


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