Published on October 21, 2018 at 14:41 / Updated on August 11, 2023 at 12:22

Many Quebecers are currently battling a major enemy: the Ambrosia plant. This annual plant, known as ragweed, provokes allergic reactions that cause considerable discomfort. Sneezing, nasal congestion, a runny nose, watery eyes, itchy skin and red eyes make up the daily routine of nearly one in 10 Quebecers from late July to late September. Year after year, the number of people affected continues to rise.

Where is ragweed found?

Ragweed is a plant that thrives in areas with little vegetation and heavy trampling. It is rarely found on well-maintained residential properties. Many municipalities are doubling down their efforts to mow the edges of bike paths, roads, parks and playgrounds. The media are also trying to better inform people about the need to remove these plants from residential, commercial, industrial and agricultural land. You don't need herbicides to get rid of this plant. Simple preventive measures are just as effective in stopping ragweed from growing or flowering.

How to recognize ragweed

Ragweed's appearance varies according to its stage of growth. In its vegetative stage, it can be recognized by its serrated foliage and hairy stem. At the flowering stage, you'll notice male flower spikes, responsible for the pollen that causes unpleasant allergic reactions. At maturity, it can reach up to 2 meters in height.

Ragweed or poison ivy?

Although their names are similar, their appearances and health consequences are very different. Poison ivy is a bush-shaped plant. Its leaves are composed of 3 pointed leaflets (small leaves). Its leaves are reddish in spring and turn green in summer.

When you touch poison ivy, it twill cause a severe skin reaction. On the other hand, there is no risk in touching ragweed. 

What causes ragweed?

It is the plant's pollen that is responsible of the allergic reactions. Pollen grains are very small, and their chemical characteristics mean that only a few grains are needed to trigger symptoms. Pollen travels through the air as a cloud of fine microscopic dust. Ragweed allergy is not in itself life-threatening. However, it is known that exposure to airborne allergens can trigger asthma attacks in susceptible individuals. In fact, many asthmatics also suffer from allergic rhinitis, a type of inflammation caused by an allergen. Note that not all allergy sufferers are necessarily asthmatics.

Ragweed pollen is not the only cause of allergic rhinitis. There are three periods of allergy to different pollens in Quebec. Trees and shrubs release their pollen in spring, while in summer it's the turn of different types of grasses. Ragweed releases its pollen from late summer to mid-autumn. Some people are allergic to all three types of pollen.

Cross-reactivity of allergens

Few people know that certain foods (e.g. melons, bananas, cucumbers) and plants (e.g. chamomile) contain proteins similar or identical to those in ragweed pollen. People allergic to ragweed who eat these raw foods may experience tingling reactions in the mouth, lips or throat. This phenomenon, called cross-reactivity, occurs when a person who normally reacts to an allergen comes into contact with a similar substance. The similarity between these proteins stimulates the allergy.

How can I avoid allergic reactions?

Pour les gens atteints, le meilleur moyen – mais pas nécessairement le plus facile - de prévenir les réactions allergiques est d’éviter d’entrer en contact avec les pollens. On recommande d’éviter les lieux infestés, de restreindre ses activités extérieures par temps chaud, sec et venteux, de ne pas tondre soi-même la pelouse, de ne pas faire sécher ses vêtements à l’extérieur pendant la période de libération du pollen, de laisser les fenêtres fermées ou d’utiliser un système de climatisation et d’éviter d’être exposé à la fumée de tabac, car elle peut amplifier les symptômes. Les efforts des municipalités et des citoyens pour éradiquer les plants sont naturellement les bienvenus.  Comme l’herbe à poux pousse difficilement dans les pelouses garnies, assurez-vous d’améliorer la qualité de votre sol, d’ensemencer votre gazon ou d’y planter d’autres végétaux. L’utilisation de paillis ou de couvre-sol aux endroits sans pelouse est aussi une bonne astuce.  L’arrachage et la tonte sont deux méthodes rapides et efficaces pour supprimer l’herbe à poux. Ne mettez pas les plantes arrachées ou tondues au compost, car les graines peuvent le contaminer. Mettez le tout aux ordures.

What to do if you suffer from allergies?

If, despite avoidance, you still experience allergy symptoms, a variety of medications are available from your pharmacy to help relieve them. With so many products to choose from, the advice of your pharmacist is often invaluable in making the right choice!

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