Allergy to grasses

What Is Grass Allergy – Symptoms, Treatment And Prevention

Allergy to grasses is an abnormal and exaggerated reaction of the immune system , induced by the inhalation of pollen grains dispersed in the environment.This event occurs on a seasonal basis , occurring in the months of the year in which the flowering of the plant species to which it is susceptible occurs (e.g. bunchgrass, codolina, meadow grass, etc.), usually between March and September.
Allergy induced by grass pollen is characterized by the appearance of symptoms similar to those of a common cold , such as attacks of sneezing , redness and itching of the eyes , abundant nasal discharge and difficulty breathing .
The onset, intensity and duration of the symptoms depend mainly on variations in the concentration of pollen present in the atmosphere.
In addition to symptomatic therapy with antihistamine and corticosteroid drugs , there are various preparations for allergen immunotherapy , with optimal results especially if it is started early.

Pollen: What Are They?

  • Pollen are the male reproductive cells (gametophytes) produced by plants during flowering. These small and light grains have the task of fertilizing other plants of the same species.
  • Considering their small size, anemophilous (airborne) pollens are carried by the air even over long distances and can be easily inhaled, therefore they are able to penetrate the respiratory tract . Pollen contains particular substances, called antigens , capable of “sensitizing ” genetically predisposed subjects.
  • Allergens are released when the granule comes into contact with the moist surface of the respiratory tract. The pollens themselves have enzymatic activities that facilitate the penetration of allergens through the mucous membranes.


What Causes Grass Allergy?

At the basis of grass allergy there is a hypersensitivity reaction of the immune system, mediated by a particular class of antibodies : Immunoglobulins E (IgE). In predisposed subjects, this response is triggered by the inhalation of allergenic pollens to which they are sensitized (e.g. bunchgrass, codolina, meadow grass, etc.) during the flowering (or pollination) period.

Note : in the diagnostic phase, IgE can be searched for and measured in the patient’s serum to confirm allergic sensitization.

The immune system is activated by mistakenly identifying grass pollen as dangerous substances. The production of IgE stimulates the release of chemical mediators of inflammation: histamine , prostaglandins , leukotrienes , bradykinin and others. These substances act by causing an phlogistic process: they dilate the capillary vessels and attract particular defense cells from the blood and tissues, which participate in the reaction. The final result is the induction of the typical symptoms of grass allergy.
The presence of allergenic granules is influenced by the climate and the spread of vegetation in the area. Grasses are herbs characterized by the presence of spikelets of various sizes, which pollinate mainly in spring.
The months most at risk for reaching higher atmospheric concentrations of pollen are the warmest ones: between March and September, with a maximum peak in April and May.

Pollen calendar
Gramineae Pollination period
Oats from May to August
Wheat, chaff from May to June
Corn, sorghum from July to September
Rye from June to July
Cannarecchia from August to September
Cotton grass from June to August
Dog grass from June to October
Capellini, agroside from June to August
from May to September
Longtail grass from May to July
Paleo of meadows from April to June
Paleo, sea bass from April to June
Paleo odorous from March to July
Logliarello from May to August
Street grass from February to November
Meadow grass and barley from April to August

Risk factors

Allergy to grasses: predisposing and/or aggravating factors

Allergy to grasses is caused by pollen from one of the most widespread plant families in the world: there are around 9,000 different species, including many wild plants and herbaceous weeds, annual or perennial, which also grow spontaneously in gardens, meadows, uncultivated land and roadsides.
Furthermore, the risk of introducing the same allergens in the diet should not be underestimated: in fact, cereal- based foods belonging to the grass family are often also present at the table.

Allergen Main allergenic families Some examples
Grass pollen Spontaneous grasses Common grass, codolina, paleo odoroso, ryegrass, meadow grass
Cultivated grasses (cereals) Oats, wheat , corn , barley, rye
Allergy to grasses and foods for which a possible cross-reactivity is described
Melon , watermelon , orange and citrus fruit , kiwi , tomato , aubergine , peach , apricot , cherry, plum , peanut , almond , wheat , cereals and their derivatives ( bread and pasta ).


When the concentration of grass pollen dispersed in the environment reaches a certain threshold , the typical manifestations of allergy can occur in predisposed subjects.

Grass allergy: presentation

Symptoms vary from person to person and can be mild or severe. The manifestations associated with grass allergy can disappear as quickly and abruptly as they appeared, but sometimes persist for as long as you are exposed to the allergens. In some cases, the disorders can already manifest themselves inside closed environments (home or workplace), and then worsen outside; if the allergic person returns indoors , the situation improves, but it takes time for the symptoms to disappear.

Allergy to grasses: how does it manifest itself?

Grasses mainly cause respiratory problems :

  • Itchy nose;
  • Repeated bouts of sneezing ;
  • Abundant, light-colored nasal discharge;
  • Congestion of the nasal mucosa;
  • Difficulty breathing (dyspnea);
  • Reduction of smell .

A grass allergy attack can cause other signs and symptoms , such as:

  • Ocular irritation with annoying itching and profuse tearing ;
  • Itching of the conjunctivae, which appear red and edematous;
  • Discomfort in light (photophobia);
  • Itching in the throat , ears and/or palate ;
  • General feeling of malaise.

Long-lasting or repeated exposure to grass pollen leads, after three or four days, to obstruction of the nasal passages and ears.
In some people, exposure to grasses can trigger typical asthma symptoms , such as:

  • Shortness of breath ( air hunger );
  • Sense of chest tightness;
  • Wheezing while breathing ;
  • Dry , irritating and persistent cough.

Sometimes, tiredness , irritability, difficulty concentrating , headache , diarrhea , skin manifestations ( hives or dermatitis ), worsening of sleep quality , weakness, states of anxiety and depression also appear .

Allergy to grasses and food cross-reactions

In allergic subjects, in addition to ocular, rhinitis and/or asthmatic symptoms, implications may sometimes arise due to pollen-food cross-reactivity, which manifests itself with:

  • Itching and swelling of the oro- labial mucosa ;
  • Burning in the palate and throat;
  • Swallowing disorders .

These manifestations occur within a few minutes of ingesting plant foods, in particular with some types of fresh fruit and vegetables , containing antigens that cause cross-reactions with antigenic pollen: this is the so-called oral allergy syndrome (OSA).
In the case of an allergy to grasses, there is also the risk of anaphylactic shock , a rare complication that can cause cardiovascular collapse and must be treated promptly.


Grass allergy: how is it diagnosed?

In the presence of signs and symptoms that suggest an allergy to grasses, it is essential to consult an allergist specialist to confirm the diagnostic hypothesis and exclude other medical problems.
To define the condition, therefore, the following are indicated:

  • Anamnesis and physical examination : the doctor can reconstruct the patient’s medical history , as well as collect information relating to the symptoms and evaluate the signs present. When collecting this data, it is necessary to investigate when the disorders began, their nature, periodicity and any triggering factors already identified. The elements that can influence the occurrence of a reaction to grasses are familiarity (i.e. the existence of allergic relatives), the living conditions and the work activity of the subject in question.
  • Prick test (skin test): consists of reproducing the allergic reaction on the patient’s skin to a reduced extent. A drop of the suspected allergen is applied to the forearm or back and is made to penetrate the dermis thanks to a small prick in the area. If the person is allergic to the tested substances, a skin reaction occurs (in particular, a red and itchy swelling similar to a mosquito bite) occurs within a short time;
  • Rast test (specific IgE measurement): highlights the reaction of antibodies directed towards particular antigens on a blood sample and provides an indication of the patient’s degree of sensitivity to exposure to the allergen.


Grass allergy: what treatment is available?

The best treatment is to take appropriate measures to avoid exposure to the allergen responsible for the allergic reaction.
To manage symptoms, the following are mainly prescribed:

  • Antihistamines : histamine receptor antagonists that block the release of histamine (produced by the immune system and active during the allergic reaction), relieving most symptoms, especially itching, sneezing, nasal congestion or watery eyes.
  • Corticosteroids : nebulized through spray dispensers or taken orally in the form of tablets, can reduce the symptoms associated with inflammation of the upper respiratory tract.
  • Spray decongestants : These can be used for short periods, to provide quick relief from nasal congestion.
  • Antileukotrienes : oral drugs that help quickly block the action of certain immune system chemicals that cause certain symptoms, such as the formation of excess mucus and nasal congestion.
  • Desensitizing therapy or specific immunotherapy with allergenic extracts: the results of diagnostic tests can favor the development of a long-term desensitization treatment (3-5 years) which allows the immune response to be gradually “trained” against the allergen, reducing the number and intensity of acute episodes.


Grass allergy: preventive measures and useful advice

To control the symptoms of grass allergy, it is important to adopt some preventive behaviors:

  • Consult the pollen calendar to find out the periods of the year at risk, during which it will be appropriate to implement precautionary measures, such as the use of masks .
  • During the pollination period of grasses, avoid going out especially in the morning hours, on sunny, windy days and in dry weather. Pollen grains are mostly present in the atmosphere with a temperature of 25-30° C, a relative humidity above 60% and a wind speed of 5-15 km/h. For susceptible individuals, it is also risky to go out after a storm: the rain breaks the pollen grains into smaller fragments that easily reach the airways.
  • To prevent pollen from entering the house during the flowering season, keep the windows closed during sunny hours, approximately between 10am and 4pm. Do not hang the sheets outdoors to avoid them collecting pollen.
  • Avoid parking your car under trees or near gardens and/or lawns. When travelling, however, preferably keep the windows closed and equip the car with anti-pollen filters, taking care to replace them periodically.
  • Shower and wash your hair and face more frequently, as pollen grains can remain on the skin or in your hair and settle on the pillow from where they are inhaled during sleep or can cause dermatitis.
  • Take care of the cleanliness of pets: if they go outdoors they can become vectors of grass pollen through their fur .
  • Avoid frequenting parks, gardens and lawns, especially if they have recently been mowed.
  • Be careful with alcohol : it stimulates the production of mucus and dilates the vessels, risking worsening the secretion and nasal congestion associated with grass allergy.

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