Allergic rhinitis is a picture of inflammation of the mucous membranes of the nasal cavity caused by an exaggerated reaction of the immune system to allergens in the air. In this text, we will explain the mechanisms that trigger allergic rhinitis, its symptoms and treatment options.
What Is Allergy?
Allergen is any particle that can trigger an allergic reaction, which is nothing more than a reaction of your immune system to foreign agents. Allergens can come into contact with our body by:
- Inhalation, such as pollen, smoke, chemicals, dust, etc.
- Ingestion, such as meals, medications, and supplements.
- Contact with the skin, such as perfumes, chemicals, creams, latex, plants, etc.
- Inoculation on the skin, such as insect bites.
What causes the allergic reaction is not a direct and active action of the allergen, but the body’s exaggerated response to contact with it. This explains why some people have allergies to individual particles and others do not. Pollen, for example, can be an allergen for some and harmless for others.
Rhinitis is actually inflammation of the mucous membranes of the nasal cavity, usually caused by a viral infection or an allergic reaction. In this text, we are going to stick to allergic rhinitis.
In the next two paragraphs I will use some technical terms to explain the mechanism of inflammation of allergic rhinitis, but do not worry, I will try to use analogies and be as transparent as possible. The information to follow will be essential to understand how some of the treatments work.
How Does Allergic Rhinitis Emerge?
Allergic rhinitis arises when an allergic person inhales some particle that stimulates their immune system. In childhood, we come into contact with different potential allergens without having significant problems.
Allergic people are those who, when they come into contact with individual particles, produce antibodies against them, as if they were harmful invading agents, such as viruses, bacteria, etc.
We are going to use pollen as an example. People who are allergic to dust are those who, when they come into contact with this allergen for the first time, produce in large quantities an antibody called IgE.
From this moment, the nasal mucosa begins to be populated with an immune system cell called a mast cell, which has several IgE antibodies on its surface.
It is as if the body thought that the pollen is an assailant and therefore went to fill the nasal cavity of highly armed guards (mast cells) (IgE). So when the person comes back in contact with the pollen, the IgE antibodies quickly capture it, activating the mast cells that release several chemical mediators to destroy the invader, being the most important the histamine, responsible for the main symptoms of rhinitis, the which will be explained later.
The allergic symptoms of allergic rhinitis are, therefore, a side effect of the chemical warfare that the immune system maintains against some particles. Pollen itself does not cause any harm, but the allergic immune system does not think so.
Non-allergic people are those who come into contact with pollen, for example, and do not correctly develop specific IgE against it. In other words, the body recognizes pollen as a foreign particle, but does not see it as a threat and does not produce antibodies against it.
Risk Factors Of Allergic Rhinitis
As allergic rhinitis is nothing more than an allergic reaction of the nasal cavity, people with other diseases of allergic origin, such as asthma, eczema, allergic conjunctivitis, urticaria, etc., have a higher risk of having allergic rhinitis.
Other risk factors for allergic rhinitis include:
- Being male.
- Family history of allergies.
- Birth during the pollen season.
- Babies who stopped breastfeeding early.
- Frequent disclosure to cigarette smoke in the first year.
- Early exposure to antibiotics.
- Work or live in environments rich in potential allergens.
Symptoms Of Allergic Rhinitis
Symptoms of allergic rhinitis include runny nose, sneezing, nasal congestion, watery eyes and itchy eyes, nose, and palate (roof of the mouth). Sinusitis is also frequent, with a picture of rhinosinusitis (rhinitis + sinusitis). Other common symptoms are: a sore throat, snoring, cough and decreased palate and smell.
Two typical signs of allergic rhinitis are the deepening of the lines of the lower eyelids (signal called Dennie-Morgan lines) and the darkening of the skin under the eyes, like an eye-cup. The picture shown below illustrates these two signs well.
Allergic rhinitis in some people can be seasonal, occurring only at certain times of the year. In contrast, many patients present an almost endless picture of allergic rhinitis, such as numerous episodes throughout the year. These, in general, are those who are exposed to allergens regularly, whether at home or work.
If the patient lives in a medium where he is exposed to the allergen frequently, the tendency is for the symptoms to worsen and consequently a lower amount of allergen to be able to trigger the seizures.
Some people become so sensitive that other factors can happen to trigger rhinitis, such as exposure to cold, smoke or strong smell.
Treatment Of Allergic Rhinitis
In addition to the control of symptoms, the treatment of allergic rhinitis should always be aimed at reducing exposure to allergens that trigger seizures. If the allergen is unknown, there are skin allergy tests that can identify it.
1- Saline solution
Washing the nostrils (external nostrils) with saline or other salt solutions is efficient to eliminate allergens attached to the nasal mucosa in those milder cases. Washing can be done few times a day and can be used to clean the cavity before the applications of other medicines.
2- Nasal decongestants
For many years, nasal decongestants were the most popular medications in the treatment of rhinitis. The most commonly used substances are pseudoephedrine, phenylephrine, and oxymetazoline. These medicines can cause a constriction of the nasal vessels, decreasing the secretion of mucus and relieving symptoms.
However, we should not use nasal sprays for more than three days in a row, as they usually cause dependence, which causes the nose to become stupid again unless such decongestants are used still. This addiction is severe to reverse.
Since histamine is the substance that causes the symptoms of allergic rhinitis, antihistamine medications can be used for treatment. However, although antihistamines reduce sneezing, itching and nasal discharge, they are not as effective against nasal congestion that the use of a decongestant becomes necessary.
The association of a nasal solution combining an antihistamine and a decongestant is pervasive in the market.
Antihistamines can also be taken in tablets. However, they usually cause some drowsiness. The most common is Loratadine, desloratadine, cetirizine, levocetirizine, diphenhydramine, clemastine and fexofenadine.
4- Nasal Corticoids
Nasal corticosteroids are currently the first line medication in the treatment of allergic rhinitis. There are several options in the market: fluticasone, mometasone, budesonide, flunisolide, triamcinolone, and beclomethasone.
All these have practically the same effectiveness. Patients with very severe nasal congestion sometimes need to use nasal decongestants and antihistamines for one or two days before starting the corticosteroid, so that it is more efficient.
Nasal corticosteroids are useful in the treatment and prevention of allergic rhinitis and can be used even outside crises.
Contrary to systemic corticosteroids, nasal corticosteroids are safe medications that can be used for many years afterward. It is hardly advised that patients who are using nasal corticosteroids for prolonged periods have their nasal cavity examined periodically by an otolaryngologist to avoid the rare complications, such as mucosal lesions and infections.
Also called “vaccines,” immunotherapy is a treatment aimed at desensitizing the patient regarding allergens. They consist in the injection of small doses of the allergen so that the organism gets used to it, thus decreasing the response to its exposure.
Immunotherapy currently only exists for the most common allergens, such as pollen, mites, animal hairs, etc. The treatment lasts some years and should not be interrupted because it runs the risk of losing its effectiveness.