Last updated date: 13-Apr-2023
Originally Written in English
Allergic rhinitis (AR) is a heterogeneous condition that, despite its great frequency, frequently remains misdiagnosed. It has one or more symptoms such as sneezing, itching, nasal congestion, and rhinorrhea. Pollens, molds, dust mites, and animal dander are just a few of the factors that have been implicated to allergic rhinitis.
Seasonal allergic rhinitis is very straightforward to recognize due to the quick and consistent start and resolution of symptoms in response to pollen exposure. Because of the overlap with sinusitis, respiratory infections, and vasomotor rhinitis, perennial allergic rhinitis is sometimes more difficult to identify than seasonal allergic rhinitis. Once pollen season is ended, seasonal allergic rhinitis can cause hypersensitivity to allergens such as cigarette smoke. Perennial allergic rhinitis is characterized as occurring for at least 9 months of the year.
Allergic rhinitis affects an estimated 20 to 40 million individuals in the United States alone, and the prevalence is rising; an estimated 20% of cases are seasonal allergic rhinitis, 40% are perennial rhinitis, and 40% are mixed.
Seasonal allergic rhinitis has a complicated pathogenesis. The allergic reaction has a substantial genetic component, which is driven by mucosal infiltration and action on plasma cells, mast cells, and eosinophils.
The allergic reaction is divided into two stages, known as the "early" and "late" phases. The early phase reaction begins within minutes of allergen contact and is characterized by sneezing, itching, and obvious rhinorrhea. The late phase response follows 4 to 8 hours later and is marked by congestion, weariness, malaise, irritability, and perhaps neurocognitive impairment.
Today, IgE antibody tests to detect particular allergens are the conventional technique of diagnosis; however, a positive history and confirmation that the symptoms are the consequence of IgE-mediated inflammation are also required.
Epidemiology of allergic rhinitis
Based on physician diagnosis, the prevalence of allergic rhinitis is around 15%; however, the prevalence is believed to be as high as 30% in patients with nasal symptoms. AR is known to peak during the second and fourth decades of life before progressively declining. AR is also highly frequent in the pediatric population, making it one of the most common chronic pediatric illnesses.
According to data from the International Study of Asthma and Allergies in Childhood, 14.6 % of 13 to 14-year-olds and 8.5 % of 6 to 7-year-olds had rhinoconjunctivitis associated with allergic rhinitis. Seasonal allergic rhinitis appears to be more frequent in children, but chronic rhinitis is more common in adults.
According to a 2018 systematic study, 3.6 % of individuals missed work and 36 percent reported reduced job performance owing to allergic rhinitis. Economic analyses have revealed that the bulk of the cost-burden for AR is accounted for by indirect expenses linked with reduced job productivity.
Pathophysiology of allergic rhinitis
Imbalances in innate and adaptive immunity, as well as environmental variables, are likely to play important roles. Initial allergen exposure and sensitization in allergic rhinitis includes antigen-presenting cells, T and B lymphocytes, and leads in the production of allergen-specific T cells and allergen-specific IgE antibodies.
Cross-linking of IgE on mast cells upon re-exposure to relevant allergens results in the release of hypersensitivity mediators such as histamine. Within hours, inflammatory cells, mainly T lymphocytes, eosinophils, and basophils, infiltrate nasal mucosal tissue, resulting in the late-phase allergic reaction.
Allergic rhinitis causes
Traditionally, allergic rhinitis has been classified as either seasonal (occurs just during a particular season) or perennial (occurs throughout the year). However, this categorization approach does not apply to all cases. Some allergy triggers, such as pollen, may be seasonal in cooler areas but perennial in warmer climes, and individuals with numerous "seasonal" allergies may experience symptoms all year. As a result, allergic rhinitis is now categorised based on the duration of symptoms (intermittent or persistent) and severity (mild, moderate, or severe).
Intermittent allergic rhinitis is defined as symptoms that occur less than four days per week or for less than four consecutive weeks, and persistent allergic rhinitis is defined as symptoms that occur more than four days per week or for more than four consecutive weeks.
When individuals have no sleep disturbances and are able to complete routine activities, their symptoms are classed as mild. Symptoms are classified as moderate/severe if they considerably interfere with sleep or everyday activities and/or are deemed annoying. It is critical to categorize the intensity and duration of symptoms since this will guide the therapeutic strategy for specific patients.
In recent years, two new kinds of rhinitis have been identified: occupational rhinitis and local allergic rhinitis:
Occupational rhinitis is described as an inflammatory condition of the nose characterized by intermittent or chronic symptoms such as airflow constriction, hypersecretion, sneezing, and pruritus that are caused by a specific work environment and not by external stimuli.
Despite the fact that the total occurrence of occupational rhinitis is undetermined, high-risk occupations include laboratory or food-processing employees, veterinarians, farmers, and workers in different industrial industries. Occupational rhinitis often manifests itself within the first two years of employment. The condition might be IgE-mediated as a result of allergen sensitivity or exposure to respiratory irritants.
Symptoms may appear immediately or after many hours of being exposed to the triggering stimuli. There are frequently related ocular and respiratory symptoms. The regular history and physical examination, as well as a site visit and skin testing or in vitro testing to inhalants, should be performed on a patient suspected of having occupational rhinitis.
Treatment consists mostly on avoiding exposure to the causal cause and, if necessary, medicines. Although it is conceivable, there is limited evidence that occupational rhinitis may advance to occupational asthma with continued exposure. As a result, if exposure cannot be removed but symptoms are sufficiently managed, patients are often not recommended to leave their occupations.
Local allergic rhinitis:
Local allergic rhinitis is a clinical condition distinguished by a localized allergic reaction in the nasal mucosa in the absence of systemic atopy. Individuals with local allergic rhinitis have negative IgE skin tests, but evidence of local IgE synthesis in the nasal mucosa; these patients also react to nasal challenges with particular allergens.
The symptoms of local allergic rhinitis are similar to those of allergic rhinitis, and it is assumed that local allergic rhinitis is an IgE-mediated illness based on clinical observations as well as the identification of specific IgE in the nasal mucosa.
There is no evidence to date that local allergic rhinitis is a precursor to allergic rhinitis since patient follow-up does not indicate the development to typical allergic rhinitis in these individuals; however, patient follow-up may not have been long enough to identify this disease evolution.
The implications for local allergic rhinitis treatment are yet unknown, while some data shows that allergen immunotherapy may be useful in this kind of rhinitis.
Risk factors for allergic rhinitis
Atopy in the family, male sex, allergen-specific IgE, serum IgE more than 100 IU/mL before the age of 6, and higher socioeconomic position are all risk factors. Early introduction of meals or formula, as well as excessive exposure to cigarette smoking in the first year of life, have been linked to an increased incidence of allergic rhinitis in young infants.
Despite the fact that numerous recent research have looked at the relationship between pollution and the development of allergic rhinitis, no substantial correlation has been found. Surprisingly, some variables have been found that may protect against the development of allergic rhinitis.
The role of breastfeeding in the development of allergic rhinitis is frequently contested, although it is still encouraged owing to its numerous other recognized advantages and lack of related hazards. There is no evidence that pet avoidance in childhood prevents allergic rhinitis.
Allergic rhinitis symptoms and signs
Rhinorrhea (excess nasal discharge), itching, sneezing, and nasal congestion are all symptoms of allergic rhinitis. Conjunctival edema and erythema, eyelid swelling with Dennie–Morgan folds, lower eyelid venous stasis (rings beneath the eyes known as allergic shiners, swollen nasal turbinates, and middle ear effusion are also common physical findings.
There may also be behavioural characters for example, to alleviate discomfort or mucus flow, people may wipe or massage their nose with the palm of their hand in an upward motion, a technique known as the nasal salute or the allergic salute. This can cause a crease to run across the nose which is known as the transverse nasal crease, and can lead to lifelong physical deformities if done repeatedly.
People who are sensitive to birch pollen may also be allergic to the skin of apples or potatoes. An itchy throat after eating an apple or sneezing while peeling potatoes or apples are evident signs of this. This happens because the proteins in pollen and food are identical. There are several compounds that react with one another. Hay fever is not a real fever, which means that it does not raise the core body temperature over 37.5–38.3 °C.
Diagnosis of allergic rhinitis
Allergic rhinitis is largely a clinical diagnosis made based on a thorough history, physical examination with aid of serum testing for allergen-specific IgE or allergy skin testing:
Detailed medical history:
It is primarly required for AR assessment, and questioning should focus on the types of symptoms, the timing, duration, and frequency of symptoms, possible exposures, exacerbating/alleviating variables, and seasonality. Those with intermittent or seasonal allergic rhinitis have sneezing, rhinorrhea, and watery eyes, but patients with chronic AR frequently experience postnasal drip, persistent nasal congestion, and blockage. These individuals frequently have a familial history of allergic rhinitis or an individual history of asthma.
Mouth breathing, frequent sniffling and/or throat clearing, a transverse supra-tip nasal wrinkle, and dark circles under the eyes may be observed by doctors . Anterior rhinoscopy often indicates nasal mucosal edema and thin, clear secretions. The inferior turbinates may become blue, and nasal mucosa cobblestones may be seen.
Pneumatic otoscopy can be performed to check for eustachian tube dysfunction, which is frequent in allergic rhinitis patients. In patients with persistent complaints, palpation of the sinuses may cause soreness. These individuals should also be thoroughly examined for indications of asthma or dermatitis, and their aspirin sensitivity should be tested.
Serum testing for allergen-specific IgE or allergy skin testing:
Allergy testing should be reserved for individuals who do not respond to empiric treatment or who need to identify a specific allergen to target therapy. Serum testing does not necessitate the use of experienced technicians, and the patient is not required to discontinue antihistamines ahead of time.
Intradermal allergy testing does need the use of a skilled specialist; however, the findings are available instantly. Testing should be undertaken on individuals with seasonal symptoms during the peak symptom season in order to identify particular triggers.
Skin testing is reported to have somewhat higher sensitivity than serum testing and to be less expensive. Patients with uncontrolled or severe asthma, unstable cardiovascular illness, pregnancy, and/or concomitant beta-blocker medication are all contraindications to skin allergy testing.
Treatment of allergic rhinitis
The purpose of rhinitis therapy is to avoid or alleviate the symptoms induced by inflammation in the afflicted tissues. Avoiding the allergen is one of the most effective measures. For prolonged symptoms, intranasal corticosteroids are the primary medical treatment, although there are alternative choices if these drugs don't work. Antihistamines, decongestants, cromolyn, leukotriene receptor antagonists, and nasal irrigation are examples of second-line treatments.
Antihistamines taken by mouth are appropriate for moderate intermittent symptoms. There is no evidence that mite-proof covers, air filters, or withholding particular meals from children are useful.
Sneezing, rhinorrhea, itching, and conjunctivitis can all be treated with antihistamine drugs, which can be given orally or nasally.It is best to take oral antihistamine medication before exposure, especially for seasonal allergic rhinitis. Relief from symptoms is achieved within 15 minutes with nasal antihistamines like azelastine antihistamine nasal spray.
Antihistamine effectiveness as an add-on therapy with nasal steroids in the management of intermittent or chronic allergic rhinitis in children is not well established, thus side effects and additional expenses must be taken into account. Conjunctivitis is treated with ophthalmic antihistamines, whereas sneezing, rhinorrhea, and nasal pruritus are treated with intranasal antihistamines.
Antihistamines have a series of adverse side effects, the most significant of which being drowsiness in the case of antihistamine pills. Drowsiness is more probable with first-generation antihistamines like diphenhydramine, whereas second- and third-generation antihistamines like cetirizine and loratadine are less likely to.
Vasomotor rhinitis is also treated with pseudoephedrine. It's only used when there's nasal congestion, and it's safe to use alongside antihistamines. To prevent the manufacture of methamphetamine, oral decongestants containing pseudoephedrine must be purchased behind the pharmacy counter in the United States. This condition can also be treated with desloratadine/pseudoephedrine.
Sneezing, rhinorrhea, itching, and nasal congestion can all be controlled by intranasal corticosteroids. Nasal steroid sprays are efficient and safe, and they may be used instead of antihistamines. They take many days to take effect and must be taken on a regular basis for several weeks to achieve their therapeutic effect.
Prednisone pills and intramuscular triamcinolone acetonide or glucocorticoid (such as betamethasone) injections are efficient at reducing nasal inflammation, but their usage is limited due to the short duration of action and the negative effects of extended steroid therapy.
Allergen immunotherapy includes providing allergen dosages to acclimatize the body to generally harmless substances (pollen, home dust mites), resulting in particular long-term tolerance. The only treatment that affects the disease mechanism is allergen immunotherapy. Immunotherapy can be given orally (as sublingual pills or drops) or subcutaneously. The most prevalent type of immunotherapy is subcutaneous immunotherapy, which has the most evidence supporting its effectiveness.
Decongestants, cromolyn, leukotriene receptor antagonists, and non-pharmacologic therapy such as nasal irrigation are examples of second-line treatments.
Topical decongestants can also assist with symptoms like nasal congestion, but they shouldn't be taken for long periods of time since quitting them after a long period of usage might cause rhinitis medicamentosa, or rebound nasal congestion.
Intranasal corticosteroids can be used in combination with nightly oxymetazoline, an adrenergic alpha-agonist, or an antihistamine nasal spray to treat nocturnal symptoms without causing rhinitis medicamentosa.
Nasal saline irrigation may help relieve the symptoms of allergic rhinitis in both adults and children, and it is unlikely to have any side effects.
Prognosis of allergic rhinitis
According to public view, the prevalence of allergic rhinitis peaks in adolescence and subsequently declines with age. In a 23-year follow-up of a longitudinal trial, 54.9 % of patients demonstrated improvement in symptoms, with 41.6 % of those being symptom-free. Patients with symptoms that began at a younger age were more likely to improve. Allergic rhinitis severity varies with time and is influenced by a variety of factors such as location and season. Approximately half of patients who received grass allergy immunotherapy reported relief in symptoms that lasted three years after the treatment was stopped.
Allergic rhinitis complications
Although chronic rhinosinusitis is not the same as allergic rhinitis, it can be a side effect of AR. It's characterized by nasal inflammation and nasal congestion or discharge that lasts longer than three months.
Nasal polyps (nasal polyposis) can develop as a result of prolonged inflammation of the paranasal sinus mucosa in chronic rhinosinusitis. Nasal polyps are usually harmless and appear on both sides of the nose. Unilateral nasal polyps should be treated with caution since they might be cancerous. Nasal polyps affect around 4% of the population and are more frequent in men. Topical steroids and saline irrigation are two alternatives for treatment. Patients who do not respond to medical treatment are considered candidates for surgical removal.
Sensitization to allergens in AR has also been shown to affect the immunological characteristics of the adenoids, leading to adenoid hypertrophy. Ear fullness, otalgia, and ear-popping are prominent symptoms of eustachian tube dysfunction in AR patients.
Around 10% to 40% of individuals with AR also have asthma, and some research imply that asthma is more likely in patients with moderate to severe persistent rhinitis. AR has been shown in several studies to be an independent risk factor for asthma, particularly in people identified with AR as a child. Some other associated complications include otitis media with effusion, recurrent cough, and eosinophilic esophagitis, although there is a need to define the link more clearly.
Patients who get allergen desensitization may develop an abrupt aggravation of rhinitis or asthma, or, in the worst-case scenario, develop anaphylaxis. As a result, personnel at offices that give this therapy should be well-versed in the detection and care of such severe responses, as well as having the necessary emergency drugs (particularly epinephrine) and airway management equipment.
Rhinitis is a condition in which the mucous membrane of the nose becomes irritated and swells. There are two types of rhinitis: allergic and nonallergic. Allergic rhinitis is caused by a type 1 hypersensitivity reaction, which results in nasal mucous membrane irritation.
Allergic rhinitis is a frequent condition associated with asthma and conjunctivitis. It is usually a long-standing condition that often goes undetected in the primary-care setting. Nasal congestion, nasal irritation, rhinorrhea, and sneezing are common symptoms of the disease.
The diagnosis of allergic rhinitis requires a complete medical history, physical examination, and allergen skin testing. The majority of therapy is second-generation oral antihistamines and intranasal corticosteroids. If pharmacological therapy for allergic rhinitis is ineffective or not tolerated, or if the patient requests it, allergen immunotherapy is an effective immune-modulating treatment.