Background
Allergic rhinitis is a common condition which can be hugely debilitating despite not contributing to national morbidity or mortality. It has been shown to adversely affect activities of daily living of nearly 1.38 million Irish people. Chronic allergic rhinitis is broadly divided into seasonal and perennial allergic rhinitis. Approximately 60% of patients with allergic rhinitis have concomitant allergic rhino conjunctivitis. The allergic march theory has shown that untreated allergic rhinitis is associated with other allergic conditions like food allergies, eczema and asthma.
Patient symptoms
Nasal symptoms characterise this condition. Patients usually notice rhinorrhea or nasal discharge (runny nose) or nasal congestion. Nasal pruritus or itching is also common. A less recognized symptom is post-nasal drip which is the sensation of constant mucus in the back of the mouth leading to frequent swallowing.
Ocular symptoms are usually bilateral itching, tearing or burning sensation in the eyes.
When severe, it is important to recognize that rhinitis symptoms can lead to sleep disturbance and impairment in daily activities at school, sports or work.
Treatment
Historically allergic rhinitis has always been treated with topical therapies like nasal corticosteroids and oral antihistamines. There are also several over-the-counter therapies which provide local relief. There is emerging use of allergen immunotherapy for severe or refractory allergic rhinitis in giving long-term symptomatic relief both to nasal symptoms and potentially concomitant asthma symptoms.
Allergen avoidance
Environment and lifestyle changes alone do little to interfere with the natural course of the disease. Still indoor allergen avoidance is useful in reducing total symptomatic burden of the disease. A careful history is paramount to effective allergen control. In Ireland, common aeroallergens implicated in worsening allergic disease are animal dander, dust mites, indoor mold and rodents.
Each aeroallergen requires different measures to help reduce unnecessary exposure. HDM exposure occurs mostly during sleep, and time spent indoors near carpeted floors and upholstery. Usage of woven fabrics or special allergen-impermeable covers for mattress, duvets, pillows and box beds are highly recommended. Bedding should be washed at least weekly in hot water. Carpets are discouraged from bedrooms. Upholstered furniture should be replaced by leather, vinyl or wood furniture. Animal dander like cat allergen is easily transferred on clothing and this passively transferred allergen can become airborne and cause symptoms in houses without the animal. Interestingly despite popular mainstream advertising, there is no significant evidence that certain breeds of dogs are hypoallergenic. Any evidence of indoor mold should be removed with a dilute bleach solution or fungicide immediately.
Pharmacologic therapies
It is important to differentiate over-the-counter therapies and prescription therapies for allergic rhinitis.
Nasal decongestant sprays are highly effective if used infrequently.
In Ireland, available options include Sudafed nasal spray (xylometazoline HCL), Otrivin (xylometazoline HCL), and Afrin (oxymetazoline HCL). Despite being readily available over-the-counter, caution should be advised as incorrect use can lead to adverse effects. It is important that patients are aware that these decongestant sprays are not recommended for monotherapy in chronic allergic rhinitis. Down-regulation of alpha-adrenergic receptor develops after 3 to 7 days causing rebound nasal congestion. This rebound nasal congestion frequently requires more decongestant applications and potentially culminates in physiological and psychological dependence on nasal decongestants.
Nasal saline irrigation is most effective when used for mild symptoms or before intranasal glucocorticoid application. Commercially available solutions like Sterimar nasal products are popular but patients can also make their own irrigation solutions using careful hygienic practices.
A physician should first consider an intranasal glucocorticoid (INGC).
Options include;
AvamysⓇ(fluticasone furoate)
NasonexⓇ (mometasone furoate)
Flixonase (fluticasone propionate)
If symptoms remain refractory to just a INGC prescribe a 2nd genaeration oral antihistamine. The newer antihistamines are largely non-sedating unlike Piriton chlorpheniramine which can be very sedating and useful only if nocturnal symptoms predominate. In Ireland, there is a wide selection of prescription 2nd gen oral antihistamines e.g.
ClaritynⓇ loratidine
ZirtekⓇ cetirizine
TelfastⓇ fexofenadine
XyzalⓇ levocetirizine
Drynol bilastine
There is emerging evidence behind using a novel combination intranasal glucorticoid and oral antihistamine for severe allergic rhinitis. This option is best suited for combined allergic rhino conjunctivitis not controlled on just INGC. This is marketed in Ireland as a nasal spray called Dymista which combines azelastine (oral antihistamine) and fluticasone propionate (INGC).
For patients with allergic rhinitis refractory to INGCs and concomitant asthma, a trial of a leukotriene receptor antagonist such a montelukast is advised. Similarly, if ocular symptoms are the predominant manifestation, a trial of an antihistamine eye drop is advised.
Immunotherapy
Immunotherapy has come back to the forefront of allergic rhinitis therapy as it the only treatment now shown to modify the disease characteristics on a long-term basis even after AIT is discontinued. Prolonged desensitization using increasing doses of the culprit allergen both by subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) reduces rhinitis symptoms which have been refractory to IGNC and oral antihistamines.
To date both grass pollen SLIT and hose dust mite SLIT have been proven to be safe and effective. Despite the recognized safety profile of SLIT, therapy should still be initiated in a hospital setting under the supervision of trained health care professionals due to theoretical concerns from historical SLIT data. In Ireland currently grass pollen SLIT is licensed under the GMS. A 5-grass-pollen tablet has demonstrated efficacy for up to 2 years after treatment in a double-blind placebo-controlled randomized phase 3 trial. Efficacy of house dust mite SLIT or allergy tablets have been demonstrated in both challenge chambers and a double-blind placebo-controlled randomized phase 3 trial in adults with moderate-to-severe HDM induced allergic rhinitis.
Emerging evidence also shows that AIT has the potential to treat concomitant asthmatic symptoms and also prevent the onset of allergic asthma.
Other emerging therapies
Biologics like omalizumab and dupilumab have demonstrated efficacy in proof of concept studies in patients with chronic allergic rhinitis and with nasal polyps. These monoclonal antibodies target type 2 inflammatory cytokines, including IL-4, IL-5, 1L-13 and IgE and have convincing evidence in proof of concept studies. Cost will remain a prohibitive factor in getting the required reimbursements as treatment for a chronic disease like allergic rhinitis.
It is important to differentiate over-the-counter therapies and prescription therapies for allergic rhinitis.