According to the Allergy Foundation of South Africa (AFSA); the bulk of allergens that have higher levels during winter are indoor allergens; including house dust mites; moulds; cockroaches and pet dander. The reason for increased exposure to such allergens during winter months is a reduction in indoor ventilation and an associated increase in indoor humidity levels, and a greater amount of time spent indoors in contact with such allergens. 

Hyrkäs-Palmu et al found that AR patients experience cold weather-related functional disability more commonly (25.1% and 19.2%) compared to their counterparts without the disease. In addition; AR increases the experience of cold weather-related exacerbation of health problems, with men being more affected than women. 

According to the authors; functional disability and exacerbation of health problems during cold weather are due to the cooling and drying of respiratory epithelium; which may induce chronic inflammation; increasing symptoms.  

Winter-related allergy mediators

AFSA states that winter-related allergies can be mediated in three ways: 

• Exposure to those allergens which are more prolific during the winter months leading to typical AR or asthma
• Worsening of allergies and asthma secondary to winter viruses
• Worsening of symptoms because of the cold air itself.
  

Treatment

Treatments for AR comprise allergen avoidance; pharmacotherapy and immunotherapy. For SAR; total allergen avoidance may be undesirable; as it may require limiting time spent outdoors. Thus; pharmacotherapy is preferable to allergen avoidance for symptom relief of SAR. 

Six classes of agents and nasal saline are recommended for the treatment of SAR: 

• Antihistamines (AH) 
• Corticosteroids (CS)
• Decongestants
• Ipratropium
• Intranasal mast cell stabilisers
• Cysteinyl leukotrienes

The 2020 Joint Task Force on Practice Parameter guideline recommends the following treatment for SAR:  

• Intranasal AH (INAH) are equal to or superior to oral AH for the relief of nasal symptoms and may benefit patients who fail on the latter treatment INAH has a more rapid onset of action compared to intranasal corticosteroids (INCS)  
• Combination of an INCS and an INAH for the initial treatment of moderate to severe nasal symptoms of SAR in patients age ≥12 
• Combination of an INCS and an INAH for treatment-resistant moderate to severe disease 
• Patients with persistent nasal congestion unresponsive to an INCS or to an INCS/INAH combination be offered combination therapy with the addition of an intranasal decongestant for up to four weeks. 

How effective is combination therapy? 

Gross et al (2019) evaluated the efficacy and safety of a fixed-dose combination of olopatadine hydrochloride (INAH) and mometasone furoate (INCS) in patients (older than 12 years) with SAR.  

The combination of olopatadine hydrochloride/mometasone furoate provided statistically significant and clinically meaningful Total Nasal Symptom Score (rTNSS) improvements vs placebo, and vs olopatadine and mometasone monotherapy.  

The onset of action with the combination therapy is within 15 minutes and maintained at all subsequent time points. Treatment-emergent AEs occurred in 15.6%, 12.6%, 9.6% and 9.5% of patients in the combination, olopatadine, mometasone and placebo groups, respectively. 

The efficacy of combination olopatadine hydrochloride/mometasone furoate was evaluated in paediatric patients (n=431) aged 6 to 12. This was a phase 3 study comparing the effectiveness of combination therapy (administered as one spray in each nostril, twice daily) versus a placebo nasal spray over 14 days in paediatric patients with SAR.  

The rTNSS was assessed by 12-hour reflective scoring of the severity of four nasal symptoms (rhinorrhoea, sneezing, nasal congestion and nasal itching). Patients treated with combination therapy compared to placebo showed a statistically significant improvement for the primary endpoint of average morning and evening rTNSS.  

Rates of AEs were similar between the combination therapy versus the placebo group (10.4% vs 12.0%, respectively). The most common AEs included distortion of taste sensation (combination 1.3% vs placebo 0.0%), headache (combination 1.3% vs placebo 0.5%) and nose-bleed (combination 0.9% vs placebo 2.3%). 

*References available on request