After a tough winter of Covid-19, we will shortly have the joys of spring to look forward to. But the warmer days and buds on the trees are accompanied by a season of higher pollen counts, which can make this time of year considerably less enjoyable for a hay fever sufferer. Come March, patients who suffer from severe hay fever symptoms are often desperate to get their hands on their usual hay fever medications. The current climate of Covid-19 pandemic raises a number of questions about these medications and this common condition.
How can we distinguish between hay fever and Covid-19?
The hay fever season of 2020 was less complicated when we believed that runny nose was not a feature of Covid-19. Recently, however, GPs have called for the Government to include runny nose and cold, with the technical term coryza, to the list of symptoms that require people to get a Covid-19 test.1 New disease variants, perhaps combined with better testing, seem to have caused an increase in the number of patients with mild symptoms, such as a blocked nose and headache, who turn out to be Covid-19 positive. This could potentially cause havoc for hay fever sufferers who need to be able to distinguish between their seasonal condition and Covid-19. We need to remember the following key points. Hay fever does not cause a fever. Hay fever is not usually associated with excessive fatigue, muscle aches, or feeling unwell. Hay fever symptoms include itchy, watery eyes and are generally worse when the pollen count is higher. It may be helpful for patients to keep track of the daily or weekly pollen count and compare with their symptoms. If a patient’s symptoms feel like their usual hay fever symptoms and fit with the pollen count or time of year when they usually suffer, then the chances are that they have hay fever and not Covid-19. Although we cannot say for sure.
Is it safe to take my usual hay fever medications?
Yes. Common treatments for hay fever include oral antihistamines and intra-nasal corticosteroids (INCS). There is no evidence that these may be harmful to take in Covid-19. In fact, there are a number of ongoing studies looking into whether antihistamines could play a role in both preventing someone from catching Covid-19 and in treating patients with severe Covid-19 infection.2 Among the agents being tested are hydroxyzine (sold as Atarax), diphenhydramine (Benadryl), azelastine (available as a nasal spray) and famotidine (an H2 receptor antagonist usually used to treat gastric symptoms). Antihistamines block airway inflammation and bronchoconstriction provoked by histamine release from mast cells. 3 Mast cell stabilisers such as sodium cromoglicate are commonly used to treat hay fever in the form of eye drops. Mast cells play a central role in the ‘cytokine storm’ that has affected many hospitalised patients with Covid-19.4
There is also no current evidence that INCS should be avoided or that their use could increase infectivity or worsen symptoms of Covid-19 infection.5
What are the advantages of treating hay fever?
Hay fever symptoms can be severely debilitating for many. As well as making life more bearable for sufferers, alleviating patients’ symptoms has significant benefit for others. Sneezing causes clouds of droplets to be propelled much farther than droplets that are simply exhaled. One study published in JAMA6 demonstrated that the force of a sneeze can cause potentially pathogen-bearing droplets to travel 7-8m, both contaminating surfaces along that trajectory and remaining suspended in the air for hours. Two metre social distancing and simple surgical or cloth masks will be insufficient protection for others if the person who sneezes has Covid-19. Some patients with Covid-19 will also have hay fever and vice versa. If sneezing increases the risk of transmission of Covid-19, then treatments which reduce coryza and sneezing have a direct benefit in helping to lessen the spread of Covid-19 infection. Similarly, blowing the nose also generates aerosols and is associated with potential contamination of surfaces by subsequent touch. There is an argument, therefore, for actively advising people with hay fever that it is both safe to use their treatments and sensible to use them regularly.
So should we all take an antihistamine?
No. There is currently insufficient evidence to demonstrate whether antihistamines help in the prevention or treatment of Covid-19. No medication is entirely without risk of side effects or interactions and we should not recommend taking a drug for which there is no evidence base. Furthermore, some of the studies currently being done on antihistamines and Covid-19 are using doses that are higher than usual prescribed oral dosage or giving the medication intravenously. It will be interesting to see what data emerges from these studies, however.
3. Histamine release theory and roles of antihistamine in the treatment of cytokines storm of Covid-19, Omar Abdelhay Eldanasory, Khalid Elijaaly, […], and Jaffar A. Al-Tawfiq, Travel Medicine and Infectious Disease. 2020 Sept-Oct; 37:101874
4. Mast cell stabilisers, leukotriene antagonists and antihistamines: A rapid review of the evidence for their use in Covid-19, Meriel Raymond, Gemma Ching-A-Sue, Oliver Van Hecke, The Centre for Evidence-Based Medicine. Evidence Service to support the COVID-19 response, University of Oxford. May 18, 2020
5. Perspective: Covid-19, implications of nasal diseases and consequences for their management, Li Jian, Wei Yi, Nan Zhang, Olga Krysko, Woo-Jung Song, Claus Bachert, The Journal of Allergy and Clinical Immunology. Vol 146, issue 1, p67-69, July 01 2020
6. Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of Covid-19, Lydia Bourouiba, PhD, JAMA. 2020;323(18):1837-1838