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Back What is allergic rhinitis? Allergic rhinitis (AR) is a medical condition that involves nasal symptoms: blocking, running, itching, and sneezing, caused by allergens entering the nose of someone who is sensitized*. In some people, allergens also cause reactions in the eyes (allergic conjunctivitis), and / or in the lungs (allergic asthma). * Sensitization occurs when the body’s immune system recognizes a substance as foreign and starts to produce allergy antibodies to it. This process can happen without any noticeable symptoms. However, if the sensitised person is re-exposed to the same substance, the immune system may react, releasing chemicals including histamine. This causes inflammation of the inner lining of the nose, resulting in the typical nasal symptoms. AR is very common. Worldwide, it affects between 10% to 30% of the population. Unfortunately, many people remain undiagnosed or misdiagnosed. Although AR can develop at any age, symptoms often develop during childhood/adolescence, peak between age 20 and 40, and then may gradually decline. It is one of the most common long-term conditions in childhood. AR is uncommon in children under 2 years of age, but between the ages of 3 and 12, the number of sensitised children increases steadily. Children are more likely to develop AR if one or both parents are affected by the condition. Terminology ‘Rhinitis’ means inflammation (redness, swelling) of the nasal lining. It is linked to bothersome symptoms such as nasal congestion, sneezing, itching, and mucus dripping down the back of the throat. There are many causes of rhinitis, the commonest being a viral cold, which everyone suffers from time to time. Allergic rhinitis, on the other hand, is caused by allergies to harmless airborne substances. The allergic inflammation can also result in irritability of the nose, so that sufferers react not only to allergens but to other things such as temperature changes, smoke, perfume etc. Sometimes a person with AR with an undiagnosed allergen, like house dust mite, presents with these non-specific reactions and is misdiagnosed as having Non-Allergic Rhinitis (NAR). AR is sometimes called “hay fever”, but this name is confusing. The condition is not caused by contact with hay, and there is no fever. Hay fever typically refers to seasonal allergic rhinitis, but not all allergies are seasonal. Seasonal allergies occur in the spring, summer, and early fall, when pollen counts from trees, grass, and weeds are higher. House dust mites, cockroaches, and animal dander are examples of allergens that are present throughout the year and can cause year-round (perennial) allergic rhinitis. Is it a viral infection or allergic rhinitis? Some symptoms of viral infections and allergic rhinitis are similar, but there are differences to look out for. Condition Symptoms Onset of symptoms Duration of symptoms Allergic rhinitis – Sneezing (often occurring in bouts) and itching of the nose – Clear nasal discharge and/or blocked nose – Can be accompanied by itchy, red and/or watery eyes – Itchy throat/ears/ roof of mouth – Tiredness Usually a trigger, like exposure to pollen, house dust mite or a pet. Symptoms develop immediately on allergen exposure but ongoing exposure (e.g. to pets, house dust mite) may make it more difficult to link exposure with symptom onset. As long as exposure to the allergen continues. They may persist for hours afterwards Common cold – Sore throat, then blocked and/or runny nose (thick and/or coloured discharge) and/or sneezing – Tiredness – Coughing 1 to 3 days after exposure to a cold virus (another sick person) Usually a week or less COVID-19 (coronavirus disease) – Headache – Sore throat – Runny or stuffy nose, sometimes also sneezing – Muscle aches – Tiredness – Sometimes a fever – Sometimes diarrhoea, nausea or vomiting – New loss of taste and/or smell – Coughing 1 to 4 days after exposure to an influenza virus (another sick person) A few days to two weeks, but some experience severe complications, requiring hospitalisation The flu (influenza) – Headache – Cough – Muscle aches – Tiredness – Sore throat – A runny or stuffy nose – Fever or feeling feverish/having chills – Tiredness – Sometimes diarrhoea, nausea or vomiting (more common in children) 1 to 4 days after exposure to an influenza virus (another sick person) A few days to two weeks, but some experience severe complications, requiring hospitalisation The table above is not intended for self-diagnosis, but to help raise awareness of the typical signs of a short-lasting common cold compared with allergic rhinitis. If symptoms persist, it is advisable to discuss them with your doctor to obtain a proper diagnosis and appropriate treatment. Triggers and risk factors Triggers Several substances inside and outside your house can trigger allergic rhinitis. Common triggers are: Pollen from trees, grass, and weeds. Pollens are plant seeds. Tiny, wind-blown pollens are the ones that cause allergy, not those from colourful plants which are insect-spread. House dust mites. These tiny spider-like creatures live in bedding, sofas, carpets, and other woven fabric materials. The mites don’t harm humans directly – they don’t bite – but their droppings can trigger allergies. Animal dander is made up of dried saliva or dead skin cells or scales (similar to dandruff in humans) Pets like cats, dogs and horses are common triggers, but in some people, other animals such as rodents or birds can also cause allergic reactions. Other insects (cockroaches, ladybugs) Mould spores Pollens from trees, grasses, and weeds are the most common cause of seasonal allergic rhinitis. In people that are affected by year-round (perennial) allergic rhinitis, the most common causes are house dust mites, animal dander, cockroaches, and mould. Occupational allergens Occupational allergens can also cause allergic rhinitis. Over 300 agents can cause occupational rhinitis, the same ones which can induce occupational asthma.Some are plant or animal proteins, (flour, latex, laboratory animals). Sensitization can be objectively shown by skin prick testing or a blood test (serum-specific IgE). Other agents cause inflammation of the inner lining of the nose (mucosal inflammation) by non-allergic mechanisms.(e.g di-isocyanates and glutaraldehyde) or via irritation (e.g chlorine and ammonia).