The allergic march describes a common set of allergic conditions, where one can lead on to another as a child ages. This includes eczema (atopic dermatitis), food allergy, hay fever (allergic rhinitis) and asthma. As these are collectively called atopy, it’s sometimes referred to as the atopic march, with one marching into the next like unstoppable soldiers. Allergic conditions often run in families, although it can vary which is most bothersome for each child or adult. First degree relatives – a parent or sibling – make you high risk for developing an allergic condition, and you are at highest risk if both of your parents suffer.
The typical pattern is that eczema appears in babies and toddlers. Dry skin, especially in winter, is common in all babies, but it usually improves in the first year. Eczema is driven by a different process, and can be pronounced through pre-school and primary school. Most grow out of eczema but it persists for some into adolescence and adulthood. Food allergies may become obvious through infancy and pre-school. While cow’s milk protein allergy is common in many children without an atopic tendency, most grow out of this by the age of 5. For those with an atopic tendency, this may persist, and other common allergies may develop, such as allergies to peanuts and tree nuts (like almonds, hazelnuts, cashews and walnuts). Allergic responses can grow with time and exposure in a process called IgE-mediated sensitisation, causing rashes and breathing problems, which can be very serious.
Hay fever is sensitisation to environmental allergens – typically this refers to pollen, but the term allergic rhinitis refers to the same nose and eye symptoms as to other allergens. School-age children may develop allergies to house dust mites and animal fur, among others. It’s rare to see any symptoms before the age of 2. Asthma, an inflammation of the airways that causes cough and wheezing, comes next. It may be a response to an allergen, extremes of temperature, viral infections causing coughs and colds, stress, or occurring without an obvious prompt. Many pre-school children get diagnosed with viral-induced wheeze in response to a virus causing a cold. This can cause anxiety if there’s a history of asthma in the family, however, this does not mean they will go on to develop asthma. Most grow out of it by the age of 5 – and around the same time, they stop getting so many coughs and colds. Asthma more commonly develops later in childhood and in the teens.
The good news is that you can grow out of any or all of these with time – eczema can be confined to infancy, and asthma to childhood, although it’s likely you might always have a sensitivity to certain allergens such as pollen, giving you hay fever symptoms. Anticipating symptoms is key to reducing flares – so for those with eczema, increase emollients as winter comes or when you go swimming; fort hose with hay fever, start antihistamines two weeks before the pollen season, to avoid triggering your usual symptoms. To consider whether we can prevent other atopic conditions from developing after the first, we have to understand the immune system drivers. IgE antibody in our immune system is thought to be a significant player – eczema may be IgE-mediated or not, but IgE-mediated is more common in those with the allergic march. One area of research is IgE sensitisation, which happens as eczema disrupts the skin barrier, allowing environmental allergens in. This makes it more likely a child will develop an IgE response to these, which manifests as asthma and hay fever. So if there is intensive skin barrier maintenance – that is, heavy and frequent application of moisturisers – could this prevent it? There is some evidence of this being of benefit, but more research is needed before they draw definite conclusions. One area of interest is in those at high risk of developing a peanut allergy. Results from the LEAP study showed that regular consumption of peanuts in infancy and continued until 5 years old led to an 81% reduction in later peanut allergy. This was for those infants who already had severe eczema, egg allergy or both. From other studies, most experts suggest peanuts should be introduced by the age of 6 months for all children, although you should avoid whole peanuts as they can cause choking in infants.
You should see your doctor for any of these atopic conditions that are not improving with your home treatment or if they are causing your baby or child significant distress and disturbing sleep. This includes any red, itchy rash, especially if it’s crusty, weeping or sore, as this can indicate eczema or infected eczema. For any breathing difficulties – coughing or wheezing, especially at night, or getting more out of breath running around than friends or siblings – these require urgent attention from your doctor. They may do further tests before diagnosing asthma, and they can prescribe medications to help. If your child has asthma, they will have a tailor-made programme to allow them to live as active a life as possible. Any suspected food allergies need specialist attention. See your doctor, who can discuss any symptoms and refer your baby or child to a paediatric service or allergy clinic. Don’t try any allergen exposure techniques without specialist supervision, as this can be dangerous.