Dealing with atopic dermatitis (AD) can be tough. There are the symptoms of a chronic skin condition — dry skin, itching, skin rashes, and more. On top of that, many people who have AD also experience other allergic conditions, as well as asthma.

Sixty percent of people with atopic dermatitis will later have asthma or allergic rhinitis (commonly known as hay fever), and 30 percent go on to develop food allergies. This progression of conditions — from AD to other allergies and asthma — is known as the “atopic march.”

What Is the Atopic March?

The atopic march is strongly associated with atopic dermatitis in infants and very young children. One study found children who had atopic dermatitis were almost three times more likely than children in the general population to have developed allergic rhinitis and asthma at a five-year study follow-up.

Studies have found that the likelihood of AD leading to these other conditions increases with the severity of AD. For example, studies have found that around 20 percent of children with mild AD go on to develop asthma. By comparison, nearly 70 percent of children with severe AD go on to develop asthma at some point in their lives.

Studies have found that the likelihood of AD leading to allergies or asthma increases with the severity of AD.

There is little research on how and whether the atopic march affects people who develop AD as adults. Most people with AD first experience the condition in early childhood.

What Causes the Atopic March?

Researchers still aren’t sure why some people develop atopic conditions, but several different risk factors are likely involved. These factors may increase a person’s risk of developing AD.

Genetic Factors

People with atopic dermatitis often report having a family history of the condition, and unsurprisingly, many cases of AD have a genetic link. Up to 50 percent of people with AD have changes in a gene linked to filaggrin. Filaggrin is a protein that helps form the outer layer of the skin, known as the epidermis, and it plays a key role in keeping the skin barrier intact and maintaining hydration. These gene variants result in difficulties producing filaggrin, making the skin more sensitive and prone to inflammation — and this eventually causes AD because barrier dysfunction results in the inability to retain moisture. Although not every child with AD will have these gene variants, those who do are more likely to have flare-ups and need stronger treatments, such as topical steroids.

These gene mutations (changes) are also associated with an increased risk of developing asthma and allergies, but only in people who have previously experienced AD. Researchers think people with AD are more likely to develop allergies and asthma because allergens in the environment enter through breaks in AD-inflamed skin.

Researchers think people with AD are more likely to develop allergies and asthma because allergens in the environment enter through breaks in AD-inflamed skin.

This process is often referred to as the dual allergen hypothesis, by which skin exposure to allergens can result in food allergies. According to this theory, exposure to allergens by breathing or inhaling them might also play a role in the development of food allergies, but it’s less clear whether this is related to AD.

Once allergens enter the skin, they interact with immune cells in the epidermis and the dermis (the layer beneath the epidermis). This causes sensitization — the process by which the body produces excess immunoglobulin E (IgE) antibodies. As a result of this immune system response, people can develop allergies and also other conditions, like hay fever and asthma.

Environmental Factors

Atopic conditions — such as asthma, AD, and other allergies — have been on the rise worldwide. Several environmental factors might be to blame. The hygiene hypothesis states that better standards of hygiene may lead to more cases of atopic conditions. In the past, childhood exposure to lots of dirt, grime, and infections may have helped kids develop more tolerant immune systems. Additionally, some research suggests that children who grow up on farms around animals, plants, and dirt are more resistant to allergies and asthma. Research has also shown that spending time on farms during pregnancy can help promote the maturity of the baby’s immune system.

Early childhood use of certain medications, especially antibiotics, may be increasing the worldwide rates of atopic conditions. Rising rates may also be caused by a lack of vitamin D and increased obesity rates, according to the American Academy of Allergy, Asthma & Immunology.

Do Atopic Conditions Have Treatments in Common?

Because atopic dermatitis, allergies, and asthma all involve the same underlying immune system response, some treatments that work to ease AD may also treat asthma and allergy symptoms.

Antihistamines

Antihistamines work to block the effects of histamine, a chemical released by the immune system. Excess histamine can contribute to the symptoms associated with allergic rhinitis and asthma, such as wheezing, trouble breathing, coughing, and a runny nose. Excess histamine also triggers the skin symptoms associated with AD, such as itching. It can also cause hives, which are red, raised spots on the skin that itch and may burn.

Antihistamines are sometimes used as an add-on treatment for AD. Their anti-itch effects may stop a vicious cycle in which scratching further inflames the skin, creating more itching. However, there’s mixed evidence for antihistamines’ effectiveness against AD itching. A 2019 review of studies found that taking antihistamines had little to no effect on how people with atopic dermatitis assessed their itch levels.

Some antihistamines can cause sleepiness and are best used for cases of itching at night. For some people with AD, this may be beneficial as it can support improved sleep, which is often an issue for people with AD. Finally, topical antihistamines should be avoided for AD, as they can worsen skin inflammation. According to the latest guidelines, it is better to use antihistamines that don’t cause drowsiness, as those that do can make it harder for some people to work and go about their daily lives.

Corticosteroids

Corticosteroids are commonly used to treat atopic dermatitis, other allergies, and asthma symptoms. Corticosteroids perform the same function as cortisol, a hormone the body creates in response to stress. Corticosteroids calm immune responses and the accompanying inflammation.

Corticosteroids come in different forms, such as tablets, inhalants, and topical creams and gels. Someone with environmental allergies might use a corticosteroid nasal spray to reduce sneezing and nasal drip. Corticosteroid inhalers are useful for asthma.

People with AD usually use corticosteroid creams applied directly to the skin in the form of a cream, ointment, lotion, or spray. Topical corticosteroids can cause skin thinning, acne, rashes, and stretch marks. Due to these and other potential long-term side effects, steroids should not be used daily for more than two to four weeks in a row. Therefore, frequent short-term usage of topical corticosteroids is preferred to treat the flares of eczema.

Corticosteroid tablets and injections are often called systemic corticosteroids. Systemic corticosteroids can be used to treat asthma and AD, although there is debate about how often they should be used for these conditions due to the risk of infection, weight gain, and bone density loss, among other side effects. Systemic corticosteroids should be reserved for AD cases in which there are no other treatment options or immediate flare-up relief is needed because long-term use of oral corticosteroids can lead to many complications.

Biologics

Biologics are a class of medications made from proteins that are specially created in a lab to treat certain diseases. They work by targeting immune cells or molecules associated with inflammation. Biologics may be prescribed when standard medications are not effective in controlling AD or severe asthma.

Biologic drugs approved by the U.S. Food and Drug Administration (FDA) for atopic dermatitis or severe asthma include:

• Reslizumab (Cinqair) for asthma
• Dupilumab (Dupixent) for AD and asthma
• Benralizumab (Fasenra) for asthma
• Mepolizumab (Nucala) for asthma
• Omalizumab (Xolair) for asthma

Dupilumab in particular has been helpful for people with severe AD, as it can allow for symptomatic management without the stronger immunosuppressive side effects associated with prior medications.

Biologics are injectable drugs. Common side effects of dupilumab include conjunctivitis (pink eye), cold sores, and infections at the injection site.

Why Is the Atopic Connection Important?

Not everyone with atopic dermatitis will develop other allergic conditions or asthma. However, understanding the connection between the three conditions — and recognizing AD as a risk factor for the development of the other two — is important. If you or your child has AD, you can monitor for the development of allergies and asthma. Early diagnosis and treatment for asthma and allergies can help manage and control symptoms.

Symptoms of asthma include:

• Wheezing
• Chest pain or tightness
• Shortness of breath
• Coughing

All of these may be worse at night or after exercise.

Symptoms of allergies can include:

• Sneezing
• Itchy face
• Runny or stuffy nose
• Red, swollen, or watery eyes
• Tingling in the mouth
• Swelling of the mouth, lips, tongue, or throat
• Hives

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