Eczema and asthma have more in common than their last two letters–they often can both occur in the same person.
While it seems unfair that one person can have two chronic conditions at the same time, eczema and asthma are related. What links them is an immune system that is too sensitive. Both conditions can be caused by an over-reactive immune system that starts with inflammation in the skin, in the case of eczema, or in the lungs, in the case of asthma.
The Atopic Triad
If it weren’t bad enough that eczema and asthma are linked, a third condition can also be present. Eczema and asthma are two parts of what is called the atopic triad or the allergic triad. The classic triad is a combination of atopic dermatitis (eczema), asthma, and allergies such as allergic rhinitis (hay fever) or food allergies. Some people have only one, some have two, and some have all three of these conditions.
“Atopic” means hypersensitivity and refers to a general tendency for developing allergic diseases.
Both asthma and eczema are very common. According to the National Eczema Association, more than 31 million people in the United States, or about 10%, have some form of eczema. According to the Asthma and Allergy Foundation of America, about 25 million people in the United States have asthma.
Genes and Triggers
There are many factors or triggers in the environment that can set off a flare of eczema or an asthma attack. These triggers can be contact allergens, stress, certain foods, and the presence of pollen and dust mites. The humidity and temperature of the air can also set off either eczema or asthma.
Eczema, asthma, and allergies tend to run in families, which points to an underlying genetic cause. Even though genes may have created the over-reactive immune system, all three conditions may be variable in their severity due to the presence or absence of allergens and other environmental factors. In other words, a person’s genes may have set them up to have eczema or asthma, but they must also be exposed to the environmental trigger.
Although these conditions may run in families, not all members may have the same conditions, with some having eczema and others having allergic rhinitis or asthma.
In the case of eczema, or atopic dermatitis, the immune system overreacts to anything that irritates the skin. The irritated skin becomes inflamed, red, and itchy. It may become leathery and scaly, or swollen. People with eczema often have overly sensitive skin that is very dry with an epidermis that isn't as strong as it should be to perform as a good barrier against the environment. The poor nature of this barrier means that the skin is more susceptible to allergens such as smoke, dust mites, and pollen.
There are several skin conditions that are called eczema, including atopic dermatitis, contact dermatitis, dyshidrotic eczema, nummular eczema, seborrheic dermatitis, and stasis dermatitis. Some, such as atopic dermatitis, which is the most common form of eczema, are more closely linked with an over-reactive immune system than others.
In the case of asthma, the airways of the lungs become inflamed by irritants, which causes them to swell and narrow, and to spasm. During an asthma attack, the lungs also create more mucus, which can clog the already narrowed airways. This restricts breathing and may cause symptoms like shortness of breath, wheezing, coughing, and a feeling of tightness in the chest.
Asthma can vary greatly in severity, with some people having symptoms every day while others only having some wheezing a few days a year. People with severe asthma may have breathing difficulties seriously enough that it limits their activities. On average, about 10 people in the United States die from severe asthma attacks each day. Uncontrolled asthma can also permanently damage the lungs.
Common environmental triggers for asthma include pollen, cigarette smoke, animal dander, and air pollution. Triggers for asthma also include stress, cold air or extreme weather changes, and exercise.
Take note of the fact that some of the triggers for eczema and asthma are the same, like smoke, air pollutants, and pollen. Both eczema and asthma can also be made worse by weather conditions and stress.
Another link between eczema and asthma is that both can be accompanied by food allergies and can be exacerbated by food triggers. There is also some evidence that the imbalances in the microbiome of the digestive system—the gut microbiome—may play a role in eczema and asthma.
The Cellular Response
When someone with asthma inhales a trigger, a type of immune cell in the airways (called an antigen-presenting cell) identifies it and alerts other immune cells. Normally, a type of T helper cell called T helper 0 stops an immune system from overreacting by telling other cells to stop responding. In people with asthma, these helper T cells change into T helper 2 cells which start up the immune response against the trigger instead of stopping it. This over-reaction leads to inflammation, spasms of the airway, and excess mucus production.
In eczema, something similar happens. An allergen or irritant triggers the immune reaction in the skin and instead of T helper cells that help shut down or modulate the immune response, there is a predominance of T helper 2 cells that rev up the immune response.
Researchers are also exploring a link between eczema and the skin microbiome. The skin microbiome is the ecosystem made up of trillions of bacteria, fungi, and viruses that live on your skin’s surface—some good, some bad. When the bad bacteria outweigh the good, the skin microbiome becomes unbalanced. We now know that the majority of eczema cases are linked to an unbalanced skin microbiome though thankfully, there are solutions to this.
It Starts Early
Both eczema and asthma can start in childhood or even shortly after birth. Many children with eczema or asthma tend to get better as they get older, but they don’t always actually grow out of the conditions, or at least not completely. Although most people may have fewer and less severe episodes of eczema and/or asthma as they mature, they could still generally have overly sensitive skin and lungs for the rest of their lives.
Although early symptoms are common, people who have never had either eczema or asthma can develop either condition as adults.
Whether you have eczema or asthma or both, learning to understand these conditions can help you deal with them. Learning what triggers an outbreak of eczema or an asthma attack can help you live your best life.