If you deal with eczema, you know how challenging it can be to resist the urge to scratch those unbearably itchy patches on your skin. Sure, scratching might give you some short-term relief but you know it will only make you feel worse in the long run. Eczema can be difficult to manage and you’ve probably wondered on more than one occasion what causes eczema. But first, it’s important to understand what eczema is.
There are different types of eczema, but atopic dermatitis is the most common form, affecting about 10% of the U.S. population, according to the National Eczema Society. Eczema is most often diagnosed in children, but plenty of adults have it too. In fact, as many as one in four people with eczema may be diagnosed in adulthood, and that number appears to be on the rise, according to a 2019 study published in the Journal of Allergy and Clinical Immunology: In Practice.1
While receiving an eczema diagnosis is pretty common, getting to the bottom of what causes eczema is not so clear-cut. Researchers are still working to understand the disease’s exact mechanism; in the meantime, there’s plenty they do know about possible eczema causes and what triggers flare-ups. Here, dermatologists break down everything you need to know.
First, what are the most common eczema symptoms?
Before we talk about all the possible reasons you have eczema, it’s good to recognize the signs and symptoms. Eczema tends to affect the folds of the skin, including the bends of the elbows and knees, ankles, wrists, eyelids, and the back of the neck. According to the Mayo Clinic, common eczema symptoms can include:
- Dry, itchy skin
- Inflammation on the skin that may appear red, purple, or brownish
- Raw, cracked, swollen, or scaly skin
- Small, raised bumps
While you may experience one or all of these symptoms, it’s important to note that eczema can present differently from person to person depending on your skin tone. “Different ethnic populations have different presentations and patterns of eczema,” Azeen Sadeghian, MD, FAAD, board-certified dermatologist in Baton Rouge, Louisiana, and fellow of the American Academy of Dermatology, tells SELF. For example, if you have a deeper skin tone, your inflammation may take on a violet or purple color (instead of looking pink or red as it typically would in lighter skin tones). And over time, you may also see some skin discoloration if your eczema is left untreated.
What’s more, Black people will sometimes develop eczema on the outside of the forearms or elbows as opposed to the inside folds of the skin, Dr. Sadeghian notes. Follicular accentuation—where the skin around hair follicles becomes pronounced and bumpy—is also a more common symptom in darker skin tones. These important nuances can sometimes present challenges when it comes to diagnosing skin conditions in people of color.
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What causes eczema?
The underlying causes of eczema are complicated, Dr. Sadeghian says: “Our skin cells are normally like a brick wall barrier that’s covered with a varnish to protect it.” But when someone has eczema, this metaphorical varnish doesn’t function the way it should, leaving the bricks—or in this case, skin cells—more vulnerable to an invasion.
As a result, your skin becomes highly sensitized to any irritant, allergen, or environmental factor that might compromise it. And, as Dr. Sadeghian explains, any damage done to your skin barrier causes more inflammatory cells to gather in the affected area, creating a chain reaction that plays out in the form of eczema.
Researchers don’t know why some people are more susceptible to eczema than others but, according to the American Academy of Dermatology, the following factors can increase your risk:
Family history
Genetics is a big determining factor for whether or not you will develop eczema. “If it runs in your family, you’re more likely to get it,” Amy Kassouf, MD, a Cleveland Clinic-affiliated, board-certified dermatologist who practices in Twinsburg, Ohio, tells SELF. A study published in Clinical and Experimental Allergy that followed 4,089 newborns until age four found that 27% of the babies with parents who had eczema developed the condition. Among children who had one parent with eczema, nearly 38% were diagnosed, and when both parents had eczema, 50% of the children ended up having it.2
Genetic mutations
In 2020, a study published in Nature Communications showed that two relatively common variations in a specific gene (the KIF3A gene to be exact) may lead to a weakened skin barrier, which then allows for increased water loss from your skin.3 The researchers theorized that these gene variations make people who have them more prone to developing eczema, per the National Institutes of Health.
A protein deficiency
More than half of people who have eczema may have low levels of a protein called filaggrin, according to the National Eczema Society. Filaggrin acts as a natural moisturizer that helps your skin fend off pathogens (like a virus, bacteria, or other microorganisms). Going back to the brick wall analogy, people whose bodies don’t manufacture enough filaggrin will be more vulnerable to immune system invaders and less protected by their skin.
Dry skin
Dry skin is one of the primary culprits that cause eczema. “Your skin is meant to be a barrier to the outside world. But sometimes it starts to break down, either because of its inability to lubricate itself or because you’re not moisturizing or hydrating enough,” Dr. Kassouf says. Some people have skin that’s naturally prone to dryness, while others have skin that grows dry due to repeated exposure to harsh chemicals or irritants.
Allergies
Allergies don’t cause eczema, but these two conditions are closely related. Eczema is often found in people who also have hay fever and asthma, Dr. Kassouf says, forming what medical professionals call the atopic triad. In this disease progression, known as the atopic march, infants and young children will develop eczema symptoms, and then later progress to have asthma and allergic rhinitis. Researchers, who published a 2014 study in the Journal of Clinical and Cellular Immunology, hypothesized that the weakened skin barrier could be the reason infants with eczema become young adults with allergies.4