Dermatologists have been aware of an association between eczema and other health concerns. Now, after evaluating data from numerous studies, the American Academy of Dermatology (AAD) has produced an official guideline, which was released at the beginning of the year. The analysis, published in the Journal of the American Academy of Dermatology in January, found strong evidence tying atopic dermatitis in adults to a number of diseases and conditions, including hay fever, asthma, and food allergies; alopecia (sudden hair loss) and chronic urticaria (hives); osteoporosis; mental health disorders like depression; and skin infections. When it comes to substance abuse disorder, ADHD (attention deficit hyperactivity disorder), and metabolic syndrome (a group of five conditions that can lead to heart disease, diabetes, stroke, and other health problems), study authors identified some evidence linking these issues to eczema. The report also suggested a link between atopic dermatitis and various cardiovascular issues, but this association was considered to be small. Evidence supporting a link between eczema and autism spectrum disorders, heart attack, and stroke was inconclusive. “We are realizing more and more that inflammatory skin disease — such as atopic dermatitis and psoriasis — are not only skin conditions, but rather affect the entire person,” says Dr. Davis. “So we need to practice whole-person care. This guideline is created to empower patients, and to empower the medical community to help patients better address their skin needs.”

For decades, dermatologists have recognized a connection between eczema and other atopic and allergic conditions. (The word “atopic” itself indicates an association with allergies.) MedlinePlus says that up to 60 percent of people with atopic dermatitis develop asthma or hay fever (allergic rhinitis) later in life, and up to 30 percent have food allergies. Eczema can often signal the beginning of a progression of allergic diseases known as “atopic march” or “allergic march.” After people develop eczema, a typical pattern is for them to develop food allergies, followed by hay fever and then asthma. This new AAD guideline found that about a quarter of adults with eczema had asthma, and they were three times more likely to have this inflammation of the airways than the general population. The research also spotlighted evidence suggesting that asthma in children ages 7 to 11 was linked to a more persistent type of eczema. Targeted biologic therapies such as dupilumab (Dupixent) demonstrated a potential benefit for both severe atopic dermatitis and asthma. “Dupilumab has been approved for asthma and eczema because both of these diseases kind of work through the same pathway and cause inflammation,” says Karan Lal, MD, the committee chair for the Society for Pediatric Dermatology. “It’s possible if we’re treating eczema with dupilumab at a very early age, we may prevent [children] from developing clinical signs of asthma.” When it comes to food allergies, researchers estimated that just over 1 in 10 individuals with eczema were likely to have this condition. While the researchers were unclear as to what the implications may be, they pointed out that patients often ask whether food allergies are a trigger for their eczema and whether they should seek out testing for food allergies. The AAD team observed a consistent link between allergic rhinitis (hay fever) and eczema but little data showing a relationship to allergic conjunctivitis (inflammation of eye tissue) and eosinophilic esophagitis (inflammation of the esophagus). “We always suspected and knew in practice that asthma, food allergies, and other atopic diseases such as allergic rhinoconjunctivitis were more common in patients with eczema, but now we have research data to support those conclusions,” says Davis.

Davis stressed that the study confirmed that certain skin diseases are more common in atopic dermatitis patients, such as alopecia areata — an autoimmune disease in which the immune system attacks hair follicles, causing sudden hair loss that often results in bald patches on the head and that can affect the hair on other parts of the body as well. The guideline presented data demonstrating a strong association between eczema and the autoimmune condition chronic urticaria (hives). Overall, if you have eczema, you’re 2.5 times more likely to have an autoimmune condition, according to the new guideline.

An analysis that pooled four studies, including 11,244 adults with eczema and 149,713 people without the condition, found that individuals with eczema faced double the odds of self-reported or clinician-diagnosed depression. In addition, researchers found that eczema patients were more likely to consider suicide, but evidence linking the condition to actual death by suicide was weak. As to why these patients may be more apt than the general public to have mental health issues, the AAD panel believes that itching, poor sleep, and decreased quality of life overall may play an extensive role. Although some research made a connection between substance abuse and eczema, evidence was limited about any tie between the skin condition and alcohol use or cigarette smoking. Davis and her collaborators underscored that ADHD and autism spectrum disorders are better studied in children rather than adults, and these connections will be explored more in depth in an upcoming pediatric guideline.

Atopic disease patients have increased levels of blood proteins connected with cardiovascular risk. Because systematic inflammation is an established risk factor for cardiovascular disease, it’s possible that treatments that manage inflammatory skin diseases like eczema could decrease the likelihood of heart problems, according to the guideline. But in general, the research found only a slight link between eczema and hypertension, peripheral and coronary artery disease, congestive heart failure, and events such as myocardial infarction and cardiovascular death. The data suggested a small association between eczema and obesity and dyslipidemia (an imbalance of lipids such as cholesterol). Still, pooled facts from eight cross-sectional studies revealed that eczema patients were 36 percent more likely to be obese and 13 percent more likely to have high cholesterol than the general population. The guideline authors pointed out that atopic dermatitis may actually have an inverse relationship with diabetes, with some research suggesting that individuals have a lower risk of diabetes overall and type 2 diabetes specifically. Based on data analyzed in this paper, however, Davis emphasized that patients with eczema may face a greater likelihood of metabolic syndrome as a whole.

Davis and her team highlighted an investigation demonstrating an increased risk of osteoporosis among those with eczema, and a separate study showed a heightened likelihood of bone fracture. For those with severe atopic dermatitis, the possibility of fracture due to osteoporosis was even greater. Investigators noted that more research is needed to understand the mechanisms behind this association, but some explanations suggest that chronic systemic inflammation may have a negative effect on bone metabolism, leading to increased bone loss.

The connection between eczema and staphylococcal skin infections is well known. The guideline spotlights a study from the United Kingdom indicating that herpes superinfection is twice as common among those with eczema. Other data suggested cutaneous infections, bacterial skin infections, and eczema herpeticum (a painful, blistering rash caused by the herpes simplex virus) are all more likely to occur among people with eczema.

Will the Guideline Change How Dermatologists Treat Their Eczema Patients?

While Golara Honari, MD, a dermatologist with Stanford Medicine, sees the value in raising awareness about eczema’s link to other diseases, she believes patients and doctors need to interpret these correlations with caution. “We need to learn more about these conditions in relation to atopic disease,” says Dr. Honari, using cardiovascular disease as an example. “There are other common skin diseases — for example, psoriasis — that have really solid evidence for increased risk of cardiovascular disease, but for atopic dermatitis, that evidence is still not very solid.” “We’re putting together associations, but we have to be careful, because I don’t think these associations necessarily lead to clinical correlations,” adds Dr. Lal. “Do the results in the guideline mean that for patients that come in, I have to screen all my patients for metabolic syndrome because they have a diagnosis of eczema? It doesn’t really work like that.” Overall, Davis and her colleagues view the new guideline as a tool to educate and empower — and not induce fear. “When we know certain diseases are interrelated, then we can work on monitoring for those diseases and screening for them, and we can work on lifestyle modification factors that can alter the risk of a disease course,” she says.