Atopic dermatitis, often called eczema, is a long-lasting skin condition that brings dry, itchy, and inflamed skin to millions of people around the world. This common inflammatory disorder can affect anyone at any age, though it most often begins in early childhood, leaving many families searching for ways to manage its unpredictable flare-ups and ease the discomfort it brings.

Epidemiology

Atopic dermatitis is remarkably common, touching the lives of a significant portion of the population worldwide. Current estimates suggest that the condition affects approximately 10 to 30 percent of children and between 2 and 10 percent of adults in developed countries^[6]. In the United States alone, about 17.8 million people are living with atopic dermatitis, with many cases remaining undiagnosed^[3]. More specifically, over 9.6 million children under the age of 18 and about 16.5 million adults in the U.S. are affected by this condition^[5].

The prevalence of atopic dermatitis has been rising over recent decades. Studies indicate that the number of cases has increased two to three-fold in many parts of the world^[6]. This increase has been particularly noticeable in developed nations, suggesting that modern lifestyles and environmental factors may play a role. Interestingly, the condition is more common at higher latitudes, which researchers believe may be connected to reduced sun exposure and lower humidity levels in these regions^[6].

Atopic dermatitis most commonly begins during infancy and early childhood. The condition typically appears very early in life, with approximately 60 percent of cases starting before the child reaches one year of age, and 90 percent of cases beginning by the time the child turns five^[6]. While it’s often thought of as a childhood disease, atopic dermatitis can continue into adulthood or even appear for the first time in adult years. The condition affects both males and females, though females are affected slightly more often than males^[10].

When looking at the natural course of the disease, many children will see improvement as they grow. About 60 percent of children who develop atopic dermatitis will find that their condition resolves by the time they reach 12 years of age^[6]. However, this also means that a substantial number of people continue to experience symptoms throughout their lives, making atopic dermatitis a chronic condition for many individuals.

Causes

The exact cause of atopic dermatitis remains unknown, but researchers understand that it develops from a complex combination of genetic, immune system, and environmental factors working together^[1][2]. This isn’t a simple disease with a single cause, but rather a condition where multiple factors contribute to its development and persistence.

At the heart of atopic dermatitis is a problem with the skin’s protective barrier. Our skin normally acts as a shield, keeping moisture in and harmful substances out. In people with atopic dermatitis, this barrier doesn’t work properly^[2]. A key player in this barrier problem is a protein called filaggrin, which is essential for maintaining healthy skin structure. Filaggrin helps form the outermost layer of skin and breaks down into natural moisturizing factors that keep skin hydrated^[6].

Many people with atopic dermatitis have mutations in the gene responsible for producing filaggrin. These genetic alterations are present in up to 30 percent of people with the condition^[6]. When the skin lacks sufficient filaggrin, moisture escapes more easily, and the skin becomes dry and vulnerable. More importantly, this weakened barrier allows irritants, allergens, and bacteria from the environment to penetrate the skin more easily, triggering inflammation and immune system reactions.

The immune system also plays a crucial role in atopic dermatitis. People with this condition have an overactive immune response. When the weakened skin barrier lets in allergens or irritants, the immune system responds by producing inflammation. This inflammation causes the redness, swelling, and itching that characterize the condition. The immune system dysfunction also involves elevated levels of immunoglobulin E (IgE), an antibody associated with allergic reactions^[8].

Genetics strongly influences who develops atopic dermatitis. If one parent has an atopic condition (which includes atopic dermatitis, asthma, or hay fever), there is more than a 50 percent chance that their children will develop atopic symptoms. If both parents are affected, up to 80 percent of their offspring will be affected^[6]. The condition also shows strong concordance in identical twins: if one identical twin has atopic dermatitis, the other has an 85 percent chance of having it as well^[10].

Risk Factors

Several factors increase a person’s likelihood of developing atopic dermatitis. Understanding these risk factors can help identify who might be more vulnerable to the condition, though having risk factors doesn’t guarantee someone will develop it.

Family history stands as the strongest risk factor for atopic dermatitis. If one or both parents have atopic dermatitis, or if close family members have asthma or hay fever, children in that family face a much higher risk of developing the condition^[4]. This familial pattern reflects the strong genetic component of the disease.

Living environment also influences risk. People who live in cities are more commonly affected than those in rural areas^[1][2]. Similarly, those living in dry climates face increased risk^[1][2]. The higher prevalence in urban settings may relate to increased exposure to pollution, allergens, and other environmental factors that stress the immune system. The association with dry climates makes sense given that atopic dermatitis fundamentally involves problems with skin moisture and barrier function.

Food allergies create another connection. Between 10 and 30 percent of people with atopic dermatitis have food hypersensitivity that can cause or worsen their skin condition. The most common culprits are eggs, milk, peanuts, soy, and wheat, which together account for 90 percent of food-related reactions or flares^[6]. However, it’s important to note that not everyone with atopic dermatitis has food allergies, and dietary restrictions should only be implemented under medical guidance.

Recent research has also found an association between smoking and adult-onset atopic dermatitis^[6]. This suggests that tobacco exposure may contribute to developing the condition later in life, adding to the many health reasons to avoid smoking.

Age represents a significant risk factor, with atopic dermatitis being most likely to begin in very young children. The condition typically starts before age two, though it can appear at any point in life^[1][3]. Children who develop atopic dermatitis are also at higher risk for developing other allergic conditions as they grow, including food allergies (15 percent versus 4 percent in children without atopic dermatitis), asthma (25 percent versus 12 percent), and allergic rhinitis (34 percent versus 14 percent)^[13].

Symptoms

The hallmark symptom of atopic dermatitis is intense itching. This pruritus, as doctors call it, is actually the only symptom of atopic dermatitis, though it leads to various visible changes in the skin^[8]. The itching can be so severe that it disrupts sleep, interferes with daily activities, and significantly impacts quality of life. Many people describe this itch as relentless and impossible to ignore.

The physical appearance of atopic dermatitis varies considerably from person to person and can look different depending on your skin tone. The condition causes dry, cracked skin that may become red, purple, brown, or gray^[1][2]. For people with light skin tones, affected areas typically appear red. For those with darker skin tones, the rash may look darker than the surrounding skin, or take on brown, purple, or gray hues^[2][4].

The rash associated with atopic dermatitis includes several characteristic features. The skin becomes dry, scaly, and rough to the touch. Small, raised bumps may form, and on brown or Black skin, these bumps are particularly noticeable^[1]. The affected skin may ooze clear fluid and form crusts, especially when scratched or infected^[1][3]. Over time, repeated scratching causes the skin to thicken, a process called lichenification, where skin markings become more prominent and the texture becomes leathery^[3][8].

The location of atopic dermatitis changes with age. In infants and very young children, the rash typically appears on the face and then spreads to the neck, scalp, hands, arms, feet, and legs^[3]. It can cover large areas of a baby’s body. As children grow older, the distribution shifts to where the skin bends and flexes. Common locations include the inside of the elbows, behind the knees, and around the neck^[1][3]. These areas where skin folds and rubs against itself seem particularly vulnerable to developing the rash. In adults, the hands and feet are commonly affected, though the condition can appear anywhere on the body^[3].

Another symptom that often develops is darkening of the skin around the eyes^[1]. Some people also experience swelling in affected areas. The skin may develop small, fluid-filled blisters or show signs of crusting^[2].

The course of atopic dermatitis is typically unpredictable. The condition follows a pattern of flares and remissions. During a flare-up, symptoms worsen significantly, with increased itching, more visible rashes, and greater discomfort. These flare-ups may occur for unexplained reasons, or they may be triggered by specific factors^[8]. Between flares, the skin may improve considerably or even appear nearly normal. This cyclical nature means that people with atopic dermatitis often experience good days and bad days, with symptoms that can change from one time period to the next.

The constant urge to scratch creates what dermatologists call the “itch-scratch cycle.” The skin itches, so you scratch it, but scratching damages the skin barrier further and increases inflammation, which causes more itching^[3]. Breaking this cycle is one of the key challenges in managing the condition. Scratching can also break the skin open, increasing the risk of bacterial infections, which add another layer of complexity to the symptoms.

Prevention

While you cannot completely prevent atopic dermatitis if you have a genetic predisposition to it, there are several strategies that can help reduce the frequency and severity of flare-ups. Prevention in the context of atopic dermatitis focuses on protecting the skin barrier, avoiding triggers, and maintaining overall skin health.

Moisturizing stands as the cornerstone of prevention. Regular, liberal use of emollients (moisturizing products) is recommended for everyone with atopic dermatitis^[3][13][14]. These products help restore the skin barrier and lock moisture into the skin, preventing the dryness that characterizes the condition. Applying moisturizer at least twice daily, and ideally whenever the skin feels dry, helps maintain skin integrity. The best time to apply moisturizer is immediately after bathing, when the skin is still slightly damp, as this helps seal in the water from the bath or shower.

Bathing practices play a crucial role in prevention. Contrary to old beliefs that people with atopic dermatitis should bathe infrequently, current evidence suggests that bathing once a day (or even twice daily for some people) is actually beneficial^[23]. However, the way you bathe matters significantly. Use lukewarm water rather than hot water, and limit bathing time to five to ten minutes^[13]. Hot water and long soaks can strip away natural oils and dry out the skin further. After bathing, pat the skin dry gently rather than rubbing it, which can irritate the skin.

Choosing the right cleansing products is equally important. People with atopic dermatitis should use soap-free cleansers or bath oils designed for sensitive skin^[13][14]. Traditional soaps can be harsh and irritating. It’s also essential to use fragrance-free products, as fragrances are among the most common causes of contact allergies^[14]. Products containing essential oils, despite their natural appeal, should be avoided because they carry a high risk of causing sensitization.

Identifying and avoiding personal triggers represents another key prevention strategy. Many things can trigger flare-ups in people with atopic dermatitis. Heat is a common trigger for most people with the condition. Keeping the home and bedroom cool, avoiding overheating from excessive clothing or bedding, and using cool compresses can help prevent heat-related flares^[14]. Stress also triggers symptoms in many people, so finding ways to manage stress through relaxation techniques, adequate sleep, and mental health support can help prevent flares^[4][23].

Environmental irritants should be minimized. This includes exposure to harsh detergents, rough fabrics (especially wool), clothing with rough seams or labels, and household chemicals^[2][14]. Washing new clothes before wearing them and choosing soft, breathable fabrics like cotton can help. For cleaning, using gentle, fragrance-free laundry detergents and avoiding fabric softeners may reduce irritation.

Temperature changes, particularly exposure to cold weather, can worsen atopic dermatitis for some people. In cold months, using a humidifier to add moisture to dry indoor air can help. Protecting skin from cold wind by covering exposed areas and continuing to moisturize regularly becomes especially important during winter.

For some people, allergens such as animal dander, house dust mites, pollens, and grasses can trigger symptoms^[14]. If testing identifies specific environmental allergies, taking steps to reduce exposure to these allergens may help. However, not all people with atopic dermatitis have allergies, and unnecessary restrictions should be avoided.

While food allergies can affect some people with atopic dermatitis, dietary restrictions should be minimized and only implemented with guidance from specialists^[14]. Unnecessarily restrictive diets can lead to nutritional problems, especially in growing children. If you suspect that certain foods worsen symptoms, proper allergy testing and dietary advice from healthcare professionals is essential before making changes.

Pathophysiology

Pathophysiology refers to the changes that occur in normal body functions when disease is present. In atopic dermatitis, these changes involve complex interactions between the skin barrier, immune system, and environmental factors that work together to create the condition’s characteristic symptoms.

The foundation of atopic dermatitis lies in a defective skin barrier. The outermost layer of skin, called the epidermis, normally functions as a protective shield. This barrier prevents water from escaping from inside the body and blocks harmful substances from entering. In people with atopic dermatitis, this barrier is compromised due to genetic defects, particularly mutations in the gene that produces filaggrin^[3][5].

Filaggrin is a protein that plays a critical role in forming and maintaining the skin barrier. It helps organize other proteins in the outer layer of skin and breaks down into natural moisturizing components that keep skin hydrated^[13]. When someone has only one functioning copy of the filaggrin gene instead of the normal two copies, their skin can form an adequate barrier initially, but the ability to repair damage to that barrier becomes limited^[6]. This means that when the skin is exposed to irritants or experiences minor damage, the repair process doesn’t work as effectively as it should.

Once the skin barrier becomes disrupted, several things happen. First, moisture escapes from the skin more easily, leading to the characteristic dryness and scaling seen in atopic dermatitis. Second, substances from the environment—including allergens, irritants, and bacteria—can penetrate through the weakened barrier more easily. This is where the immune system becomes involved.

When environmental allergens pass through the damaged skin barrier, they encounter immune cells in the deeper layer of skin called the dermis^[3]. In people with atopic dermatitis, the immune system is dysregulated and overreactive. Instead of mounting a measured response, the immune system produces excessive inflammation. This inflammation manifests as the redness, swelling, heat, and pain that characterize active atopic dermatitis lesions.

The immune dysfunction in atopic dermatitis involves several abnormalities. People with the condition often have elevated levels of immunoglobulin E (IgE), an antibody typically involved in allergic reactions^[8]. They may also have increased numbers of certain white blood cells called eosinophils in their blood^[8]. These immune system changes contribute to the inflammatory state that keeps the condition active.

The intense itching that characterizes atopic dermatitis has its own pathophysiology. Research shows that people with atopic dermatitis have overreactive neural pathways, meaning their nervous system perceives itchiness more intensely than normal^[19]. This isn’t just about having sensitive skin—the nerves themselves respond differently to itch signals. This heightened sensitivity explains why the itching can be so severe and difficult to ignore.

Scratching introduces another layer of pathophysiology. When someone scratches itchy skin, they cause mechanical damage to the already weakened skin barrier. This damage allows more allergens and irritants to enter, triggers more immune activation, and produces more inflammation. The inflammation, in turn, causes more itching, creating the self-perpetuating itch-scratch cycle that makes atopic dermatitis so difficult to manage^[3].

The disrupted skin barrier in atopic dermatitis also makes the skin more vulnerable to infections. The bacteria Staphylococcus aureus (often called “staph”) commonly colonizes the skin of people with atopic dermatitis. This bacterium can cause secondary infections, particularly when scratching breaks the skin open. When infection occurs, it adds another source of inflammation and can cause weeping or crusting of the skin^[3]. Some people may also be more susceptible to viral skin infections, such as cold sores and warts^[4].

Environmental factors interact with these underlying genetic and immune abnormalities. Exposure to irritants like harsh soaps, hot water, or synthetic fabrics can damage the already compromised skin barrier. Temperature extremes—both heat and cold—can trigger flares. Dry climates or dry indoor air from heating systems can worsen the fundamental problem of skin moisture loss. Allergens from the environment, whether they’re in food, airborne particles, or substances that touch the skin, can activate the overactive immune system and trigger inflammatory responses.

Over time, chronic inflammation and repeated scratching lead to additional changes in the skin. The skin becomes thicker through a process called lichenification. Blood vessels in affected areas may become more visible. Areas of hyper-pigmentation (darker skin) or hypo-pigmentation (lighter skin) may develop, particularly noticeable in people with darker skin tones. These long-term changes reflect the cumulative effects of ongoing inflammation and damage.