Eczema happens when your skin barrier breaks down and lets irritants in
Eczema is not caused by a single thing. Instead, it develops when your skin's outer layer — which normally keeps moisture in and irritants out — stops working properly. This breakdown lets water escape and allows bacteria, allergens, and chemicals to penetrate deeper into your skin, causing inflammation, itching, and the red, cracked patches you see.
The reason your skin barrier fails in the first place depends on a mix of factors: your genes, your environment, and what touches your skin. Some people are born with genes that make their skin less able to hold onto moisture or fight inflammation. Others develop eczema because of repeated exposure to something that irritates them — harsh soaps, extreme weather, stress, or an allergen their body reacts to.
Understanding what triggers your eczema matters because triggers vary from person to person. What causes a flare for one person may not affect another at all. The goal is to identify your own triggers so you can avoid them or manage them when you cannot.
Key Takeaways
- Eczema develops when your skin barrier weakens, allowing irritants and moisture loss that cause inflammation and itching.
- Genetics play a major role — if your parents have eczema, allergies, or asthma, you are more likely to develop it.
- Common triggers include soaps and detergents, dry air, stress, sweat, certain fabrics, and temperature changes.
- Identifying your personal triggers through observation and testing is the most practical way to reduce flares.
- Eczema is not contagious and does not spread from person to person, though the condition itself is lifelong.
Genetic factors that make your skin more vulnerable
If eczema runs in your family, your risk is significantly higher. Research shows that people with a parent or sibling who has eczema are much more likely to develop it themselves. This is not because eczema is inherited directly, but because you inherit the genes that control how your skin barrier functions and how your immune system responds to irritation.
Genetics also influence whether you develop other conditions alongside eczema. People with eczema often have a family history of asthma, hay fever, or food allergies. These conditions share similar immune system patterns, which is why dermatologists sometimes refer to the combination as the "atopic triad." Your genes determine whether your immune system tends to overreact to harmless substances.
Even if you have the genetic predisposition, eczema may not appear unless environmental triggers activate it. Some people carry the genes but never develop symptoms. Others develop eczema in childhood and outgrow it, while some experience their first flare as an adult.
Irritants that damage your skin barrier directly
Soaps and detergents are among the most common culprits. Regular bar soaps, body washes, and laundry detergents strip away the natural oils that protect your skin. Even products labeled "gentle" or "hypoallergenic" can trigger eczema in sensitive people. Fragrance — whether synthetic or natural — is a frequent irritant, as are preservatives and dyes.
Other everyday irritants include hot water, which opens your pores and lets moisture escape; chlorine in swimming pools; and rough fabrics like wool or synthetic materials that physically irritate the skin. Sweat, especially when trapped under clothing, can also trigger flares. Some people react to specific chemicals in cosmetics, sunscreen, or moisturizers — even products meant to help.
The key is that irritants work differently than allergens. An irritant damages your skin barrier through direct contact, and almost anyone exposed long enough will react. An allergen, by contrast, only triggers a reaction in people whose immune system recognizes it as a threat.
Allergens your immune system overreacts to
An allergen is something your immune system mistakenly identifies as dangerous and attacks, even though it is harmless. Common allergens that trigger eczema include dust mites, pet dander, pollen, mold, and certain foods. When your skin comes into contact with an allergen — or when you eat one — your immune system releases chemicals that cause inflammation, itching, and the visible signs of a flare.
Food allergies can trigger eczema in some people, particularly in children. Common culprits are milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat. If you suspect a food is triggering your eczema, keep a diary of what you eat and when flares occur. A dermatologist or allergist can perform tests to confirm whether a specific food is the problem.
Allergens differ from irritants in an important way: your body has to be sensitized to them first. This means you may not react the first time you encounter an allergen, but after repeated exposure, your immune system learns to recognize it and overreact. This is why some people develop eczema triggered by something they have been exposed to for years without problems.
Environmental conditions that dry and stress your skin
Dry air is one of the most powerful eczema triggers. Winter heating, air conditioning, and low humidity all pull moisture from your skin faster than it can be replaced. This is why many people experience worse eczema in winter or in dry climates. Even a few hours in a heated room can trigger a flare if your skin barrier is already compromised.
Temperature extremes — both hot and cold — can trigger eczema. Cold weather dries skin out. Hot weather causes sweating, which irritates skin when sweat sits on the surface. Sudden temperature changes, like moving from a cold room to a hot one, can also provoke a reaction.
Humidity matters too, but not always in the way people expect. While very low humidity is clearly problematic, very high humidity can trap sweat and bacteria on your skin, creating an environment where eczema flares. The ideal range varies by person, but most people with eczema do better in moderate humidity.
Stress and emotional triggers that worsen inflammation
Stress does not cause eczema, but it can trigger or worsen flares in people who already have it. When you are stressed, your body releases hormones like cortisol that increase inflammation throughout your body, including in your skin. Additionally, stress can weaken your immune system's ability to maintain your skin barrier.
The relationship between stress and eczema works both ways. A stressful event can trigger a flare, and then the itching and discomfort of the flare creates more stress, which worsens the eczema further. Breaking this cycle often requires both managing the skin condition itself and finding ways to reduce stress — through exercise, sleep, relaxation techniques, or talking to a mental health professional.
Emotional triggers are highly individual. Some people notice flares during exam periods, work deadlines, or relationship conflicts. Others flare during major life changes or grief. Tracking when your eczema worsens in relation to stressful events can help you recognize your own pattern.
Infections and microbes that inflame damaged skin
Eczema itself is not an infection, but infected eczema is common. When your skin barrier is broken and inflamed, bacteria — especially Staphylococcus aureus — can colonize the area and make the eczema much worse. Signs of infection include increased redness, warmth, pus, crusting, or swollen lymph nodes.
Viral infections can also trigger eczema flares. Some people experience worse eczema when they have a cold, flu, or other viral illness. This happens because the infection activates your immune system, which then overreacts in your skin as well.
If you suspect your eczema is infected, see a dermatologist. Infected eczema usually requires treatment with antibiotics or antiviral medication in addition to your regular eczema care. Preventing infection by keeping your skin moisturized and avoiding scratching is easier than treating it after it develops.
Frequently Asked Questions
Can eczema be caused by poor hygiene?
No. Eczema is caused by genetics and environmental triggers, not by being unclean. In fact, frequent washing with regular soap can worsen eczema by stripping away protective oils. People with eczema often need to wash less frequently and use gentler cleansers than people without the condition.
Does eczema get worse as you get older?
Eczema patterns change over a lifetime. Many children outgrow it by adulthood, but some experience their first flare as an adult. Others have eczema throughout their life but find their triggers change with age, stress level, or environment. There is no single trajectory — it depends on your genetics and life circumstances.
Can you develop eczema from touching someone who has it?
No. Eczema is not contagious. You cannot catch it from another person. However, if you have the genetic predisposition and are exposed to the same environmental triggers as someone with eczema, you might develop it independently.
Is eczema caused by an allergy?
Eczema and allergies are related but different. Some people with eczema also have allergies, and allergens can trigger flares. But eczema can develop and persist without any allergies being involved. A dermatologist or allergist can test whether specific allergens are triggering your eczema.
Why does my eczema flare at certain times of year?
Seasonal flares usually happen because of humidity, temperature, or allergen changes. Winter flares are common due to dry indoor heating and cold air. Spring and fall flares may be triggered by pollen or mold. Tracking when your flares occur can help you identify your seasonal pattern and prepare in advance.