Eczema happens when your immune system overreacts and attacks your skin. If you develop itchy skin or rashes unexpectedly, you might wonder, “Why did I suddenly get eczema?”

This answer is different for each person. However, learning how eczema works and what can trigger eczema can help you take better care of your skin.

Health experts aren’t exactly sure what causes eczema. Most believe it’s a combination of environmental risk factors (things around you) and genetics (things you inherit from your family) that leads to eczema symptoms in certain people but not others. You can’t catch eczema from someone else, but if a family member has it, you’re more likely to have it too. Living in certain places or using specific products can make the condition worse. Here’s what else scientists have found so far.

Risk Factors for Eczema

Science is good at finding links between possible risk factors and different conditions. However, these links don’t always prove that a risk factor causes the disease. Researchers have found several different risk factors for eczema, which they continue to study. However, they still haven’t found the exact cause of eczema.

Age

Age is a factor in the development of eczema. Younger children are at higher risk for developing eczema than older people. Many children with eczema will grow out of it, although it might flare up again later in life.

Family History

If a close family member has eczema, you’re more likely to develop eczema too. People with eczema are also more likely to have other immune-related conditions, like asthma and food allergies. The combination of eczema, asthma, and food allergies is known as the “atopic triad.” These related conditions — sometimes referred to as the “atopic march” when hay fever is included — tend to run in families.

Genes

One gene that has been found to play a key role in the development of eczema is the gene that controls the production of filaggrin. Filaggrin is a protein that helps form a protective barrier on the outer layer of skin. Studies have shown that people with a genetic variant that affects filaggrin are more likely to develop eczema because their skin doesn’t have as strong of a barrier. Without this protection, the skin can become more sensitive and can be irritated by things in the environment.

Immune System

Although eczema is not considered an autoimmune disease, the immune system does play a role in the condition. According to the National Eczema Association, in people with eczema, the immune system overreacts to things in the environment like allergens. This immune system response causes inflammation, which leads to eczema symptoms like dry skin and itchiness.

Having one or multiple autoimmune diseases may also increase a person’s risk of developing eczema. Studies have found that people with eczema are more likely to have autoimmune conditions like Crohn’s disease, lupus, and alopecia than people without eczema. This doesn’t mean autoimmune diseases cause eczema, but there could be connections between the conditions.

Allergies

Up to 30 percent of people with food allergies also have eczema. Hay fever, or allergic rhinitis, is a type of allergy that is related to eczema. When someone with both conditions has an allergy flare-up, their eczema symptoms may get worse.

Some people with eczema also have food sensitivities. Food sensitivities are different from allergies. While allergic reactions usually happen right after eating, bad reactions from a food sensitivity can take a few days to show up.

Chemicals and Detergents

Certain substances in your environment can trigger some types of eczema. For example, contact dermatitis is a type of eczema caused by irritants in the environment like harsh chemicals. For example, hairdressers may develop contact dermatitis from working with chemical hair dyes. Custodians may have eczema symptoms from using harsh cleaning products and detergents.

Climate

People who live in places with big changes in weather from season to season are more likely to have eczema flares. Eczema is more common in places with very cold and damp weather or hot and humid conditions.

Many people with eczema notice that their symptoms get worse at certain times of the year, like in summer or winter.

Pollution

Exposure to air pollution can increase the risk of eczema. Studies have found that pollutants, both outdoors and indoors (like tobacco smoke), are linked to a higher risk of atopic dermatitis, the most common type of eczema.

Can Eczema Be Prevented?

Since scientists aren’t sure why some people develop eczema, there’s no known way to prevent it. The genetic causes of eczema are beyond your control. However, you can take steps to avoid your eczema triggers and take good care of your skin.

Triggers are environmental factors that can cause an eczema flare. These triggers are different for each person with eczema. Some common triggers include allergens, harsh soaps, dry skin, weather changes, and stress.

Working with your dermatologist to figure out what triggers your eczema is the first step to getting it under control. Your dermatologist can suggest tips (like using moisturizing creams and lotions) to reduce skin inflammation and help protect your skin barrier. In addition to changing your skincare routine, eating an anti-inflammatory diet, managing stress, and trying treatments like phototherapy can help. If you have severe eczema or it affects your daily life, your dermatologist may suggest other eczema treatments.

Talk to People Who Understand

On MyEczemaTeam, the social network for people with eczema and their loved ones, more than 54,000 members come together to ask questions, give advice, and share their stories with others who understand life with eczema.

Have you noticed what triggers your eczema? Do you have any advice for others? Share your experiences in the comments below, or start a conversation by posting on your Activities page.