Key Differences Between Eczema and Psoriasis You Need to Know

It can be easy to confuse eczema and psoriasis. Both are skin conditions. Both can cause itching and patches of red, dry skin. Both are chronic—meaning they never really go away. And both tend to be treated in similar ways. Look closely, though, and you will start to notice differences.

Causes of Psoriasis and Eczema

Both eczema (also known as atopic dermatitis) and psoriasis are thought to have the same cause: an immune system that kicks into overdrive and mistakenly attacks your own body. But the precise process is different for each condition.

"It's different wings of the immune system," said Emily Newsom, MD, assistant clinical professor of dermatology at UCLA David Geffen School of Medicine.

In psoriasis, overproduction of certain immune-system chemicals causes the outer layer of skin cells to go through the life cycle—forming then sloughing off—in just days rather than a month. The result is a layer of super-fast-forming cells building up on your skin. That's what causes the thick coating of red, silvery scales on your skin that are characteristic of plaque psoriasis—the most common type of psoriasis.

Eczema affects the ability of the skin to protect against outside irritants and allergens.

Symptoms

Eczema patches are not as thick as psoriasis plaques and appear mostly as dry skin that sometimes swells, cracks, and even oozes fluid—a telltale sign you're dealing with eczema, not psoriasis.

"Eczema is the extreme form of dry skin, while psoriasis is more like plaque on your skin," said Michele S. Green, MD, a dermatologist in New York City.

The outlines of the patches are also different. "Classically, the edges of eczema tend to be more ill-defined, whereas psoriasis is very sharply defined," Dr. Newsom said.

Symptoms of the two conditions also tend to show up on different parts of the body.

"Eczema is usually on the inside of the arms, backs of knees, and in the folds of your skin," Dr. Green said. That's why people with eczema can also get bacterial and yeast infections in those folds where sweat collects.

Psoriasis is more common on the scalp, lower back, knees, and elbows, but it can show up anywhere, including your face.

Eczema and psoriasis both itch (eczema usually more so), but some people with psoriasis say it also burns and strings.

Triggers for Psoriasis and Eczema

While both conditions are chronic, they can flare up from time to time in response to different triggers.

"Eczema is going to be triggered more by things you're coming into contact with, like fragrance, nickel, pollen, or preservatives," Dr. Newsom said. For some people, dust, mold, cigarette smoke, wool, polyester, and sometimes hormones can kick off eczema flares.

Psoriasis can be triggered by skin injuries, sunburns, scratches, and infections like strep throat, as well as alcohol and certain medications.

Stress and dry weather tend to be triggers for both conditions, Dr. Newsom said.

Diet may play a role in both conditions. Some people with psoriasis find some relief by following an anti-inflammatory diet. People with eczema may benefit from talking to a healthcare provider to help rule out food allergens that could trigger flares.

Another way to tell psoriasis and eczema apart is when they start. Although there are plenty of exceptions, eczema usually appears before the age of 5, while psoriasis usually comes on between the ages of 15–35.

Risks

Neither condition is just a cosmetic issue. They both are linked to larger health issues, but different ones. The inflammation associated with psoriasis raises the risk of diabetes, heart disease, and inflammatory bowel disease, for example.

"Psoriasis is an independent risk factor for heart disease, even controlling for body mass index and weight," Dr. Newsom said. "The inflammation in the body affects the heart."

Up to 30% of people with psoriasis will also develop psoriatic arthritis—a condition in which the immune system attacks the joints.

Some people with eczema go on to develop asthma and hay fever. A personal or family history of asthma or hay fever can in turn indicate a heightened risk for eczema.

Treatments

There are effective treatments for both psoriasis and eczema, and those treatments often overlap. For mild forms of either disease, many people get relief from self-care, including moisturizing and avoiding triggers.

More severe cases may require medication. Be sure to discuss your symptoms with a dermatologist to help determine the best course of treatment for you.