Eczema vs. Psoriasis

There are similarities and differences when comparing skin changes that occur with eczema vs. psoriasis. The affected skin can be red and dry with both. But eczema can be very itchy, though psoriasis usually is not. Psoriasis, on the other hand, tends to cause scaly plaques, while eczema causes bumps.

The most important differences to note are that these chronic skin conditions have different causes and may need different treatments.

It's important to see a healthcare provider if you have skin symptoms. They can confirm—either by physical exam or looking at skin cells under a microscope—that you have eczema, psoriasis, or something else entirely, like lupus or skin cancer. Then you can be sure you start the treatment you need.

This article details the similarities and differences between eczema and psoriasis, including the signs and symptoms they cause, why they occur, and how they can be managed.

Symptoms of Eczema vs. Psoriasis

Eczema and psoriasis both cause patches of inflamed, dry skin. Usually, you experience repeated episodes of these symptoms over time, which are called flares.

It can be hard for the untrained eye to tell eczema and psoriasis apart because they can look alike. In fact, eczema and psoriasis are commonly misdiagnosed as each other in babies and kids.

However, a skin specialist (dermatologist) can easily see the differences between the conditions. In particular, they will look for differences in what skin is affected, how it looks, and the extent of any itching.

Location

Psoriasis and eczema both cause rashes on your skin, but they show up on different parts of your body.

The most common places to see eczema and psoriasis are:

• Eczema (atopic dermatitis) most often appears in the crook of the elbows and the backs of the knees (flexural surfaces).
• Psoriasis is more often seen on the outside of the forearms and elbows, or the fronts of the knees and shins (extensor surfaces).

Psoriasis can also show up on your scalp, face, lips, ears, neck, navel, arms, legs, feet, hands, ankles, and lower back. While eczema can also occur in these areas, it’s usually not as severe as it is with psoriasis.

Eczema and Psoriasis of the Nails

Eczema and psoriasis can cause ridges, discoloration, and thickening of the finger and toenails. However, only psoriasis causes little holes in your nails (pitting of the nail plate).

Appearance

Eczema and psoriasis can both cause dry, red patches of thickened skin, but there are some specific characteristics that can help separate one from the other. For example, scaling is a major sign of psoriasis. You may have scaling if you have eczema, but it doesn't always happen.

In addition, eczema can cause:

• Rash
• Swelling
• Bumps (papules)
• Fluid-filled pockets (vesicles)
• Generalized areas of darkened, leathery, thickened skin (lichenification)
• Oozing and crusting (in severe eczema)

While psoriasis shows up as:

• Well-defined patches of reddened skin that are covered with fine, silvery-white scales called plaques
• Plaques that bleed easily when scratched and leave behind a pinpoint pattern of blood spots (Auspitz sign)
  

Itching

Itching (pruritus) can be part of having psoriasis, but you're more likely to have itchy skin if you have eczema. The itching from eczema can be severe.

The causes of itching are a little different for psoriasis and eczema:

• If you have psoriasis, the itching is thought to happen because the inflammation in your skin bothers nerve receptors called nociceptors.
• Nociceptors also get irritated in eczema, but the irritation is made worse by an antibody called immunoglobulin E (IgE) that is linked to allergies. People with eczema have IgE antibodies, but people with psoriasis do not.

Causes

Both eczema and psoriasis are inflammatory skin conditions. That means that inflammation in the skin leads to symptoms. However, the cause of the inflammation is different for each condition.

Eczema and an Overactive Immune System

Researchers think eczema is caused by an overactive immune system. The immune system malfunctions and the body makes too many white blood cells called T-cells. The cells trigger an inflammatory response to defend the body against infection.

With eczema, the inflammation causes cells in the lymph nodes to pump IgE into the bloodstream. The IgE causes the cells of the outer layer of your skin (epidermal cells) to swell and skin changes, like bumps and thickening, to occur.

Psoriasis: An Autoimmune Disease

Psoriasis is an autoimmune disease, meaning the body causes inflammation on purpose because it thinks there is a threat.

The immune system suddenly sees normal skin cells as harmful and it attacks them by sending out T-cells.

The T-cells target new (immature) skin cells called keratinocytes. The inflammation makes the cells divide faster. Usually, it takes 28 to 30 days for new cells to turn over. In psoriasis, they do so every three to five days.

Since the cells are being made faster than the body can shed them, they get pushed to the surface of the skin and form lesions.

What Triggers Eczema or Psoriasis?

Most health conditions have more than one thing that contributes to them, and that is true of eczema and psoriasis. For example, genetics and environmental triggers seem to play a role in both conditions.

Scientists are still trying to understand the role of genetics in psoriasis and eczema. They know more about how certain things in a person’s environment trigger these conditions or make their symptoms worse.

Eczema Triggers

Since eczema is related to IgE antibodies, common allergens can trigger flares. These allergens include:

• Dust mites
• Pet dander
• Pollen
• Mold
• Dairy products
• Eggs
• Nuts and seeds
• Soy products
• Wheat

Psoriasis Triggers

The things in your environment that could trigger psoriasis are not as specific as the things that seem to trigger eczema. However, many things that make other autoimmune diseases flare up also trigger psoriasis, including:

• Infections
• Alcohol
• Smoking
• Skin trauma (Koebner phenomenon)
• Certain medications (such as beta-blockers, lithium, and antimalarials)

Diagnosis

There are no blood or imaging tests that can diagnose eczema or psoriasis. Your provider will look at your skin and ask you about your general health to figure out what is causing your symptoms. They might ask you about any medical conditions that run in your family.

Your provider may want to take a tiny sample of your skin to look at under a microscope (biopsy).

Here’s what they might see:

• In eczema, the inflammation causes swelling of the outer layer of your skin (spongiosis). Under a microscope, there will be large spaces between the skin cells and visible papules and vesicles.
• In psoriasis, the inflammation causes your skin to make too many skin cells (hyperproduction of keratinocytes). Under a microscope, the skin cells will look thick and compressed (acanthotic).

Treating Eczema vs. Treating Psoriasis

The goal of treatment is the same for eczema and psoriasis: to reduce inflammation and make your symptoms better. Some treatments work for both conditions, including:

• Emollient-rich moisturizers
• Topical corticosteroids
• Oral antihistamines (to relieve itching)
• Staying away from triggers

The treatment that will work best for one condition is not always the one that will work best for the other. Here are some key ways that treating eczema and psoriasis can be different:

• Immunosuppressant drugs: Methotrexate and cyclosporine suppress the immune system. They can treat moderate to severe psoriasis. For people with eczema, the treatments are only used in severe cases.
• Phototherapy: Ultraviolet (UV) light therapy (phototherapy) is the main treatment for moderate to severe psoriasis. There is not much research on using it to treat eczema.
• Topical calcineurin inhibitors: Calcineurin inhibitors are medications that keep T-cells from being activated. This type of medication is approved by the Food and Drug Administration (FDA) to treat eczema. The drugs can also be used for psoriasis, but off-label (without official FDA approval). Protopic (tacrolimus) and Elidel (pimecrolimus) are two examples of this type of medication.
• TNF inhibitors: Tumor necrosis factor (TNF) inhibitors block a key inflammatory compound linked to psoriasis. Medications like Humira (adalimumab) and Enbrel (etanercept) are examples of TNF inhibitors. These medications are not approved to treat eczema and can actually make it worse because the inflammatory compounds in eczema are not the same as those in psoriasis.
• Janus kinase (JAK) inhibitors: JAK inhibitors are medications that selectively block immune signals that cause inflammation and itching. Cibinqo (abrocitinib) and Rinvoq (upadacitinib) are examples of this type of drug. Both medications are approved by the FDA to treat moderate to severe eczema.
  

Summary

Eczema and psoriasis are chronic skin conditions. Symptoms can be similar, but the causes and treatments for the conditions are different. If you have skin symptoms like a rash, itching, bumps, or lesions, see your primary healthcare provider or a dermatologist.

Some treatments can be used for either condition, but depending on how severe your symptoms are, you might need a treatment that is specifically made for the condition you have.