Psoriasis and eczema are separate skin conditions, although they share some similar symptoms. Eczema is more commonly found in babies or young children and, unlike psoriasis, may go away over time. It is uncommon to have both eczema and psoriasis at the same time, but it is possible.
The most common form of psoriasis generally appears as red, scaly patches of dry skin with an overlying silver scale that may crack and bleed. Eczema patches can be brown-gray or red in appearance, may have pustules, and are typically less well-defined. Eczema tends to form where the skin folds, whereas psoriasis tends to be on the outer parts of the joints. Additionally, while both conditions cause itchy skin, the itching associated with eczema tends to be more extreme and almost universal for people with eczema.
Read more about psoriasis symptoms.
While both psoriasis and eczema on the scalp have commonalities such as itching and reddish skin, eczema does not usually appear as dry or with such thick scale. Additionally, eczema scales on the scalp have more of a whitish or yellowish hue versus the silvery one common in psoriasis. Read more about scalp psoriasis.
Psoriasis is typically found on elbows and knees, but a person with scalp psoriasis may find patches extending to the forehead, ears, and other areas close to the face. Eczema may also be found on the face and appears as scaly, dry patches without the silver scale. In both cases, there can be extreme itching and discomfort.
Eczema is more often found in folds near the joints, such as the inside or crook of the elbows. On the other hand, psoriasis is commonly found on the elbow itself.
Due to exposure to soaps, animals, and other allergens, eczema is commonly found on the palms of the hands. Psoriasis on the hands can be found on the back of the hands, palms, knuckles, and nails.
Psoriasis is often found on knees and legs. The type of psoriasis dictates the size of the spots, from smaller and widespread (guttate psoriasis) to larger plaques (plaque psoriasis). Eczema on the legs tends to form where the skin folds, such as behind the knees, whereas psoriasis is usually on the knee itself.
Although the skin symptoms of psoriasis and eczema can look and feel similar, the conditions are very different below the surface of the skin. Eczema is frequently related to allergies; many people with eczema also have food allergies, seasonal allergies and asthma. Psoriasis is a systemic disease, meaning that it affects the whole body. Psoriasis causes inflammation, fatigue, and other symptoms. About 30 percent of people with psoriasis develop psoriatic arthritis, which can cause progressive joint damage and lead to disability. Psoriatic disease can also cause uveitis (eye inflammation), which can result in loss of vision.
Eczema and psoriasis are caused by overactivation of different inflammatory pathways within the immune system. The cause of psoriasis, while not completely understood, is an autoimmune reaction wherein the immune system responds to a trigger and recruits many inflammatory cells into the skin.
The cause of eczema is not clear, but it is thought to be an extreme sensitivity — sometimes caused by an allergy — to certain triggering substances. It may also be due to a defect in the proteins that form the barrier of the skin. Common triggers for eczema flare-ups include animals, fabrics, soaps, metals, and certain medications. In other words, psoriasis is caused when your immune system attacks itself, and eczema is caused when your immune system overreacts to an outside substance.
Psoriasis is usually diagnosed when a dermatologist performs a visual exam and takes your medical and family history. In some cases, the doctor may do a biopsy (remove a small piece of skin for laboratory testing) to confirm the diagnosis. Read more details about psoriasis diagnosis.
Similarly, eczema is typically diagnosed by observing the skin and asking questions about medical and family history. A biopsy may also be done to help diagnose eczema. A patch test (attaching samples of different substances to the skin with tape) may be performed to see if the itchy rash is caused by an allergy to an external contact.
In some cases, genetic testing may be needed to differentiate between psoriasis and eczema.
Both psoriasis and eczema are treated by modulating the immune system. Topical corticosteroids are commonly used to treat both conditions since both lead to inflammation of the skin. The effects of topical medications are mostly limited to the skin.
Keeping skin moisturized can help control eczema. In severe cases of eczema, it may be necessary to take systemic oral medications such as Methotrexate or Mycophenolate mofetil. More recently, the biologic Dupixent (Dupilumab) has been developed. It’s an injection given twice each month to control the inflammation.
Since psoriasis is a chronic autoimmune disease that can cause systemic symptoms and progressive joint damage, it is important to calm the immune system throughout the body to control inflammation and reduce autoimmune attacks on the skin and joints. Systemic treatment options for psoriasis include immunomodulators, such as Methotrexate, and newer biologic drugs, such as Enbrel (Etanercept), Humira (Adalimumab), and Stelara (Ustekinumab), which are injected into the skin. There are more than 10 biologic medications that target the pathways associated with psoriasis. Phototherapy, or light therapy, may also be helpful in some cases of psoriasis. Read more about psoriasis treatments.