Psoriasis, Eczema, Dermatitis: How to tell these apart

A skin rash that results in itching and inflammation are is problem almost everyone has had to cope with at some point or other in their life.

The three common causes for this — psoriasis, eczema, and dermatitis — are tricky, which make it hard to diagnose.


Dermatitis is a very broad term that generally means a localised inflammation of the skin.

If symptoms flare up when skin comes in contact with a specific substance, you may have a case of contact dermatitis.

Contact dermatitis can be classified into two main types – irritant and allergic. A red, itchy rash is a common symptom in both types of contact dermatitis.

• Irritant contact dermatitis (ICD) is the most popular type of contact dermatitis. It develops when skin becomes inflamed from exposure to irritants such as chemicals, acids, soaps, and detergents.

Irritant contact dermatitis can flare up whether you have been exposed to an irritant substance before or not.

The most common symptoms you will develop when you have ICD is a rash on your hands along with burning, itching, and pain.

It is important to pinpoint which substances irritates your skin so you can avoid it altogether.

• Allergic contact dermatitis (ACD) can develop if you have a sensitivity or allergy towards a specific substance. Examples would be nickel or other metals, certain fragrances, and some medications.

With allergic contact dermatitis, apart from the main symptom of itching, a skin rash can appear on the area that touched the substance within 24 to 48 hours.

People with frequent allergic contact dermatitis flare-ups may be recommended allergy testing.


The exact cause of eczema is unclear, but most results from recent studies show it is associated to genetics and environmental factors.

The most common type of eczema is atopic dermatitis, an allergic condition that often develops in children. When children reach the age of two, the condition may disappear, or last till adulthood.

If you have eczema, your skin develops itchy patches that become red, swollen, and cracked from scratching. Rashes can be founded on the face, inside the elbows, behind the knees, and on the hands and feet.

It’s important to identify and avoid the substances that trigger an eczema breakout or make the condition worse.

Common irritants can be household cleansers, detergents, soaps, chlorine, wool, and also some drugs. Several environmental factors such as abrupt temperature changes or stress can also cause an outbreak of eczema.

However, diagnosing exactly what causes eczema is difficult, so do see a doctor or a dermatologist to confirm the actual type of skin rash you have.


Psoriasis is a long-term condition that many doctors view as an autoimmune disease. If you have psoriasis, you will usually experience thickened, red patches of skin and silvery-white scales.

Psoriatic patches can be itchy, sore, and even burn. They are often found on the outside of the elbows and knees. Psoriasis can also occur in the scalp and nails.

It is still unknown why certain people get psoriasis but many risk factors can trigger the condition, including stress, cold weather, skin damage, and certain medications.

Unlike atopic dermatitis, psoriasis doesn’t usually develop in those younger than 10. It more commonly appears in adults.

Since psoriasis can bear a close resemblance to other skin diseases, it is difficult for doctors to diagnose it. However, it can be identified by closely examining the skin, nails, and scalp.

In some occasions, your doctor or dermatologist may also perform a skin biopsy by removing a small skin sample and viewing it under a microscope to identify the type of psoriasis you have, and offer the best treatment.

It is important to know that no single test can specifically identify these skin conditions.

And since many get confused because the skin rashes look so similar, you should see your doctor to diagnose exactly what is happening to your skin.

This article first appeared in and was reviewed by Dr Duyen Le. The Hello Health Group does not provide medical advice, diagnosis or treatment.