Explainer | How to tell the difference between eczema and psoriasis, so you can get the right treatment
- Both conditions cause itchy rashes; eczema is often associated with allergic conditions, while psoriasis is more an immune system problem
- Eczema is common in childhood, while psoriasis – which can lead to other conditions, including diabetes and heart disease – affects both adults and children
Eczema and psoriasis are common inflammatory skin conditions. Both can cause itchy rashes and appear on the same parts of the body – to an untrained eye they are easy to mix up.
Treatments for mild and moderate cases of these conditions are similar, but severe cases may require more specific medications.
We explain the causes, symptoms, and treatment of eczema and psoriasis and what makes them different.
What is eczema?
Eczema, also called atopic dermatitis, is a common skin condition affecting up to 10 per cent of people.
Its telltale symptoms include a dry, itchy rash that can range from minor patches to severe flare-ups that cause intense itching and sometimes pain due to scratching.
“Eczema is most commonly seen in kids – 95 per cent of cases by five years of age – and much less in adults,” says Anar Mikailov, a dermatologist and the founder of KP Away.
Eczema is associated with allergic conditions like asthma, hay fever, and food allergies. More than half of children under age 13 with eczema will go on to develop these other conditions.
You are more likely to have eczema if members of your family also have asthma or environmental allergies. Black children tend to develop it more frequently (19 per cent) than white (16 per cent) or Asian children (8 per cent).
Causes of eczema
Immune system: When you have an impaired skin barrier your skin is more vulnerable to environmental irritants. Your immune system sees these irritants as dangerous and responds with inflammation, which creates itching and a rash.
Environment: Flare-ups of eczema symptoms can be caused by many different environmental irritants. Some of the more common triggers include:
Household cleaning and bath products
Cosmetic products with artificial scents
Dust and pollen
Climatic factors – change in seasons or extreme weather
Other factors that may increase the risk of developing eczema include where you live. It is more common if you live:
In a city
In a high-income country like the US
Around weather that is cold and damp
High levels of stress affect the immune system and skin and increase the inflammatory response that causes eczema.
Symptoms of eczema
The main symptom of eczema is itching, which can be very intense and is often worse at night.
“The itch starts before the rash, and it shows up in symmetric areas on your body. In kids, symmetric rash with itching occurs near the elbows, knees, around the eyes, forehead, and nose,” says Mikailov.
Eczema can also cause:
A discoloured rash – on light coloured skin it will be red, on darker skin it can look darker brown, purple, or grey
Thickened and scaly skin due to frequent scratching
Oozing or crusting areas of skin
Treatment of eczema
Hsu says that although often effective, these medications are not cures – eczema is a chronic condition and occasional flare-ups are to be expected if not properly managed by a dermatologist.
What is psoriasis?
Psoriasis causes a dry, itchy rash characterised by scaly patches of skin. It is fairly common, affecting about three per cent of adults in the US – or almost eight million people.
Psoriasis is a chronic, incurable condition that tends to have intermittent flare-ups with worsening symptoms.
“Unlike eczema, psoriasis can be seen in childhood as often as adulthood, and affects men and women equally,” says Mikailov.
Causes of psoriasis
Psoriasis is an autoimmune condition – the body’s defence system sees normal, healthy cells as dangerous and releases antibodies to attack them – so the cause of psoriasis is a mechanism similar to other autoimmune diseases like rheumatoid arthritis, lupus, and Hashimoto’s thyroiditis.
In the case of psoriasis, T-cells from the immune system attack healthy skin cells. This causes the body to accelerate the creation of new skin cells – these new cells build up on the surface of the skin, creating psoriasis’ distinctive scaly appearance.
Psoriasis tends to run in families, and has some common triggers, both for its first incidence as well as flare-ups once it’s established. Common triggers include:
Infections – of the skin and especially strep throat
Injury to the skin, like scrapes or cuts
Weather, especially when it’s cold and dry
Heavy alcohol use
Psoriasis can affect people in different ways. Minor cases might be just a few spots of flaky scaling skin, while some cases can affect large portions of the body. The most common places psoriasis appears are the scalp and face, elbows, knees, feet, and the lower back.
Symptoms of psoriasis
In addition to a scaly rash, symptoms of psoriasis include:
Dry and cracked skin that can itch and bleed when scratched
Pitted or cracked nails
Burning or sore skin
About one in four people with psoriasis will develop a condition called psoriatic arthritis, which usually occurs years after psoriasis on the skin begins. Psoriatic arthritis shares similarities with rheumatoid arthritis – both cause joint pain, swelling, and, in some cases, deformity of joints.
People with psoriasis are more likely to develop other conditions such as:
Type 2 diabetes
High blood pressure
Inflammatory bowel disease or other autoimmune conditions
Treatment of psoriasis
“Treatment for psoriasis involves corticosteroid creams, vitamin D cream, phototherapy, and sometimes injected or ingested medicine. Fortunately, due to the new medicines, psoriasis can be essentially cured,” says Mikailov.
You can expect to see improvement in one to two months with injection medicine. Creams and phototherapy can require two to three months before improvement, says Mikailov.
Eczema vs psoriasis
“These two common conditions can look similar to the untrained eye – they both appear to be red scaly rashes initially, and in mild cases, the treatments can be very similar,” says Hsu.
Both conditions are caused by immune system dysfunction. In eczema the immune system is overactive, whereas in psoriasis the immune system attacks healthy cells – so in severe cases medications for each will differ, says Hsu.
Psoriasis, being an autoimmune condition, has more complications than eczema. “While some cases of eczema can be severe, causing much discomfort and itch, psoriasis tends to have more serious and wide-ranging multi-systemic consequences, including arthritis, heart disease, and diabetes,” says Hsu.
The main differentiation between eczema and psoriasis is itching: eczema is always itchy, sometimes intensely so, but itching with psoriasis is more mild and tends to be accompanied by a burning or stinging sensation.
Eczema and psoriasis are both common skin conditions that can be hard to tell apart. However, they can usually be treated similarly with topical medications.
For moderate and severe cases, a trained dermatologist will be able to differentiate the two and give you the best recommendations for treatment.