What’s the difference between psoriasis and eczema?

What is eczema?

Eczema is a general term that refers to a group of diseases characterized by an inflammation of the outer layer of the skin. The word “eczema” is widely used to refer to the atopic form of the condition (also known as atopic dermatitis), and is the term we use in this text. It is the most common type of eczema: 17% of Canadians will suffer from it at some point in their lives.

Eczema is usually hereditary. This means that children whose parents have eczema are more likely to suffer from this skin disease, and also to develop asthma or hay fever. In most cases, eczema first appears in early childhood.

With eczema, the barrier that protects the skin from external elements fails to play its protective role properly, allowing various irritants or allergens to penetrate the skin more easily. In addition, the immune systems of people with eczema overreact to these irritants and allergens, causing an inflammatory reaction.

What is psoriasis?

Psoriasis is not as common as eczema. It is estimated that 2% to 3% of Canadians suffer from it. Psoriasis is an auto-immune skin disease, which means the immune system mistakenly attacks the skin cells.

The term “psoriasis is often used to refer to the plaque form of the disease, which primarily affect adults. It is the most frequent kind (90% of cases). When psoriasis occurs in children, it is generally in the form of guttate psoriasis (teardrop-shaped spots).

What do eczema and psoriasis lesions look like?

The lesions caused by eczema and psoriasis have certain similarities, but also several distinctive characteristics that enable your health professional, for example, a family doctor or dermatologist, to make a diagnosis.

People with psoriasis can develop a complication known as psoriatic arthritis, which causes swelling and pain in the joints.

People with eczema tend to scratch a lot because of the itchiness, which can lead to skin infections and skin thickening (lichenification).

What triggers eczema or psoriasis symptoms?

Eczema and psoriasis lesions often appear in a cyclical fashion, i.e., they can flare up suddenly then disappear for a while (remission), then reappear when something triggers them.

Eczema flare-ups can be triggered by exposure to an allergen or irritating substance such as a chemical product, or to a rough-textured fabric, such as a wool sweater, that can irritate the skin. Environmental factors can also trigger symptoms, including extreme temperatures or very dry air. An eczema flare-up can also be triggered by a period of stress, an infection, or after eating certain foods.

With psoriasis, flare-ups are often triggered by sunburn or an injury (even a minor one) to the skin, for example nicking yourself when shaving, or an insect bite, a scratch, a bruise, or a blister. Some medications can also bring about psoriasis or cause a flare-up.

Certain other psoriasis triggers are similar to those that occur with eczema, including stress, an infection, or cold and dry weather. Psoriasis flare-ups are more common in people who suffer from obesity or who smoke.

How is eczema treated?

The treatment for eczema aims primarily to reduce inflammation and relieve symptoms. It should be adapted to the severity of the eczema, and may include the following:

• Daily use of an emollient cream to keep skin moisturized and prevent eczema flare-ups. It must be applied daily, during and between flare-ups.
• Application of a topical corticosteroid to reduce skin inflammation during eczema flare-ups. In very severe cases, injectable biologic drugs may be required.
• Antihistamines, especially at night, to relieve itching

How is psoriasis treated?

The treatment for psoriasis also focuses on reducing inflammation and managing symptoms. It may include the following:

• Topical creams and ointments: Corticosteroid, retinoid, or vitamin D-based products may be prescribed to reduce inflammation and thick plaques.
• Light therapy: Light therapy, or UVB treatment, consists of exposing the skin to controlled doses of ultraviolet rays, to reduce inflammation.
• Systemic drugs: In the most severe cases, oral or injectable medications such as immunosuppressive drugs may be required, to modulate the immune system response.
• Biologic treatments: Biologic treatments are an option for patients with severe, chronic psoriasis. They target immune system–specific proteins responsible for inflammation.

Identifying and avoiding triggers is also key to treating eczema and psoriasis. Reach out to your pharmacist for advice on which products to choose for your specific needs, for example a gentle soap or emollient cream.

If you have questions about how to treat eczema or psoriasis, ask your pharmacist. They are there for you!