< At-a-Glance Summaries

Why do some people with psoriasis develop eczema after receiving treatment?

Date of Publication:

October 2025

Background

Psoriasis and eczema are common inflammatory skin conditions with different symptoms and appearance, and it is rare for them to occur together. Both of these conditions are linked to a dysregulation of the immune system, but the specific changes to immune cells and molecules are different, i.e. psoriasis and eczema have distinct immune features. A type of injectable medicines, called biologics, are very effective for treating psoriasis, but some individuals develop eczema after starting treatment, and the reasons for this are unknown. This research looked at why some people with psoriasis, who are treated with biologic drugs, develop a different skin condition called paradoxical eczema.

To investigate this, researchers collected blood samples from people with psoriasis being treated with biologics, including some who developed paradoxical eczema and some who did not. They used techniques that look at how individual immune cells are communicating, to find out specifically which immune cell types are involved and what chemical signals they are actively sending out. The scientists measured levels of RNA and protein in each cell, then compared these measurements between samples taken from those who developed paradoxical eczema, and samples from those who did not.

Key findings

This research found that certain immune system chemical signalling molecules, such as tumour necrosis factor (TNF) and types of interferons (IFN-γ and IFN-α), were more active in people who developed paradoxical eczema than in those who did not.
The researchers identified that genetic differences linked to these immune features were also associated with developing eczema, suggesting that someone’s genetic predisposition could play a role in whether they experience this side effect or not.
The overall pattern of immune cell activity in these cases was different to the usual immune patterns seen in atopic eczema cases, but the immune changes in atopic eczema are highly variable over time and between individuals.

What this means

This study suggests that in people with psoriasis taking biologic drugs, development of paradoxical eczema is linked to specific immune patterns, and individual genetics might play a role in determining who develops this new skin condition. Understanding these patterns may help to guide treatment once eczema develops, or predict who is at risk of this reaction to inform early treatment decisions.

The full paper is available online at: https://doi.org/10.1016/j.jid.2025.02.153

Written by Dr Ali Al-Janabi and Jade Pizzato