Review consolidates the case for GLP-1 drugs in psoriasis

A review published in Frontiers in Immunology has gathered clinical evidence on GLP-1 receptor agonists in psoriasis and psoriatic arthritis, reporting that liraglutide and semaglutide were linked to lower Psoriasis Area and Severity Index (PASI) scores along with drops in several inflammatory markers, including interleukin-6, interleukin-17, interleukin-23, tumor necrosis factor alpha, and C-reactive protein ^[1]. The authors say some of these skin improvements appeared to happen independent of weight loss, which points to a possible direct anti-inflammatory effect rather than benefit driven only by pounds shed ^[1].

In one trial cited by the review, 25 people with psoriasis and type 2 diabetes who took liraglutide at 1.8 mg per day had bigger PASI improvements than those on conventional therapy, along with reduced skin levels of IL-17, IL-23, and TNF-alpha ^[1]. In another open-label trial of 31 people with psoriasis and type 2 diabetes, semaglutide at 1 mg per week was tied to lower blood IL-6 and CRP, along with improvements in PASI, BMI, and LDL cholesterol ^[1]. Evidence in psoriatic arthritis was far thinner: only one small study, of 10 adults with obesity and psoriatic arthritis on liraglutide 3 mg per day, showed improved disease activity scores along with lower BMI, waist size, blood sugar, lipids, and CRP ^[1].

A separate primer from the National Psoriasis Foundation's Medical Board, published in JAMA Dermatology, reviewed the same general topic and found a more mixed picture across three randomized trials ^[2]. In the only placebo-controlled trial, 20 people with obesity and plaque psoriasis took liraglutide 1.8 mg daily or placebo for eight weeks. The liraglutide group lost significantly more weight (4.7 kg versus 1.6 kg) but did not show a statistically significant PASI improvement over placebo ^[2]. A second trial of 31 people with psoriasis, obesity, and type 2 diabetes on semaglutide reported a 52% median PASI reduction along with improved quality-of-life scores, BMI, LDL, and CRP ^[2]. A third trial of 24 people with type 2 diabetes and psoriasis on acitretin found an 83% PASI reduction with liraglutide, compared with a smaller drop in the control group, plus lower IL-23 and IL-17 ^[2]. Across five smaller liraglutide studies, PASI reductions ranged from 23% to 85% ^[2]. Reported PASI reductions across prior research on these drugs range from roughly 40% to 80% among patients who also had obesity or type 2 diabetes ^[2].

The two reviews also flag possible harms. Dermatologic reactions to GLP-1 drugs are uncommon but can include bullous pemphigoid, eosinophilic panniculitis, morbilliform eruptions, and injection-site reactions affecting up to 30% of patients depending on the drug ^[2]. Some data tie GLP-1 use to a modest increase in risk of immune-mediated skin disease, with a hazard ratio of 1.17 ^[2], and one analysis found higher alopecia rates with tirzepatide compared with placebo ^[2].

Why it matters for patients

For people with psoriasis who also have obesity or type 2 diabetes, these findings suggest a GLP-1 drug taken for metabolic reasons might also ease skin symptoms, though the size of that effect varies a lot between studies, and one placebo-controlled trial found no significant skin benefit despite real weight loss ^[2]. Experts writing the National Psoriasis Foundation primer stress these drugs are approved for obesity and diabetes, not for psoriasis itself, and are not expected to match the effectiveness of standard psoriasis biologics used alone ^[2]. Cost is also a factor: GLP-1 therapy can run more than $7,000 a year, and insurance coverage may be limited when the prescription is not for an approved indication ^[2].

What happens next

Two larger trials, TOGETHER-PsA (NCT06588296) and TOGETHER AMPLIFY-PsA (NCT06864026), are testing tirzepatide alongside the biologic ixekizumab in people with psoriatic arthritis and overweight or obesity, and are expected to generate more solid data on joint and metabolic outcomes ^[1]. Researchers in both reviews call for larger, controlled trials, including ones that specifically test early psoriatic arthritis, before any firm treatment recommendations can be made ^[1][2].