GLP-1s and Psoriasis: What the Research Shows

GLP-1-class drugs may help psoriasis in people who also have obesity, and as of 2026 there's randomized trial evidence to back that up. In a phase 3b trial published in JAMA Dermatology, adding tirzepatide (the drug in Zepbound and Mounjaro) to the biologic ixekizumab improved skin clearance and produced far more weight loss than ixekizumab alone. Before that trial, the evidence was mostly small, uncontrolled studies.

That's genuine progress. But the trial tested tirzepatide alongside a biologic, not instead of one, and it doesn't settle whether the benefit comes from weight loss, from an anti-inflammatory effect, or both. No GLP-1 medication is approved to treat psoriasis.

Why researchers expected a link

Psoriasis is an immune-driven inflammatory disease, and it tends to travel with metabolic conditions. A 2026 review from the National Psoriasis Foundation Medical Board in JAMA Dermatology lists cardiovascular, metabolic, liver, kidney, and other comorbidities that are associated with psoriasis. Several of those are conditions GLP-1 drugs are already approved to treat or reduce the risk of, including type 2 diabetes, obesity, cardiovascular events, chronic kidney disease, sleep apnea, and fatty liver disease with inflammation (MASH).

Researchers also had biological reasons to look. The NPF review summarizes findings that semaglutide and liraglutide were associated with lower inflammatory markers such as CRP and IL-6, along with lower lipids and visceral fat. In small lab-linked studies, psoriasis improvement tracked with reduced fat under the skin and fewer of a specific immune cell type in the skin. Those are mechanism signals, not proof of a treatment effect.

The 2026 randomized trial: TOGETHER-PsO

The most important study so far is TOGETHER-PsO, published in JAMA Dermatology in 2026. Here's how it was set up:

• Who: 274 adults with moderate to severe plaque psoriasis who had obesity, or overweight with at least one weight-related condition. Average BMI was 39 and average PASI score (a measure of psoriasis severity) was about 20.
• What: Participants were randomly assigned to ixekizumab (an IL-17 biologic, sold as Taltz) plus tirzepatide, or ixekizumab alone. Both groups were also advised on diet and exercise.
• Design: Open-label, meaning participants and clinicians knew which treatment each person got. 72 U.S. sites. Primary results at 36 weeks.

Here are the main results:

How to read these numbers

The headline primary endpoint combined skin clearance with weight loss. That design makes sense for a trial of a weight-loss drug, but it means the big gap (27.1% vs 5.8%) is driven heavily by the weight-loss half. Very few people lose 10% of their body weight on ixekizumab alone.

The cleaner question for most patients is whether skin got better. On that, the combination group reached completely clear skin more often, 40.6% vs 29.0%. That difference was statistically significant, but the confidence interval was wide, running from a 0.3 to a 22.9 percentage-point advantage. So the combination likely helps skin clearance, but the size of the benefit is uncertain.

Other limits worth knowing:

• Open-label. Without a placebo injection, knowing you're on the extra drug can influence behavior and reporting. PASI is assessed by clinicians, which helps, but blinding would have been stronger.
• Sponsor. The study was funded by Eli Lilly, which makes both drugs, and several authors are Lilly employees. That's common for phase 3 trials and doesn't invalidate the results, but independent replication matters.
• One biologic. The trial tested only ixekizumab. Whether the same add-on effect holds with other biologics, methotrexate, or topical treatment alone isn't known.
• Weight vs drug effect. The design can't separate how much of the skin benefit came from weight loss versus any direct anti-inflammatory action.

On safety, the authors reported no new concerns. GI side effects were more common with the combination, as expected with tirzepatide. Three participants in the combination arm stopped because of adverse events, including two skin infections and one case of noncardiac chest pain.

What earlier studies showed

Before TOGETHER-PsO, the evidence came mostly from semaglutide and liraglutide. The NPF review summarized those studies as reporting relative PASI reductions of about 40% to 80%, along with better quality-of-life scores. It was also blunt about their limits: most enrolled 7 to 48 patients, ran six months or less, and had no control group.

Uncontrolled studies are especially hard to interpret in psoriasis because the disease naturally waxes and wanes, and people often enroll when it's at its worst. Some improvement would be expected over time even without a new drug. A 2024 narrative review in Psoriasis: Targets and Therapy noted that case reports and cohort studies mostly showed improvement, but the two small randomized trials available at that point had conflicting results.

Real-world data are also emerging. A 2026 prospective study of 64 patients already on stable ixekizumab, published in Dermatology and Therapy, reported that average PASI fell from 4.2 to about 1.0 over 24 weeks after adding low-dose tirzepatide, with about 10% average weight loss. It had no comparison group.

What professional groups say

The National Psoriasis Foundation Medical Board's 2026 primer is the clearest professional statement so far. Its conclusion is measured: current evidence supports considering GLP-1 drugs as an add-on for selected psoriasis patients who also have metabolic comorbidities, and definitive conclusions require larger randomized trials. The review also noted that GLP-1 drugs can be used alongside methotrexate, cyclosporine, and biologics, with mostly temporary GI side effects and rare pancreatitis and gallbladder events.

That framing matters. It doesn't say GLP-1s treat psoriasis. It says that for someone who already has a reason to take one, such as obesity, type 2 diabetes, or cardiovascular risk, the skin may be an added reason, and the drug can generally fit alongside existing psoriasis treatment.

Evidence at a glance

Practical points if you have psoriasis

Keep your psoriasis treatment

The trial evidence is for a GLP-1 added to a biologic. There's no basis for stopping or reducing a biologic, methotrexate, or other treatment because you've started a GLP-1. If your skin improves a lot, that's a conversation to have with your dermatologist, who can decide whether any change makes sense.

Tell both prescribers

Your dermatologist should know you're on a GLP-1, and your GLP-1 prescriber should know what you take for psoriasis. GLP-1s slow stomach emptying, and their labels advise monitoring when they're combined with oral drugs that depend on reaching certain blood levels. Oral psoriasis treatments such as methotrexate, cyclosporine, or apremilast are worth flagging so both clinicians can decide whether any monitoring is needed. Our interaction guide covers this in more detail.

Watch for infections and skin changes

Biologics affect the immune system. The TOGETHER-PsO trial didn't flag new safety concerns, but two of the discontinuations in the combination arm were skin infections. Report any red, hot, rapidly spreading, or very painful skin area promptly.

Questions to bring to your dermatologist

1. Is my psoriasis likely tied to weight or metabolic health? Ask whether your clinician thinks weight loss could help in your case.
2. Do I have another reason to consider a GLP-1? Obesity, type 2 diabetes, fatty liver, sleep apnea, or cardiovascular risk are the settings where professional guidance supports considering it.
3. How would it fit with my current treatment? Ask whether anything about your biologic or oral medication needs monitoring.
4. How will we measure whether it helps? Agreeing on a baseline PASI or photos before starting makes later changes easier to judge.
5. What would make us change course? Clarify what side effects or results would prompt a change, and who manages each medication.

For other areas where research on these drugs is moving, see emerging GLP-1 benefits in 2026.