In short.
Psoriatic arthritis is a chronic inflammatory disease that affects both joints and skin. Between 72% and 82% of people with this condition also have overweight — and at higher BMI, biologics such as ixekizumab often work less well.
In this trial, 271 adults received either ixekizumab alone (the standard treatment for joint inflammation), or the combination of ixekizumab plus Tirzepatide. After 36 weeks, the combination performed clearly better on almost every measure: fewer painful and swollen joints, more weight loss, better blood values, less fatigue and a higher quality of life.
What did they study?
The question was simple: does adding Tirzepatide to an existing joint treatment help bring the disease under better control?
Everyone who took part had:
- Active psoriatic arthritis (at least three painful and three swollen joints)
- A BMI of 30 or higher (obesity), or a BMI between 27 and 30 with a weight-related condition (such as high blood pressure, high cholesterol or sleep apnoea)
- A diagnosis of psoriatic arthritis for at least six months
Participants were randomly assigned to two groups. One group received ixekizumab alone according to the existing US prescribing rules. The other group received the same ixekizumab plus a weekly Tirzepatide injection, gradually increased to a maximum of 15 mg per week. Everyone also received personal nutrition and exercise guidance.
What did they find?
The headline result was strikingly clear. At week 36, the combination group had significantly better outcomes on almost every measurement:
31.7%
vs 0.8% — combination
Achieved both 50% improvement of joint symptoms and at least 10% weight loss (primary outcome).
84.5%
vs 4.5% — combination
Lost at least 10% of body weight.
33.5%
vs 20.4% — combination
Achieved 50% improvement in joint symptoms (ACR50).
~ 6.3 BMI
extra reduction over 36 weeks
On the combination versus ixekizumab alone.
In addition, blood pressure, cholesterol, glucose, HbA1c and triglycerides also improved in the combination group — consistent with what we already know about Tirzepatide. Striking finding: the first improvement in joint symptoms appeared at week 4, before any meaningful weight loss had occurred. That suggests Tirzepatide may have its own anti-inflammatory effect — not just via weight loss.
What about side effects?
The side effects more common in the combination group were largely the familiar Tirzepatide ones: nausea (30% vs 3%), diarrhoea (18% vs 4%), constipation (17% vs 3%) and vomiting (11% vs 1%). Mostly mild to moderate.
What didn't differ: serious side effects (in fact slightly fewer in the combination group — 3.6% versus 7.6%), hospitalisations and the percentage of people who had to stop. There were no deaths. The investigators conclude that the combination is safe within the known risk profile of both medications.
What does this mean for you?
Do you have psoriasis or psoriatic arthritis along with overweight or obesity? Then this is relevant news. The trial confirms something long suspected in clinical practice: weight isn't a separate 'lifestyle factor' in inflammatory diseases — it directly influences how well other medications work.
Three practical points:
- Lunaris does not prescribe ixekizumab itself — that's the domain of a rheumatologist or dermatologist. But we can think along about whether a Tirzepatide treatment makes sense in your situation alongside your existing therapy.
- Discuss it with your current specialist. If you're already on biologics for psoriasis or arthritis and you have overweight, adding Tirzepatide is a conversation worth having with your treating physician.
- Good coordination is essential. We always ask about your medication list during the intake. If you're already on a biologic, we involve your treating specialist when starting, so everything stays aligned.
Important caveats.
— This is one trial
TOGETHER-PsA is well-designed and large, but a single randomised trial is not a complete basis for long-term conclusions. Follow-up studies are already underway, and similar trials have been announced for psoriasis on the skin (without joint symptoms).
— Open-label design
The trial was 'open-label': doctors and patients knew which medication someone was taking. That is understandable (Tirzepatide causes weight loss — that's hard to hide), but joint and skin symptoms were assessed by blinded raters to limit bias.
— Sponsored by the manufacturer
The trial was funded by Eli Lilly, the manufacturer of both ixekizumab and Tirzepatide. That doesn't have to affect scientific quality — the data are publicly verifiable — but it's always good to know when reading the results.
— This trial says nothing about Lunaris
We're a primary-care clinic, not a rheumatology practice. We can't assess whether your psoriatic arthritis is well controlled — that's for your treating specialist. What we can do: think along about whether a Tirzepatide treatment for overweight is appropriate and safe in your situation, in coordination with your other care providers.
— Original source
Merola JF, Mease PJ, Kivitz A, et al. Ixekizumab With Tirzepatide Achieved Greater Disease Control Than Ixekizumab Alone in Adults With Psoriatic Arthritis and Overweight or Obesity: Results From a Randomized Clinical Trial. Arthritis & Rheumatology, 2026.
DOI: 10.1002/art.70134 · ClinicalTrials.gov: NCT06588296 · Open access (Creative Commons BY-NC).
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