Skyrizi vs Stelara for Ulcerative Colitis: A Comparison

Skyrizi and Stelara are two interleukin-pathway biologics increasingly used for moderate-to-severe ulcerative colitis. Skyrizi gained UC approval in June 2024, joining Stelara in the IL-23 targeting category. The two drugs take meaningfully different approaches. Skyrizi blocks only IL-23. Stelara blocks both IL-12 and IL-23. For Crohn's, the SEQUENCE head-to-head trial showed Skyrizi's p19 selectivity outperformed Stelara on endoscopic endpoints, and UC patients often want to know whether similar logic applies to their disease. This guide walks through the current evidence and practical considerations for the skyrizi vs stelara ulcerative colitis decision.

IL-23 p19 vs IL-12/23 p40

Skyrizi (risankizumab) binds the p19 subunit of interleukin-23, selectively blocking IL-23. Stelara (ustekinumab) binds the p40 subunit shared by IL-12 and IL-23, blocking both cytokines. IL-23 is the dominant driver of the Th17 pathway that fuels UC inflammation, while IL-12 plays a broader role in normal immune function. The scientific rationale for p19 selectivity is that blocking only IL-23 delivers the needed anti-inflammatory effect while preserving IL-12-mediated immune function that may matter for infection surveillance. In practice, the IL-23 p19 vs IL-12/23 distinction has translated into meaningful efficacy gaps in Crohn's head-to-head data, and UC patients often ask whether the same pattern holds for their disease.

UC Efficacy Data

Skyrizi's UC approval rests on the INSPIRE induction trial and the COMMAND maintenance trial. INSPIRE randomized biologic-experienced and biologic-naive UC patients to IV induction and showed clinical remission rates of 20.3% on Skyrizi versus 6.2% on placebo at week 12. COMMAND showed sustained remission and endoscopic improvement through week 52, with Skyrizi patients maintaining steroid-free remission at meaningfully higher rates than placebo. Stelara's UNIFI trial established UC efficacy across biologic-naive and biologic-experienced patients. No head-to-head trial has directly compared the two drugs in UC, so comparisons rely on cross-trial network meta-analysis. Indirect comparisons generally show both drugs deliver similar clinical remission rates in UC, with some evidence favoring p19 selectivity on endoscopic endpoints.

Onset of Action

Both drugs produce clinically meaningful response by week 12, which is standard for IL-23 pathway biologics. Skyrizi's INSPIRE trial showed significant improvements in clinical response as early as week 4 in a subset of patients. Stelara's UNIFI showed similar early response patterns after IV induction. Neither drug is as fast in UC as an anti-TNF like Humira or Remicade. For UC patients with severe, active symptoms who need rapid symptom control, an anti-TNF or a JAK inhibitor may fit better than either IL-23-targeted biologic. For patients in a less acute state or those who have already failed an anti-TNF, Skyrizi and Stelara both offer reasonable onset timelines.

Safety and Tolerability

Both drugs have favorable safety profiles relative to anti-TNFs. Long-term Stelara data shows lower rates of serious infection and hospitalization compared with infliximab in IBD cohorts. Skyrizi's safety data in UC and Crohn's to date has shown similar infection signals to Stelara, with no unexpected concerns. In the SEQUENCE Crohn's trial, serious adverse events occurred at similar rates between the two drugs. For skyrizi vs stelara UC side effects, the most common events are injection-site reactions, upper respiratory infections, and headache, all consistent with the class. Both drugs carry boxed warnings related to serious infections and both require TB and hepatitis B screening before starting.

Dosing and Administration

Skyrizi for UC uses IV induction at weeks 0, 4, and 8 (1200 mg per infusion), followed by subcutaneous maintenance of 180 mg or 360 mg every 8 weeks. Stelara uses a single weight-based IV induction dose, then 90 mg subcutaneous every 8 weeks. For UC patients comparing long-term convenience, both drugs share an every-8-week SC maintenance cadence. Skyrizi's three-dose IV induction is a bigger up-front infusion commitment than Stelara's single IV dose. Once patients are on maintenance, administration is similar. Patients who prefer minimizing infusion center visits during induction may lean toward Stelara. Those willing to invest in longer induction for the potential endoscopic benefits associated with p19 selectivity may lean toward Skyrizi.

Biologic-Experienced Patients

For UC patients who have failed an anti-TNF, both drugs have demonstrated efficacy but neither has been directly compared head-to-head in this population. SEQUENCE showed Skyrizi superior to Stelara in anti-TNF experienced Crohn's patients, and the p19-first prescribing trend in Crohn's is increasingly extending to UC. Gastroenterologists who extrapolate from SEQUENCE often reach for Skyrizi after anti-TNF failure in UC, even without direct trial data. Others prefer to follow UC-specific evidence and consider Stelara or Entyvio equally reasonable second-line options. Real-world registries over the next few years will clarify whether SEQUENCE-style superiority holds in UC.

Choosing With Your GI

For a UC patient choosing between Skyrizi and Stelara, the decision today rests largely on mechanistic extrapolation from Crohn's data, cross-trial indirect comparisons, and access factors. Skyrizi's p19 selectivity may deliver stronger endoscopic outcomes, though this has not been directly proven in UC head-to-head data. Stelara has a longer track record in UC, now includes a biosimilar option for lower cost, and may be easier to access on many insurance plans. Ask your GI how response will be measured after induction (typically week 12 to 16 for both drugs), what to do if symptoms persist, and whether cost or insurance coverage favors one option. A log of stool frequency, urgency, blood, and any new symptoms between visits gives your care team the data to recognize early loss of response before a full flare.