Skyrizi (risankizumab) works by blocking interleukin-23, a specific immune signaling protein that drives inflammation in conditions like psoriasis, Crohn’s disease, and ulcerative colitis. It’s a targeted biologic, meaning it zeroes in on one piece of the immune system rather than suppressing immunity broadly. This precision is what gives Skyrizi both its effectiveness and its relatively manageable side effect profile.
The Immune Pathway Skyrizi Targets
Your immune system uses small proteins called cytokines to coordinate its response to threats. One of these, interleukin-23 (IL-23), acts like a signal flare that activates a specific type of immune cell. Those activated cells then produce their own inflammatory chemicals, IL-17 and IL-22, which cause the visible and felt symptoms of autoimmune conditions: thickened, scaling skin in psoriasis, or ulceration and pain in inflammatory bowel disease.
Skyrizi is a lab-engineered antibody designed to latch onto the p19 subunit of IL-23 with high precision. Once it binds, IL-23 can no longer connect to its receptor on immune cells, which shuts down the downstream production of IL-17 and IL-22. The inflammation loses its fuel. Importantly, Skyrizi does not block IL-12, a related cytokine that shares part of IL-23’s structure. Older biologics that blocked both IL-12 and IL-23 cast a wider net; Skyrizi’s selectivity for IL-23 alone is a key part of its design.
Approved Uses
Skyrizi is FDA-approved for four conditions: moderate-to-severe plaque psoriasis in adults, active psoriatic arthritis, moderately to severely active Crohn’s disease, and moderately to severely active ulcerative colitis. The same core mechanism, blocking IL-23, applies across all four, but the dosing and delivery method differ significantly depending on the condition being treated.
How Effective It Is for Psoriasis
In real-world data from a three-year Italian study tracking patients with plaque psoriasis, about 54% achieved a 90% or greater improvement in their skin at 16 weeks. By one year, that number climbed to roughly 81%. Complete skin clearance, meaning no visible plaques at all, was reached by about 66% of patients after one year, 74% after two years, and 75% after three years. These results suggest that Skyrizi not only works quickly but continues to improve outcomes the longer people stay on it.
Results in Crohn’s Disease and Ulcerative Colitis
For Crohn’s disease, real-world data from an Asian cohort showed clinical remission rates building over the induction period: 12% at week 4, 22% at week 8, and 43% at week 12. Clinical remission in these studies meant disease activity had dropped below a threshold where patients experience minimal symptoms.
For ulcerative colitis, two randomized trials published in JAMA found that during the maintenance phase, about 40% of patients on Skyrizi achieved clinical remission compared to 25% on placebo. Clinical response rates, a broader measure that includes meaningful improvement short of full remission, reached 68% on Skyrizi versus 52% on placebo. Both differences were statistically significant.
How It’s Given and How Often
The dosing schedule depends entirely on which condition you’re treating. For plaque psoriasis, Skyrizi is a subcutaneous injection (under the skin) given at the start of treatment, again at week 4, and then once every 12 weeks. That works out to just four or five injections per year after the initial doses, which is less frequent than many competing biologics.
Crohn’s disease and ulcerative colitis require a more intensive start. The induction phase involves three intravenous (IV) infusions, each delivering 600 mg over at least an hour, given at weeks 0, 4, and 8. These are administered in a clinic or infusion center. After that, maintenance shifts to self-administered subcutaneous injections of 180 mg or 360 mg every 8 weeks. For Crohn’s disease, an on-body injector device is available as an alternative to a prefilled syringe, designed to stick to the abdomen or thigh and deliver the dose hands-free.
What to Expect Before Starting
Because Skyrizi partially suppresses immune function, your doctor will screen you for tuberculosis (TB) before prescribing it. If you have a history of latent or active TB that wasn’t fully treated, you may need to complete TB therapy before starting Skyrizi. You should not receive Skyrizi if you have active TB. Monitoring for signs of infection continues throughout treatment.
Side Effects and Long-Term Safety
Across 17 clinical trials, the most commonly reported side effects were upper respiratory infections, nasopharyngitis (common cold symptoms), joint pain, headache, and elevated blood pressure. These are generally mild and consistent with what’s seen across the biologic drug class.
The strongest safety data comes from the LIMMitless extension trial, which followed 897 psoriasis patients for up to six years of continuous Skyrizi use, accumulating nearly 5,000 patient-years of exposure. Over that period, rates of serious adverse events remained low and stable: serious infections occurred at a rate of about 1.1 per 100 patient-years, major cardiovascular events at 0.4 per 100 patient-years, and malignancies (excluding non-melanoma skin cancer) at 0.5 per 100 patient-years. Critically, none of these rates increased over time, and no new safety signals emerged. Nine deaths occurred during the study, all deemed unrelated to the drug by investigators. Only about 1.7% of patients discontinued due to side effects over the full six years.
This long-term profile is reassuring for a medication that many people will take indefinitely, since the conditions it treats are chronic and typically return if treatment stops.