Stelara Is Losing Market Share. Here Is What That Means for Your Formulary.

5 minute read

Johnson and Johnson's first-quarter 2026 earnings, reported on April 14, 2026, showed what the pharmaceutical industry has been watching unfold for more than a year: Stelara, once J&J's most lucrative drug with more than $10 billion in annual sales, is in rapid decline as biosimilar competition accelerates.¹ In its place, Tremfya, a newer medication that treats many of the same conditions, posted first-quarter sales of $1.6 billion, a 74% increase over the same period last year.¹

This revenue shift is a business story. It is also a formulary story. And if you take Stelara for Crohn's disease, ulcerative colitis, plaque psoriasis, or psoriatic arthritis, the business story has direct implications for the coverage you hold.

What Is Happening to Stelara's Market Position

Stelara (ustekinumab) is a biologic that works by blocking interleukin-12 and interleukin-23, two proteins involved in the inflammatory processes underlying several immune-mediated conditions. It has been on the market since 2009 and became the standard of care for many patients with moderate to severe Crohn's disease, ulcerative colitis, plaque psoriasis, and psoriatic arthritis.

Biosimilar competition for ustekinumab began in earnest in 2024, after J&J's core patents expired. Multiple biosimilars referencing Stelara are now on the U.S. market, and CMS added ustekinumab to Medicare Part D's list of drugs eligible for Inflation Reduction Act price negotiation for the 2026 plan year. The combination of biosimilar alternatives and negotiated pricing has significantly reduced Stelara's cost advantage for payers, who have responded by restructuring their formularies around the cheaper alternatives.¹

What Tremfya Is and How It Differs

Tremfya (guselkumab) is a more targeted biologic. Where Stelara blocks both IL-12 and IL-23, Tremfya specifically targets IL-23. The clinical significance of that distinction is an active area of research, but in practice, Tremfya is cleared for plaque psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis, the same core indications as Stelara.

J&J has an obvious incentive to migrate prescribers and payers toward Tremfya: it is still under patent protection, which means it remains a higher-margin product for the company and does not yet face biosimilar competition. Payers have their own incentive to favor Tremfya in some cases, because biosimilar ustekinumab, while cheaper, introduces administrative complexity around which biosimilar to prefer.

The result is a formulary landscape that is moving in several directions at once. Some plans are moving to preferred ustekinumab biosimilars as the lowest-cost option for Stelara patients. Others are moving toward Tremfya as their preferred IL-23 inhibitor for new starts. Both movements affect patients who are stable on branded Stelara.

What This Means If You Currently Take Stelara

If you are currently stable on Stelara and your insurer has not yet contacted you about a formulary change, that does not mean a change is not coming. Most insurers update formularies at the plan year renewal, typically January 1 for commercial plans. Some issue mid-year notices when a biosimilar enters preferred status.

There are three coverage scenarios patients on Stelara are increasingly likely to encounter.

Non-medical switching to a ustekinumab biosimilar. Your plan moves biosimilar ustekinumab to preferred status and requires a new prior authorization if you want to continue on branded Stelara. In most cases, the clinical documentation required to justify continued use of the branded version is significant. Without a physician documenting a specific medical reason why the biosimilar is not appropriate for you, these prior authorizations are frequently denied.

Step therapy toward Tremfya. For patients whose coverage for Stelara lapses or who are newly diagnosed, some plans will now require trying Tremfya before approving Stelara. Tremfya is a different biologic with a related but distinct mechanism, so this is not technically a generic substitution, but step therapy policies do not require that drugs be identical, only that they treat the same condition.

Continued coverage with increased cost share. Some plans will keep Stelara on formulary but move it to a higher cost-share tier, effectively increasing your out-of-pocket cost without requiring a prior authorization change. This is legal and common, and it is how insurers create financial pressure toward biosimilar adoption without triggering the formal appeals process.

What You Can Do

Check your current formulary status. Log into your insurance portal, call member services, or ask your specialty pharmacy what tier Stelara currently sits on under your plan, and whether the plan has issued any biosimilar equivalency policies affecting ustekinumab.

Get your current prior authorization documented. If your Stelara coverage requires a prior authorization, request a written copy of the current approval, including its expiration date. Many patients do not know when their authorization expires until they receive a denial at the pharmacy counter.

Talk to your physician before your authorization expires. If you have been stable on Stelara and your physician believes a biosimilar switch or a transition to Tremfya is not medically appropriate for you, that clinical opinion needs to be in writing and on file before any coverage change takes effect. Step therapy exception requests and biosimilar opt-out requests are much harder to win retroactively.

Know the difference between interchangeable and non-interchangeable biosimilars. The FDA designates some biosimilars as "interchangeable," meaning a pharmacist can substitute them without contacting your prescriber. Not all ustekinumab biosimilars carry this designation. Ask your specialty pharmacy and your prescriber whether any automatic substitution has occurred or could occur at your next fill.

The Broader Pattern

When a major biologic comes off patent and biosimilars enter the market, the transition period is never seamless for patients who are stable on the branded drug. The financial incentives for payers and manufacturers do not align with clinical stability. What is right for the formulary spreadsheet is not always what is right for the patient who took two years to find a medication that works for a condition that does not respond to most treatments.

The good news is that patients who are stable on a specific biologic, and whose physicians document that stability clearly, have a strong basis for appealing formulary-driven non-medical switches. An insurer who requires you to fail a different medication before covering the one you are currently stable on is on questionable clinical ground, particularly for conditions like Crohn's disease and ulcerative colitis where remission is fragile and relapse is costly.

If your Stelara coverage has changed or your prior authorization is coming up for renewal, Ellen can help you understand the denial language, identify the relevant appeal criteria, or draft the documentation your physician needs to submit.

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