Stelara

How Does Stelara Work?

Stelara (ustekinumab) is a fully human IgG1κ monoclonal antibody that works by binding to the p40 protein subunit shared by interleukin-12 (IL-12) and interleukin-23 (IL-23) — two cytokines (chemical messenger proteins) produced by the immune system that play a central role in driving inflammation in autoimmune conditions. By blocking p40, ustekinumab prevents both IL-12 and IL-23 from binding to their receptors on immune cell surfaces.

This dual blockade prevents the activation of inflammatory T-cell pathways — specifically the Th1 pathway (activated by IL-12) and the Th17 pathway (activated by IL-23) — that are central to the pathology of psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis. By interrupting these signals, Stelara reduces the inflammatory cascade that causes visible skin plaques, joint damage, and intestinal inflammation.

Unlike broadly-acting immunosuppressants such as steroids or methotrexate, Stelara targets a very specific part of the immune system. Unlike TNF inhibitors (Humira, Remicade), it targets a different inflammatory pathway. And unlike newer selective IL-23 inhibitors (Skyrizi, Tremfya) that target only IL-23, Stelara uniquely targets both IL-12 and IL-23 through their shared p40 subunit.

How Hard Is It to Find Stelara in Stock?

Stelara is not on the FDA's official drug shortage list in 2026, and supply is generally available through the specialty pharmacy network. However, patients frequently encounter real-world access barriers because Stelara is a specialty medication — it cannot be picked up at a standard retail pharmacy and requires prior authorization from your insurance company before it can be dispensed.

The main access challenges in 2026 are insurance-related: most commercial plans have dropped brand Stelara from preferred formulary positions in favor of biosimilar versions, and which biosimilar is covered varies significantly by insurance plan and pharmacy benefit manager (PBM). Exclusive pharmacy distribution deals — such as Wezlana being available only through Optum Specialty Pharmacy — further complicate access for some patients.

If you're having difficulty locating your ustekinumab prescription, medfinder contacts specialty pharmacies on your behalf to find which ones can fill your prescription, texting you results so you don't have to make dozens of calls yourself.

Who Can Prescribe Stelara?

Stelara (ustekinumab) is not a controlled substance, so any licensed prescriber may technically write a prescription. However, because initiating biologic therapy requires pre-treatment TB screening, disease severity assessment, and insurance prior authorization expertise, Stelara is almost always initiated by specialists with experience in biologic prescribing.

Dermatologists — primary prescribers for plaque psoriasis and psoriatic arthritis with skin predominance

Rheumatologists — primary prescribers for psoriatic arthritis and inflammatory joint conditions

Gastroenterologists — primary prescribers for Crohn's disease and ulcerative colitis

Pediatric specialists — pediatric dermatologists and gastroenterologists manage Stelara for eligible children

Nurse Practitioners and Physician Assistants — in most states, NPs and PAs working in specialty practices have authority to prescribe biologics including Stelara

Telehealth is available for established Stelara patients in many practices for follow-up and prescription management. Initial prescriptions typically require an in-person visit for TB testing, physical examination, and disease severity assessment. Dedicated telehealth dermatology and GI platforms are expanding but may have limitations for biologic initiation.

Is Stelara a Controlled Substance?

No. Stelara (ustekinumab) is not a controlled substance and is not scheduled by the DEA. It does not have abuse potential and does not require the special prescribing, storage, or dispensing restrictions associated with controlled substances like opioids or benzodiazepines.

However, Stelara is a specialty biologic that requires a prescription from a licensed healthcare provider and prior authorization from insurance before it can be dispensed. It must be dispensed by a specialty pharmacy due to its handling requirements (cold storage, special packaging). Prescriptions can be written by any licensed prescriber, but in practice, initiation is managed by specialists — dermatologists, rheumatologists, or gastroenterologists — with experience in biologic therapy.

Common Side Effects of Stelara

Common side effects (reported in ≥3% of patients):

Nasopharyngitis (runny nose, sore throat, nasal congestion)

Upper respiratory tract infections

Headache

Fatigue

Injection site reactions (redness, pain, bruising)

Nausea (especially in IBD patients)

Sinusitis and bronchitis

Serious Side Effects

Serious infections (bacterial, fungal, viral, mycobacterial) — including TB reactivation

Posterior Reversible Encephalopathy Syndrome (PRES) — rare but serious; symptoms include sudden severe headache, confusion, seizures

Serious allergic reactions including anaphylaxis and angioedema

Increased risk of malignancy (including non-melanoma skin cancers)

Latex allergy reaction (prefilled syringe needle cover contains latex)

Final Thoughts on Stelara

Stelara (ustekinumab) has proven itself over more than 15 years as an effective treatment for plaque psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis. Its unique mechanism of targeting both IL-12 and IL-23 through the shared p40 subunit gives it a distinct profile among biologics, and its every-12-week dosing schedule (every-8-weeks for IBD maintenance) makes it one of the more convenient biologic options available.

In 2026, the availability picture has fundamentally shifted. With eight FDA-approved biosimilars on the market at 80-95% lower prices, ustekinumab has never been more affordable — though navigating which biosimilar your insurance covers, and in which specialty pharmacy network, remains the primary access challenge. For patients whose plan has dropped brand Stelara, switching to a covered biosimilar often makes clinical and financial sense, as all interchangeable biosimilars have demonstrated comparable safety and effectiveness.

If you're struggling to fill your ustekinumab prescription, medfinder can help you find which specialty pharmacies can fill your prescription — so you spend less time on hold and more time on your health. Enter your medication, dosage, and location to get started.