Stelara

Stelara (ustekinumab) is a biologic injection that has been available since 2009 and remains one of the most versatile medicines for immune-mediated diseases. It is approved for moderate-to-severe plaque psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis. Its mechanism — blocking both IL-12 and IL-23 — is unique among biologics and explains its broad activity across different disease types.

Stelara belongs to the IL-12/23 Inhibitors class of medications. Ustekinumab is a human monoclonal antibody that binds the shared p40 subunit of interleukin-12 (IL-12) and interleukin-23 (IL-23), blocking their receptor interactions and reducing the Th1 and Th17 inflammatory pathways responsible for psoriasis, psoriatic arthritis, and inflammatory bowel disease. Understanding how Stelara works helps explain both its benefits and its characteristic safety profile.

## What Stelara is used for

Stelara is prescribed for Moderate-to-severe plaque psoriasis, Psoriatic arthritis, Crohn's disease, and Ulcerative colitis. For psoriasis, it is used when topical therapies and other systemic agents have not provided adequate control. For Crohn's disease and ulcerative colitis, it is used in patients with moderately to severely active disease. Stelara is available by prescription only and has been FDA-authorized since 2009.

## Dosage and administration

Typical adult dosing: Psoriasis (SC): 45 mg at weeks 0 and 4, then every 12 weeks; weight >100 kg: 90 mg on same schedule. Crohn's/UC induction: single IV dose based on body weight; maintenance: 90 mg SC every 8 weeks.

For plaque psoriasis, Stelara is given as two starter injections four weeks apart, then once every three months — a convenient, infrequent schedule that many patients appreciate. For Crohn's disease and UC, the induction phase requires a single weight-based IV infusion in a clinical setting, followed by subcutaneous maintenance injections every eight weeks. Available forms include Subcutaneous injection (prefilled syringe or autoinjector) and Intravenous infusion (IBD induction).

## Side effects

Common side effects include Nasopharyngitis, Upper respiratory infection, Headache, Fatigue, Injection-site reactions, and Back pain. Serious side effects include Serious infections, Tuberculosis reactivation, Reversible posterior leukoencephalopathy syndrome (RPLS — rare), Hypersensitivity reactions, and Malignancy. The most common side effects with Stelara are infections of the upper respiratory tract. Because Stelara affects immune function, there is a risk of serious infections, including reactivation of latent TB. RPLS is a rare but serious neurological side effect associated with Stelara; seek emergency care for sudden severe headache, confusion, or seizure. Seek emergency care for signs of a severe allergic reaction — hives, swelling of the face or throat, or difficulty breathing.

## Managing common side effects

• Nasopharyngitis/URI: rest and stay hydrated; seek care if symptoms worsen or include high fever.
• Headache: stay hydrated, rest, and use a simple analgesic if your clinician agrees it is safe.
• Fatigue: prioritize rest and good sleep hygiene; report persistent fatigue to your clinician.
• Injection-site reactions: rotate injection sites and allow the pen or syringe to reach room temperature before injecting.
• Back pain: gentle activity and over-the-counter analgesics may help; discuss persistent pain with your clinician.

## Warnings and precautions

Key precautions: Screen for TB before initiating and monitor during treatment; Monitor for signs of infection; Do not give live vaccines during treatment. Stelara is not suitable for active serious infections. Before starting, complete the vaccination schedule and discuss any history of recurring infections with your prescriber.

## Drug interactions

Stelara can interact with Live vaccines (major) — avoid during therapy; CYP450 substrates with narrow therapeutic index (moderate) — cytokine modulation may alter enzyme activity. Inform your prescriber and pharmacist of every drug, supplement, and herbal product you take.

## Cost, coverage, and savings

Stelara is a high-cost specialty biologic. Janssen offers a Stelara savings program ("Janssen CarePath") that can reduce costs for commercially insured patients. Uninsured or underinsured patients may qualify for patient assistance. Search for a stelara copay card, stelara savings card, or stelara patient assistance through Janssen's website for current offers. Note that biosimilar ustekinumab products have begun entering the market, which may offer lower-cost options.

## How Stelara compares to alternatives

Compared with Skyrizi (which only blocks IL-23), Stelara blocks both IL-12 and IL-23. In head-to-head psoriasis studies, Skyrizi generally achieves higher skin clearance rates (PASI 90/100), while Stelara's dual mechanism may be relevant for patients with comorbidities. For Crohn's disease, Stelara and Skyrizi are both approved maintenance options with similar remission rates in their trials. The best biologic depends on the specific condition, disease severity, prior therapy, and insurance coverage.

## Monitoring and lifestyle

Before starting Stelara, TB screening, complete blood count, and a thorough medication review are standard. During long-term treatment, clinicians monitor for infection signs, disease activity, and skin changes. Live vaccines should be updated before starting. A healthy lifestyle — balanced diet, adequate sleep, stress management, avoidance of smoking — supports better outcomes across all inflammatory conditions.

## What to expect from treatment

For plaque psoriasis, meaningful skin clearance typically begins by week 12, with continued improvement to week 24 and beyond. For IBD, clinical response during the induction phase (weeks 8–16) determines whether maintenance is appropriate. Stelara is a long-term therapy; stopping without medical guidance can trigger disease flare.

## Before you start Stelara

Pre-treatment workup includes TB test (PPD or IGRA), reviewing vaccination history, completing live vaccines, and CBC. For IBD, the initial infusion is given in a clinical setting. Bring a complete medication list so drug interactions can be screened.

## Missed dose and overdose

If you miss a subcutaneous Stelara dose, inject it as soon as you remember and then resume your regular schedule from that date. Do not give two doses to make up for a missed one. For IV infusions, contact your care team to reschedule. If overdose is suspected, contact poison control or emergency services.

## Use in specific populations

Pregnancy: Use with caution — limited human data; discuss risks and benefits with your clinician. Breastfeeding: May be present in breast milk; consult your clinician. Older adults: May be at higher risk for infections. Pediatric use: Stelara is approved for children ≥6 years with moderate-to-severe plaque psoriasis.

## When to contact your doctor

Contact your clinician for signs of infection (fever, chills, cough, skin sores), worsening of your underlying disease, sudden neurological symptoms (severe headache, confusion, vision changes), or any new or unusual symptoms after starting Stelara.

## Storage and handling

Refrigerate at 2–8°C (36–46°F). Do not freeze. Protect from light. Store in original packaging until ready to use. Do not use if the solution is discolored or contains particles.

## Clinical evidence and effectiveness

Stelara's efficacy across its four approved indications is backed by multiple phase 3 trials. For psoriasis (PHOENIX-1, PHOENIX-2), response rates of PASI 75 exceeded 66–76% at week 28. For Crohn's disease (UNIFI for UC; UNIFI CD program), Stelara achieved clinical remission rates superior to placebo in both induction and maintenance. Long-term extension data confirm sustained benefit for many patients over years of use.

## Key takeaways

• Stelara blocks both IL-12 and IL-23, offering broad activity across psoriasis, psoriatic arthritis, Crohn's disease, and UC.
• Every-12-week maintenance dosing for psoriasis is one of the least frequent injection schedules among biologics.
• TB screening is required before starting.
• Biosimilar ustekinumab products are entering the market and may offer lower-cost alternatives.
• Manufacturer savings programs can reduce costs for eligible commercially insured patients.

## Medical disclaimer

This article about Stelara (ustekinumab) is for general education and is not a substitute for professional medical advice, diagnosis, or treatment. Always follow the guidance of your physician or pharmacist and the instructions on your prescription label.