Guselkumab
Interleukin inhibitors
Interleukin inhibitors
A human antibody against the p19 subunit of interleukin-23, injected for plaque psoriasis, psoriatic arthritis, Crohn's disease and ulcerative colitis.
Quick facts
- Group
- Interleukin inhibitors
- Target
- Interleukin-23, p19 subunit (IL-23p19)
- Used for
- Moderate to severe plaque psoriasis · Crohn's disease
- Key effects
- Headache · Injection-site reactions · Joint pain
- Monitor
- Latent tuberculosis test before starting
- ATC
- L04AC16
No doses: the clinician sets them by the current guideline.
Mechanism of action
Guselkumab is a human IgG1 monoclonal antibody that binds the p19 subunit found only in interleukin-23. IL-23 keeps Th17 cells active; with it neutralised, less IL-17 and other inflammatory cytokines are made in the skin, joints and gut. Unlike ustekinumab, it spares IL-12, which shares only the p40 subunit.
- Antibody binds the p19 subunit of IL-23
- IL-23 can no longer sustain Th17 cells
- Less IL-17 and related cytokines
- Psoriasis plaques, joints and gut inflammation improve
Indications
- Moderate to severe plaque psoriasis Psoriasis →
- Psoriatic arthritis Psoriatic arthritis →
- Ulcerative colitis Ulcerative colitis →
- Crohn's disease Crohn disease →
Adverse effects
Common
- Headache
- Injection-site reactions
- Joint pain
- Diarrhoea, nausea or abdominal pain
Contraindications
- Hypersensitivity to guselkumab
- Active serious infection, including active tuberculosis
Key interactions
- Live vaccines
- Avoided during treatment; age-appropriate vaccines are given before starting.
- Other immunosuppressants and biologics
- Added infection risk.
What is monitored
- Latent tuberculosis test before starting
- Liver tests and liver symptoms
- Signs of infection
Administration and safety
- Injected under the skin; the patient or a caregiver can inject at home after teaching.
- Vaccines are brought up to date before starting.
- The dose is delayed during an active infection, after the team's review.
Pregnancy and breastfeeding
Human data are limited; pregnancy and breastfeeding are discussed with the treating team.
Nursing care
- Confirm the tuberculosis test before the first dose.
- Teach to report fever, chills, cough or painful urination.
- Teach to report yellow skin or eyes, dark urine or upper right abdominal pain.
Pharmacokinetics
- Absorption
- Subcutaneous injection; an intravenous form also exists
- Metabolism
- Broken down like other antibodies
Test yourself
Think of the answer, then tap the question to see it.
Which subunit does guselkumab bind?
The p19 subunit, unique to interleukin-23.
How does guselkumab differ from ustekinumab?
Ustekinumab binds p40, shared by IL-12 and IL-23; guselkumab binds p19 and blocks only IL-23.
Which infection test is done before guselkumab?
A test for latent tuberculosis.
Connections
← Back to the class: Interleukin inhibitors
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Guselkumab Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.