Guselkumab (Tremfya)

What is guselkumab?

Guselkumab (Tremfya) is an injectable biologic medication used in dermatology for moderate-to-severe plaque psoriasis and psoriatic arthritis. It is part of the IL-23 biologic class and is commonly considered for patients who need systemic treatment beyond topical medications or phototherapy.

It is one of the more established IL-23 biologics and is often part of the discussion when patients want a targeted psoriasis treatment with a longer maintenance interval after the starting doses.

How does guselkumab work?

Guselkumab targets interleukin-23 (IL-23), an inflammatory signal that helps drive psoriasis and psoriatic arthritis. By blocking IL-23, guselkumab can reduce inflammation, scaling, and plaque formation while also helping some patients with associated joint disease.

Because IL-23 is upstream in the inflammatory pathway, these medications are often discussed as highly targeted psoriasis therapies rather than broad immune suppressants.

What are possible side effects of guselkumab?

Possible side effects can include:

  • Upper respiratory symptoms

  • Headache

  • Injection site reactions

  • Mild fungal infections in some patients

As with other biologic medications, infection screening, vaccination review, and overall treatment risks should be discussed with the prescribing clinician. Patients should also mention any history of recurrent infections or chronic infection risk factors.

How is guselkumab used?

Guselkumab is given by injection on a schedule directed by your provider. Some patients may be able to self-inject at home after training. The medication is stored in the refrigerator.

For patients comparing biologics, guselkumab is often grouped with other IL-23 treatments and may be appealing because of its maintenance dosing schedule after the starting doses are completed. In real-world care, treatment selection may also depend on joint symptoms, prior biologic exposure, and insurance rules.

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