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Generic name: guselkumab
Brand name: Tremfya
Dosage form: subcutaneous injection
Drug class: Interleukin inhibitors

Medically reviewed by Philip Thornton, DipPharm. Last updated on Apr 4, 2023.

What is guselkumab?

Guselkumab is an injectable medication used to treat two inflammatory, autoimmune conditions called plaque psoriasis and psoriatic arthritis.

Guselkumab is a type of biological drug called a human immunoglobulin G1 lambda (IgG1λ) monoclonal antibody. It works by blocking the action of interleukin-23 (IL-23) at its receptor. IL-23 is a naturally occurring small protein called a cytokine, which plays a role in your normal inflammatory and immune responses. By blocking the action of IL-23, guselkumab inhibits the release of small proteins called chemokines and cytokines that cause inflammation.

Guselkumab was first approved by the US Food and Drug Administration (FDA) in 2017. It comes in the form of a prefilled syringe and a One-Press injector.

No biosimilars of guselkumab have been approved. Biosimilars are highly similar versions of a biological drug that are designed to work in the same was as the original version of the drug, but they are not identical.

What is guselkumab used for?

Guselkumab is a prescription medicine used to treat adults:

  • with moderate to severe plaque psoriasis who may benefit from taking injections or pills (systemic therapy) or phototherapy (treatment using ultraviolet or UV light)
  • with active psoriatic arthritis (PsA).

It is not known if guselkumab is safe and effective in children under 18 years of age.

Important information

Guselkumab may cause serious side effects, including:

  • Serious allergic reactions. Stop using guselkumab and get emergency medical help right away if you develop any of the following symptoms of a serious allergic reaction:
    • fainting, dizziness, feeling lightheaded (low blood pressure)
    • swelling of your face, eyelids, lips, mouth, tongue or throat
    • trouble breathing or throat tightness
    • chest tightness
    • skin rash, hives
    • itching
  • Infections. Guselkumab is a medicine that may lower the ability of your immune system to fight infections and may increase your risk of infections. Your healthcare provider should check you for infections and tuberculosis (TB) before starting treatment with guselkumab and may treat you for TB before you begin treatment with guselkumab if you have a history of TB or have active TB. Your healthcare provider should watch you closely for signs and symptoms of TB during and after treatment with guselkumab.

    Tell your healthcare provider right away if you have an infection or have symptoms of an infection, including:
    • fever, sweats, or chills
    • cough
    • shortness of breath
    • blood in your phlegm (mucus)
    • muscle aches
    • warm, red, or painful skin or sores on your body different from your psoriasis
    • weight loss
    • diarrhea or stomach pain
    • burning when you urinate or urinating more often than normal

See "What are the side effects of guselkumab?" below for more information about side effects.

Who should not use guselkumab?

Do not use guselkumab if you have had a serious allergic reaction to guselkumab or any of the other ingredients in guselkumab. See below for a complete list of ingredients in guselkumab.

What should I tell my doctor before using guselkumab?

Before using guselkumab, tell your healthcare provider about all of your medical conditions, including if you:

  • have any of the conditions or symptoms listed in the section "Important information" above.
  • have an infection that does not go away or that keeps coming back.
  • have TB or have been in close contact with someone with TB.
  • have recently received or are scheduled to receive an immunization (vaccine). You should avoid receiving live vaccines during treatment with guselkumab.

How should I use guselkumab?

  • Use guselkumab exactly as your healthcare provider tells you to use it.
  • See the detailed "Instructions for Use" that comes with guselkumab for information on how to prepare and inject a dose of guselkumab, and how to properly throw away (dispose of) used guselkumab prefilled syringes or One-Press injectors.
  • Prepare for your injection
    • Remove your guselkumab prefilled syringe or One-Press injector carton from the refrigerator.
    • Keep the prefilled syringe or One-Press injector in the carton and let it sit on a flat surface at room temperature for at least 30 minutes before use.
    • Do not warm the prefilled syringe or One-Press injector any other way.
    • Check the expiration date ('EXP') on the back panel of the carton.
    • Do not use your prefilled syringe or One-Press injector if the expiration date has passed.
    • Do not inject guselkumab if the perforations on the carton are broken. Call your healthcare provider or pharmacist for a refill.
  • Choose injection site
    • Select from the following areas for your injection:
      • Front of thighs (recommended)
      • Lower stomach area (lower abdomen), except for a 2-inch area right around your navel (belly-button)
      • Back of upper arms (only if someone else is giving you the injection)
        Do not inject into skin that is tender, bruised, red, hard, thick, scaly or affected by psoriasis.
  • Clean injection site
    • Wash your hands well with soap and warm water.
    • Wipe your chosen injection site with an alcohol swab and allow it to dry.
    • Do not touch, fan, or blow on the injection site after you have cleaned it.
  • Inspect liquid
    • Take your guselkumab prefilled syringe or One-Press injector out of the carton.
    • Check the guselkumab prefilled syringe or One-Press injector liquid in the viewing window. It should be clear to slightly yellow and may contain tiny white or clear particles. You may also see one or more air bubbles. This is normal.
    • Do not inject if the liquid is cloudy or discolored, or has large particles. Call your healthcare provider or pharmacist for a refill.
  • Inject. guselkumab
    • Using prefilled syringe
      • Remove needle cover.
      • Hold your prefilled syringe by the body and pull needle cover straight off. It is normal to see a drop of liquid.
      • Inject guselkumab within 5 minutes of removing the needle cover.
      • Do not put needle cover back on, as this may damage the needle or cause a needle stick injury.
      • Do not touch needle or let it touch any surface.
      • Do not use a guselkumab prefilled syringe if it is dropped. Call your healthcare provider or pharmacist for a refill.
      • Position fingers and insert needle.
      • Place your thumb, index and middle fingers directly under the finger flange, as shown.
      • Do not touch plunger or area above finger flange as this may cause the needle safety device to activate.
      • Use your other hand to pinch skin at the injection site. Position syringe at about a 45 degree angle to the skin.
      • It is important to pinch enough skin to inject under the skin and not into the muscle.
      • Insert needle with a quick, dart-like motion.
      • Release pinch and reposition hand
      • Use your free hand to grasp the body of the prefilled syringe.
      • Press plunger
      • Place thumb from the opposite hand on the plunger and press the plunger all the way down until it stops.
      • Release pressure from plunger
      • The safety guard will cover the needle and lock into place, removing the needle from your skin.
    • Using a One-Press injector
      • Twist and pull off bottom cap
      • Keep hands away from the needle guard after the cap is removed.
      • Inject guselkumab within 5 minutes of removing the cap.
      • Do not put the cap back on, this could damage the needle.
      • Do not use a One-Press injector if it is dropped after removing the cap. Call your healthcare provider or pharmacist for a new One-Press injector.
      • Place on skin
      • Position the One-Press injector straight onto the skin (about 90 degrees relative to injection site).
      • Push handle straight down
      • Medication injects as you push. Do this at a speed that is comfortable for you.
      • Do not lift the One-Press injector during the injection. The needle guard will lock and the full dose will not be delivered.
      • Complete injection
      • Injection is complete when the handle is pushed all the way down, you hear a click, and the teal body is no longer visible.
      • Lift straight up
      • The yellow band indicates that the needle guard is locked.
  • After your injection
    • Dispose of your prefilled syringe or One-Press injector
    • Put your used guselkumab prefilled syringe or One-Press injector in an FDA-cleared sharps disposal container right away after use.
    • Do not throw away (dispose of) your guselkumab prefilled syringe or One-Press injector in your household trash.
    • Do not recycle your used sharps disposal container.
    • For more information, see "How should I dispose of the used prefilled syringe or One-Press injector? under Storage below.
  • Check injection site
    • There may be a small amount of blood or liquid at the injection site. Hold pressure over your skin with a cotton ball or gauze pad until any bleeding stops.
    • Do not rub the injection site.
    • If needed, cover injection site with a bandage.

What happens if I miss a dose?

If you miss your guselkumab dose, inject a dose as soon as you remember. Then, take your next dose at your regular scheduled time. Call your healthcare provider if you are not sure what to do.

What happens if I overdose?

If you inject more guselkumab than prescribed, call your healthcare provider right away.

Dosing information

In patients with plaque psoriasis and psoriatic arthritis the recommended dose of guselkumab is 100 mg administered by subcutaneous injection at Week 0, Week 4 and every 8 weeks thereafter. In patients with psoriatic arthritis, guselkumab can be used alone or in combination with a conventional disease-modifying antirheumatic drugs (DMARDs) such as methotrexate.

See full prescribing information for further information about guselkumab dosing.

What are the side effects of guselkumab?

Guselkumab may cause serious side effects including:

  • See "Important information" above.

The most common side effects of guselkumab include:

  • upper respiratory infections
  • joint pain (arthralgia)
  • fungal skin infections
  • headache
  • diarrhea
  • herpes simplex infections
  • injection site reactions
  • stomach flu (gastroenteritis)
  • bronchitis

These are not all the possible side effects of guselkumab. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Pregnancy and breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant. It is not known if guselkumab can harm your unborn baby.

Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known if guselkumab passes into your breast milk.


  • Store guselkumab in refrigerator at 36° to 46°F (2° to 8°C).
  • Do not freeze guselkumab prefilled syringes or One-Press injector.
  • Do not shake your guselkumab prefilled syringe or One-Press injector.
  • Keep guselkumab prefilled syringe or One-Press injector in the original carton to protect from light and physical damage.

Keep guselkumab prefilled syringe or One-Press injector and all medicines out of reach of children.

How should I dispose of the used prefilled syringe or One-Press injector?

If you do not have an FDA-cleared sharps disposal container, you may use a household container that is:

  • made of a heavy-duty plastic
  • can be closed with a tight-fitting, puncture-resistant lid, without sharps being able to come out
  • upright and stable during use
  • leak-resistant
  • properly labeled to warn of hazardous waste inside the container

When your sharps disposal container is almost full, you will need to follow your community guidelines for the right way to dispose of your sharps disposal container. There may be state or local laws about how you should throw away used needles and syringes.

For more information about safe sharps disposal, and for specific information about sharps disposal in the state that you live in, go to the FDA's website at:

What are the ingredients in guselkumab?

Active ingredient: guselkumab

Inactive ingredients: L-histidine, L-histidine monohydrochloride monohydrate, polysorbate 80, sucrose and water for injection

Not made with natural rubber latex.

Guselkumab is manufactured under the brand name Tremfya by Janssen Biotech, Inc., Horsham, PA 19044, U.S.

Popular FAQ

Yes, Tremfya is a biological medicine approved to treat adults with moderate-to-severe plaque psoriasis and psoriatic arthritis. A biological medicine is a large complex molecule made from living organisms using specialized technology. Tremfya works by blocking interleukin 23 (IL-23). Continue reading

More FAQ

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.