Reviewed on 4/8/2022

What Is Guselkumab and How Does It Work?

Guselkumab is a prescription medicine used in adults to treat psoriatic arthritis and moderate to severe plaque psoriasis who are candidates for systemic therapy or phototherapy.

  • Guselkumab is available under the following different brand names: Tremfya

What Are Dosages of Guselkumab?

Adult dosage

Injectable solution

Prefilled syringe, single-dose

  • 100mg/mL

One-Press patient-controlled injector, single-dose

  • 100mg/mL

Plaque Psoriasis

Adult dosage

  • 100 mg SC at Week 0, Week 4, and every 8 weeks thereafter

Psoriatic Arthritis

Adult dosage

  • 100 mg SC at Week 0, Week 4, and every 8 weeks thereafter
  • It may be administered alone or in combination with a conventional disease-modifying antirheumatic drug (cDMARD) (e.g., methotrexate)

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”


Psoriasis causes the top layer of skin cells to become inflamed and grow too quickly and flake off. See Answer

What Are Side Effects Associated with Using Guselkumab?

Common side effects of Guselkumab include:

  • headache, 
  • joint pain (arthralgia),
  • upper respiratory infections,
  • diarrhea, 
  • stomach pain;
  • cold symptoms such as stuffy nose, sneezing, sore throat,
  • cough, 
  • feeling short of breath,
  • skin infections, and
  • pain, itching, swelling, redness, or bruising at the injection site.

Serious side effects of Guselkumab include:

  • fever, 
  • chills, 
  • body aches, 
  • night sweats,
  • weight loss,
  • feeling very tired,
  • cough (may contain blood or mucus), 
  • shortness of breath,
  • pain or burning when urinating,
  • severe diarrhea or stomach cramps,
  • skin redness, tingling, blisters, oozing, or sores that look different from psoriasis,
  • stomach flu (gastroenteritis),
  • fungal skin infections, and
  • herpes simplex infections.

Rare side effects of Guselkumab include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Guselkumab?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Guselkumab has severe interactions with no other drugs.
  • Guselkumab has serious interactions with at least 21 other drugs.
  • Guselkumab has moderate interactions with at least 31 other drugs.
  • Guselkumab has minor interactions with no other drugs. 

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Guselkumab?


  • History of serious hypersensitivity reaction to guselkumab or any of the excipients

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Guselkumab?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Guselkumab?”


  • May increase infection risk; consider risks and benefits in patients with a chronic infection or history of recurrent infection; discontinue drug if a patient develops a serious infection or is not responding to therapy; treatment should not be initiated in patients with any clinically important active infection until the infection resolves or is adequately treated
  • Serious hypersensitivity reactions, including anaphylaxis, were reported with postmarket use; some cases required hospitalization; if a serious hypersensitivity reaction occurs, discontinue the drug and initiate appropriate therapy
  • Do not initiate in patients with a clinically important active infection until the infection resolves or is adequately treated
  • Screen for tuberculosis (TB) before initiating treatment; initiate treatment for latent TB before administering guselkumab; monitor patients for signs and symptoms of active TB during and after treatment
  • Consider completion of all age-appropriate immunizations before initiating guselkumab; avoid live vaccines
  • Drug interaction overview
  • Avoid the use of live vaccines
  • CYP450 substrates
  • The formation of CYP450 enzymes can be altered by increased levels of certain cytokines (eg, interleukin [IL]-1, IL-6, IL-10, tumor necrosis factor-alpha, interferon) during chronic inflammation
  • Guselkumab may modulate serum levels of some cytokines
  • Therefore, upon initiating or discontinuing guselkumab in patients who are receiving concomitant drugs that are CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for effect (eg, for warfarin) or drug concentration (eg, for cyclosporine) and consider dosage modification of the CYP450 substrate

Pregnancy and Lactation

  • There is a pregnancy registry that monitors pregnancy outcomes in women exposed to the drug during pregnancy; encourage patients to enroll by calling 1-877-311- 8972
  • No available data on use in pregnant women to inform a drug-associated risk of adverse developmental outcomes
  • Human IgG antibodies are known to cross the placental barrier; therefore, guselkumab may be transmitted from the mother to the developing fetus
  • Lactation
    • Unknown if distributed in human breast milk; maternal IgG is known to be present in human milk
    • Guselkumab was not detected in the milk of lactating cynomolgus monkeys
    • Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug, and any potential adverse effects on the breastfed infant from the drug or the underlying maternal condition 


Types of Psoriasis: Medical Pictures and Treatments See Slideshow
Medscape. Guselkumab.

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