By Counterforce Health Team —

Unlocking Relief: What You Need to Know About Tremfya (Guselkumab)

If you're living with a chronic inflammatory condition, you've likely heard of biologic therapies. Among the newer options is Tremfya (guselkumab), a treatment that's changing the game for many people.

This post will break down what Tremfya is, how it works, what it treats, and key safety information.

What is Tremfya and How Does it Work?

Tremfya is a type of biologic medicine called a monoclonal antibody. It's specifically an interleukin-23 (IL-23) blocker.

The Mechanism of Action

To understand Tremfya, you need to know about IL-23. This is a naturally occurring protein (a cytokine) in the body that plays a crucial role in regulating inflammatory and immune responses. In certain autoimmune and inflammatory diseases, IL-23 is overactive, leading to chronic inflammation.

Tremfya works by selectively binding to the p19 subunit of the IL-23 protein. By blocking IL-23, Tremfya disrupts the inflammatory cascade (specifically the IL-23/Th17 pathway) that drives symptoms. This targeted approach helps to reduce inflammation, clear skin plaques, and ease joint symptoms.

Conditions Treated by Tremfya

Tremfya is approved to treat several significant inflammatory conditions:

  • Moderate to Severe Plaque Psoriasis: A chronic skin condition characterized by red, raised, scaly patches called plaques. Tremfya is often prescribed for adults and some pediatric patients who are candidates for systemic therapy (pills or injections) or phototherapy.
  • Active Psoriatic Arthritis (PsA): This is a type of arthritis that can occur in people with psoriasis. It causes joint pain, stiffness, and swelling. Tremfya can be used alone or in combination with conventional disease-modifying antirheumatic drugs (DMARDs) like methotrexate.
  • Moderately to Severely Active Ulcerative Colitis (UC): A type of inflammatory bowel disease (IBD) that causes long-lasting inflammation and ulcers in the large intestine (colon) and rectum.
  • Moderately to Severely Active Crohn's Disease (CD): Another type of IBD that can affect any part of the digestive tract from mouth to anus.

Administration and Dosing

Tremfya is administered via subcutaneous injection (under the skin).

For plaque psoriasis and psoriatic arthritis, the typical dosing is:

  • A starting dose at Week 0, followed by a second dose at Week 4.
  • Maintenance doses are then typically given every 8 weeks thereafter.

For ulcerative colitis and Crohn's disease, the initial doses (induction) are typically administered more frequently, with a maintenance dose following thereafter.

The injection can be given by a healthcare professional, or you may be trained to self-inject at home using a prefilled syringe or a patient-controlled injector, which offers convenience for long-term management.

Important Safety Considerations

Like all powerful medications, Tremfya carries potential side effects and risks. It's crucial to discuss your full medical history with your healthcare provider before starting treatment.

Common Side Effects

The most frequently reported side effects include:

  • Respiratory tract infections (like the common cold or bronchitis)
  • Headache
  • Injection site reactions (redness, pain, or swelling at the injection area)
  • Joint pain (arthralgia)
  • Diarrhea or stomach flu (gastroenteritis)

Serious Risks and Warnings

Because Tremfya modulates the immune system, it can increase the risk of certain serious conditions:

  1. Infections: Tremfya can lower your immune system's ability to fight infections. Your doctor should test you for tuberculosis (TB) before starting treatment and will monitor you for signs of new infections throughout therapy.
  2. Serious Allergic Reactions: Though rare, serious allergic reactions (including anaphylaxis) can occur. Symptoms like swelling of the face, tongue, or throat, or trouble breathing require immediate medical attention.
  3. Liver Problems: For patients treated for UC or Crohn's disease, and in some cases for psoriasis and PsA, your doctor will perform blood tests to check your liver before and during treatment.

Always tell your doctor immediately if you develop symptoms of a serious infection (e.g., fever, sweats, persistent cough, unexplained weight loss) or signs of liver problems (e.g., yellowing of the skin or eyes, dark urine, severe fatigue).

Before starting Tremfya, ensure all your age-appropriate vaccinations are up to date, and avoid live vaccines while on the medication.