What Is Tremfya, and Why Does It Matter?
Tremfya (guselkumab) is a lab-made, dual-acting antibody medication that reduces inflammation by targeting the interleukin-23 (IL-23) protein and blocking a majority of the cells that produce it. It is available by prescription. The FDA has now approved its under-the-skin injectable version for adults with moderate-to-severe ulcerative colitis (UC) for starting as well as continuing the treatment without the need for intravenous (IV) infusions.
Unlike previous IL-23 inhibitors that required IV infusions to start the therapy, Tremfya now offers both under-the-skin shots and IV options, making it easier for about 3 million people in the U.S. with UC or Crohn’s disease to begin and continue their therapy with convenient injections at home or in a clinic.
By reducing inflammation, this medicine provides relief from symptoms like continuous diarrhea, stomach pain, fatigue, weight loss, and rectal bleeding or bloody stools — making daily life more manageable. It offers a convenient option, especially if standard treatments like biologics or JAK inhibitors haven’t worked well for you or are unsuitable for certain reasons.
Tremfya is also FDA-approved for treating skin and joint conditions like plaque psoriasis and psoriatic arthritis.
Why Was It Approved?
This approval is based on a study that showed that starting treatment with this under-the-skin injectable form was safe and effective and that it started working at about the same time as the IV option in adults with moderate-to-severe UC whose condition hadn’t responded well to other treatments.
Patients saw symptom relief starting as early as two weeks, with improvements lasting through week 24. By week 12, 26% of patients receiving injectable Tremfya every four weeks vs. 7% of those getting a placebo achieved clinical remission. Similarly, 36% of those getting injectable Tremfya vs. 12% of those getting a placebo saw endoscopic healing. These results were similar to those seen with the previously approved IV version (clinical remission, 23% vs. 8%; endoscopic improvement, 27% vs. 11%).
At week 24, patients on maintenance injectable therapy also showed strong positive results, with 34% (vs. 10% with placebo) reaching clinical remission and up to 44% (vs. 12% with placebo) showing endoscopic improvement.
The most common side effects include redness, bruising, or pain where the injection is given, joint pain, a stuffy or runny nose, headache, stomach flu, tiredness, viral (herpes simplex) or fungal skin infections, fever, and skin rashes. More serious but less common risks include allergic reactions, liver problems, and infections, especially if you’ve had tuberculosis (TB) in the past.
What Do I Need to Know?
Tremfya is given in two stages: a starting phase (called induction) and a long-term phase (called maintenance). For UC, the starting dose is given as two shots under the skin at weeks 0, 4, and 8. After that, your health care provider will decide if you should continue with a shot every four or eight weeks, depending on your response.
You or your caregiver can give the medicine at home using a prefilled syringe or pen once you’ve been trained by your health care provider. If you miss your dose, take it as soon as you remember and stick to your schedule for the next dose. If you inject too much Tremfya, contact your health care provider at once. Keep the medicine in the refrigerator and don’t freeze or shake it.
Before you start taking the medicine, your health care provider will check for infections, including tuberculosis (TB). They will likely check your liver with blood tests before and during treatment, especially if you have Crohn’s disease and are using higher doses.
Inform your health care provider if you are being treated for an infection (including TB) or have an infection that does not go away or keeps coming back. You should not get live vaccines while using this medicine. It’s not known if Tremfya can harm a fetus or pass into breast milk. Talk to your health care provider if you are pregnant, planning pregnancy, or breastfeeding before starting this medicine.
You should not use this medicine if you’ve had a serious allergic reaction to it or to any of its ingredients. Let your provider know right away if you notice signs of infection, liver problems (like yellowing of your skin or eyes or dark urine), or allergic reactions (such as trouble breathing or swelling of your face, eyelids, lips, mouth, tongue, or throat; skin rashes; or hives).