What is Guselkumab: Uses, Dosage, Side Effects and More

Guselkumab is a prescription medication that helps treat certain autoimmune conditions by targeting specific parts of your immune system. It belongs to a class of drugs called interleukin-23 inhibitors, which work by blocking proteins that cause inflammation in your body.

This medication is given as an injection under your skin, similar to how people with diabetes give themselves insulin shots. Your doctor will typically prescribe guselkumab when other treatments haven't worked well enough or when you need a more targeted approach to manage your condition.

What is Guselkumab Used For?

Guselkumab is primarily used to treat moderate to severe plaque psoriasis in adults. Plaque psoriasis is a chronic skin condition that causes thick, scaly patches to form on your skin, often on your elbows, knees, scalp, and back.

This medication is also approved to treat psoriatic arthritis, a condition where psoriasis affects your joints, causing pain, stiffness, and swelling. Some people have both skin psoriasis and joint problems, while others may only have the joint symptoms.

Your doctor might consider guselkumab if you've tried topical treatments, light therapy, or other medications without getting the relief you need. It's particularly helpful for people whose psoriasis covers a significant portion of their body or significantly impacts their quality of life.

How Does Guselkumab Work?

Guselkumab works by blocking a protein called interleukin-23 (IL-23) in your immune system. This protein normally helps coordinate your body's immune response, but in autoimmune conditions like psoriasis, it becomes overactive and causes too much inflammation.

Think of IL-23 as a messenger that tells your immune cells to create inflammation. When guselkumab blocks this messenger, it reduces the inflammatory signals that cause psoriasis symptoms. This helps slow down the rapid skin cell growth that creates those thick, scaly patches.

This medication is considered a targeted therapy, meaning it specifically focuses on one part of the immune system rather than broadly suppressing your entire immune response. This targeted approach can be more effective and may cause fewer side effects than some other immune-suppressing medications.

How Should I Take Guselkumab?

Guselkumab is given as an injection under the skin, typically in your thigh, upper arm, or abdomen. Your healthcare provider will teach you how to give yourself these injections at home, or a family member can learn to help you.

The usual starting dose is 100 mg given at weeks 0 and 4, then every 8 weeks after that. Your doctor will determine the exact schedule that's right for your condition. It's important to stick to this schedule even if you start feeling better, as consistency helps maintain the medication's effectiveness.

You can take guselkumab with or without food since it's injected rather than taken by mouth. Store the medication in your refrigerator, but let it come to room temperature before injecting it to make the injection more comfortable.

Before each injection, wash your hands thoroughly and clean the injection site with an alcohol swab. Rotate your injection sites to prevent irritation, and never inject into areas where your skin is tender, bruised, or affected by psoriasis.

How Long Should I Take Guselkumab For?

Guselkumab is typically a long-term treatment for chronic conditions like psoriasis and psoriatic arthritis. Most people need to continue taking it indefinitely to maintain their improvement, as these conditions don't have a permanent cure.

You might start seeing improvements in your skin within the first few weeks, but it can take up to 16 weeks to see the full benefits. Some people notice significant clearing of their psoriasis patches within 2-3 months of starting treatment.

Your doctor will monitor your progress through regular appointments and may adjust your treatment plan based on how well you're responding. If you stop taking guselkumab, your symptoms will likely return, often within a few months.

What Are the Side Effects of Guselkumab?

Like all medications, guselkumab can cause side effects, though many people tolerate it well. Understanding what to expect can help you feel more prepared and know when to contact your healthcare provider.

The most common side effects are generally mild and include reactions at the injection site. Here's what you might experience:

• Redness, swelling, or mild pain where you inject the medication
• Upper respiratory infections like colds or sinus infections
• Headaches that are usually mild and temporary
• Fatigue or feeling more tired than usual
• Joint pain, particularly in the first few weeks of treatment
• Diarrhea or mild stomach upset

These common side effects often improve as your body adjusts to the medication. However, you should contact your doctor if they persist or become bothersome.

More serious but less common side effects can occur because guselkumab affects your immune system. While these are rare, it's important to be aware of them:

• Serious infections that may require hospitalization
• Reactivation of dormant infections like tuberculosis or hepatitis B
• Allergic reactions including rash, itching, or difficulty breathing
• Inflammatory bowel disease symptoms like persistent diarrhea or abdominal pain
• Unusual changes in your skin or new growths

If you experience fever, persistent cough, flu-like symptoms, or any signs of infection, contact your healthcare provider right away. These could indicate that your immune system needs attention.

Who Should Not Take Guselkumab?

Guselkumab isn't suitable for everyone, and your doctor will carefully review your medical history before prescribing it. People with active infections should not start this medication until their infection is completely treated.

You should tell your doctor if you have a history of tuberculosis, hepatitis B or C, or other chronic infections. These conditions may become active again when your immune system is modified by guselkumab.

Pregnant or breastfeeding women should discuss the risks and benefits with their healthcare provider. While there's limited data on guselkumab during pregnancy, your doctor can help you weigh the potential benefits against any possible risks.

People who have received live vaccines recently should wait before starting guselkumab. Additionally, you should avoid live vaccines while taking this medication, though most routine vaccines are still safe to receive.

Guselkumab Brand Names

Guselkumab is available under the brand name Tremfya. This is currently the only brand name available for this medication in most countries.

When you pick up your prescription, you'll see "Tremfya" on the packaging and labeling. The medication comes in pre-filled syringes or auto-injector pens, making it easier to give yourself the injections at home.

Guselkumab Alternatives

If guselkumab isn't right for you, several other medications can treat psoriasis and psoriatic arthritis. Your doctor might consider other biologic medications that work in similar ways but target different parts of the immune system.

Other IL-23 inhibitors include risankizumab (Skyrizi) and tildrakizumab (Ilumya). These medications work similarly to guselkumab but may have different dosing schedules or side effect profiles that might be better suited to your needs.

TNF inhibitors like adalimumab (Humira), etanercept (Enbrel), and infliximab (Remicade) are another class of biologic medications that can be effective for psoriasis and psoriatic arthritis. These have been available longer and have extensive safety data.

IL-17 inhibitors such as secukinumab (Cosentyx) and ixekizumab (Taltz) represent another targeted approach. Your doctor will consider factors like your specific symptoms, other health conditions, and insurance coverage when choosing the best alternative.

Is Guselkumab Better Than Adalimumab?

Both guselkumab and adalimumab are effective treatments for psoriasis and psoriatic arthritis, but they work differently and may be better suited to different people. Guselkumab targets IL-23, while adalimumab blocks TNF-alpha, both important inflammatory proteins.

Clinical studies suggest that guselkumab may be more effective for skin psoriasis, with some people achieving clearer skin compared to adalimumab. However, adalimumab has been available longer and has more extensive data on long-term safety and effectiveness.

The dosing schedules differ significantly. Guselkumab is given every 8 weeks after the initial doses, while adalimumab is typically given every other week. Some people prefer the less frequent dosing of guselkumab.

Your doctor will consider your specific condition, other health problems, previous treatments, and personal preferences when deciding which medication might work better for you. What works best can vary significantly from person to person.