Biologics are disease-modifying antirheumatic drugs (DMARDs) that help slow joint, tendon, and skin damage caused by psoriatic arthritis (PsA). Although biologics are effective for this chronic (long-term) inflammatory condition, some people may notice weight gain after starting treatment.

Research shows that certain biologics may be more likely than others to cause weight gain. Not everyone will experience this side effect, but it’s helpful to know it’s a possibility. If you experience unwanted weight gain after starting a biologic, talk to your doctor. They may suggest changes to your routine or switch your medication to one that’s less likely to affect your weight.

Which Biologics Cause Weight Gain in Psoriatic Arthritis?

MyPsoriasisTeam members have asked others about their experiences with biologics and weight gain. One member said, “I’ve been taking Cosentyx for eight months. After working hard for over a year to lose 60 pounds, I have regained 20 since starting Cosentyx. Do all of the medications have weight gain side effects?”

Some study findings link tumor necrosis factor-alpha (TNF-alpha) inhibitors and interleukin (IL)-12 and IL-23 inhibitors — two classes of biologics — with weight gain. However, doctors and researchers are still learning how different types of biologics may affect weight.

TNF-Alpha Inhibitors

People with PsA have inflammation that’s driven by proteins like TNF-alpha. TNF-alpha inhibitors block this protein to help reduce joint pain, swelling, and skin symptoms.

The U.S. Food and Drug Administration (FDA) has approved five anti-TNF biologics to treat PsA:

• Adalimumab (Humira)
• Certolizumab pegol (Cimzia)
• Etanercept (Enbrel)
• Golimumab (Simponi)
• Infliximab (Remicade)

Some MyPsoriasisTeam members have noticed that they gained a few pounds after starting this type of medication. One member shared, “I’ve been on the Humira injections for about six weeks now. I’m also gaining weight. Has anyone else experienced this?”

A review of 26 studies found that people using these medications gained a small amount of weight — typically, just a few pounds, depending on the drug. For example, people taking adalimumab gained 5 pounds, on average, while those who took infliximab or etanercept gained an average of 2 pounds or 5.2 pounds, respectively. Another study showed that people with PsA gained about 3.4 pounds in the first year of treatment with TNF-alpha blockers.

Interleukin Inhibitors

Interleukin inhibitors block proteins like IL-17 and IL-23 that also cause inflammation in PsA. Your doctor may prescribe these biologics to help control inflammation and PsA symptoms.

The FDA has approved these interleukin inhibitors for PsA:

• Bimekizumab (Bimzelx) — Blocks IL-17A and IL-17F
• Guselkumab (Tremfya) — Blocks IL-23
• Ixekizumab (Taltz) — Blocks IL-17A
• Risankizumab (Skyrizi) — Blocks IL-23
• Secukinumab (Cosentyx) — Blocks IL-17A
• Ustekinumab (Stelara) — Blocks IL-12 and IL-23

Some MyPsoriasisTeam members taking interleukin inhibitors have shared concerns about weight gain. One member asked, “Has anyone else gained weight on Cosentyx? I know the literature says it’s not a side effect, but it sure seems to be!”

Recent research suggests that IL-12/23 inhibitors like ustekinumab may be linked to weight gain. There’s also some evidence that other IL inhibitors, such as IL-17 blockers, could lead to modest weight gain, but findings are limited and not yet conclusive.

One small study found that people who took ustekinumab gained an average of 4.8 pounds over 28 weeks. In a larger study, people using secukinumab (an IL-17A inhibitor) gained an average of 2.2 pounds over six months. Although these studies focused on people with psoriasis, more research is needed to understand how IL inhibitors affect weight in people with psoriatic arthritis.

Selective Costimulation Modulators

A biologic called abatacept (Orencia) works by blocking the overactivation of T cells — immune cells that normally help fight infections but also cause inflammation in PsA. T cells become activated when they interact with other immune cells called antigen-presenting cells (APCs). Abatacept is known as a selective costimulation modulator because it stops T cells from getting activation signals from APCs, which helps reduce inflammation.

So far, studies haven’t linked abatacept to weight gain. In fact, nausea — which could lead to weight loss — is a more common side effect. If you notice weight changes after starting abatacept, consider speaking with your doctor.

Other Causes of Weight Change in Psoriatic Arthritis

People with PsA may notice weight changes for reasons other than side effects of biologics. For example, having a high body weight or obesity (a medical condition defined as having a body mass index, or BMI, above 30) — which is common in PsA — can raise the risk of other health issues and make some biologics and other DMARDs less effective.

Some nonbiologic PsA medications, such as corticosteroids, can also lead to weight gain. These drugs may increase your appetite and make your body hold on to more water, leading to added weight.

PsA itself can contribute to weight changes too. Inflammation, joint pain, swelling, and fatigue can make it harder to stay active. Over time, less movement — combined with challenges around eating well — can lead to weight gain.

Weight Loss in PsA

Weight loss can also happen with PsA. During a flare, you might feel too nauseated or tired to eat, cook, or even shop for food. Severe joint pain can make everyday tasks more difficult, including preparing meals.

Many medications affect the immune system and may increase your risk of infections. Symptoms such as abdominal pain, vomiting, and diarrhea can cause unintentional weight loss. If you develop these symptoms, be sure to talk with your doctor.

Certain PsA medications may also cause weight loss as a side effect. One study found that people taking apremilast (Otezla) lost an average of 4.8 pounds over six months of treatment.

Maintaining or Losing Weight While on Biologics

If you’ve gained unwanted weight after starting a biologic, talk with your doctor about how to maintain or lose weight in a way that works for you. They can offer personalized advice and support. While reducing your weight may help ease some PsA symptoms, it’s not a guaranteed solution for everyone.

Practicing healthy habits can support your overall well-being and may help with weight management. Everyone’s nutritional and fitness needs are different, so it’s best to check with a healthcare professional before making significant changes to your diet or exercise routine.

Eat Well

People with PsA are more likely to live with overweight or obesity, which increases the risk of type 2 diabetes. This condition happens when your body has trouble using insulin to manage blood sugar, which is known as insulin resistance.

A healthy diet may help reduce inflammation, which may ease PsA symptoms. The Arthritis Foundation recommends focusing on whole foods like vegetables and lean proteins (such as legumes and fish) and limiting processed foods and saturated fats. If you need help following a healthy diet, your doctor can refer you to a registered dietitian who can help you build an eating plan that works with your lifestyle and preferences.

Increase Your Physical Activity

Exercise is an important part of weight management and overall health. The American College of Rheumatology recommends physical activity for people living with PsA. Low-impact exercises such as swimming, yoga, and tai chi are gentle on joints, making it easier to stay active. These activities may also help improve flexibility, reduce stiffness, and support joint mobility. What’s most important is that you move in ways that feel safe and enjoyable so that you stay active.

Talk With Others Who Understand

On MyPsoriasisTeam, the social network for people with psoriasis and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with psoriasis.

Have you gained weight after starting a biologic? Do you have questions or concerns about biologics and weight gain? Share your experience in the comments below, or start a conversation by posting on your Activities page.