Biologics are a newer class of medications used to treat psoriatic arthritis (PsA) and other autoimmune diseases. These are disease-modifying antirheumatic drugs (DMARDs) that help slow joint damage and PsA progression. Although biologics are effective, they may come with some side effects, such as unwanted weight gain.

Studies show that some biologics are associated with weight gain more than others. Not everyone will experience these side effects, but it can help to know what to expect when starting a new medication. If you begin to notice unwanted weight gain while taking a biologic, your doctor can offer you tips and lifestyle changes to help. They may also switch your medication to help you avoid unwanted side effects.

Which Biologics Cause Weight Gain in Psoriatic Arthritis?

MyPsoriasisTeam members have asked others about their experiences with biologics and weight gain. One member who takes the biologic Cosentyx (a formulation of secukinumab) shared the following, “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?”

Studies show that tumor necrosis-alpha (TNF-alpha) inhibitors — a class of biologics — are commonly associated with weight gain. However, doctors and researchers are still learning how other types of biologics may cause similar side effects.

TNF-Alpha Inhibitors

People with PsA tend to have more of the protein TNF-alpha in their bodies, which is responsible for causing inflammation. TNF-alpha inhibitors block this protein, helping to treat joint pain, swelling, and skin symptoms in PsA.

The U.S. Food and Drug Administration (FDA) has approved formulations of five anti-TNF biologics for treating PsA:

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

Some MyPsoriasisTeam members have noticed they gained a few pounds using an anti-TNF agent. One member shared, “I’ve been on the Humira injections for about 6 weeks now. I’m also gaining weight. Has anyone else experienced this?”

Research shows that TNF-alpha inhibitors are associated with weight gain, typically just a few pounds. One large analysis of many studies with more than 1,000 people found that the amount of weight gained depends on the medication. People who took adalimumab gained 5 pounds on average, while those who took infliximab or etanercept gained an average of 2 pounds or 5.2 pounds, respectively. (The treatment durations varied among the different studies.)

Another study followed people with PsA or other inflammatory conditions that affect the joints (rheumatoid arthritis and ankylosing spondylitis) who took TNF-alpha inhibitors. Researchers found that 13.3 percent of people experienced weight gain. On average, they gained 12.1 pounds from treatment.

These studies found that weight gain is a possible side effect of TNF-alpha inhibitors. However, these measurements are combined from hundreds to thousands of participants. Your individual experience with PsA and your overall health can affect any weight changes you may have.

Interleukin Inhibitors

Interleukins (ILs) are another type of protein that creates excess inflammation in PsA. Your doctor may prescribe you an IL inhibitor that blocks one or more of these proteins (such as IL-12 or IL-23) to control inflammation and PsA symptoms.

The FDA has approved formulations of four IL inhibitors that block different proteins:

• Ustekinumab (Stelara) — IL-12/IL-23 inhibitor
• Guselkumab (Tremfya) — IL-23 inhibitor
• Secukinumab (Cosentyx) — IL-17 inhibitor
• Ixekizumab (Taltz) — IL-17 inhibitor

Although researchers don’t know as much about how IL inhibitors affect weight, some MyPsoriasisTeam members have experienced weight gain taking them. 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!”

Initial clinical studies for IL inhibitors such as secukinumab didn’t report weight gain as a side effect. Recently, other studies have reported mixed results — some show that these treatments may have no effect, while others show they may even cause weight loss.

One small study of people with psoriasis found that ustekinumab caused an average weight gain of 4.8 pounds over 28 weeks. Another larger study of people with psoriasis taking secukinumab found that the biologic caused an average weight gain of 2.2 pounds over the course of six months.

Doctors and researchers will need to perform more studies to learn how IL inhibitors affect weight in larger groups and in people with PsA.

Selective Costimulation Modulators

T cells are important immune cells that help fight infections. They’re activated by other cells known as antigen-presenting cells (APCs). In PsA, T cells are overactivated, causing too much inflammation and damage. A selective costimulation modulator called abatacept (Orencia) blocks T cells from interacting with APCs, preventing their activation.

There are currently no studies that show abatacept causes weight gain. In fact, during clinical studies, nausea was reported as a common side effect, a symptom that may instead lead to weight loss. If you notice weight gain after starting abatacept, talk to your doctor. There may be something else causing this weight change.

Other Causes of Weight Change in Psoriatic Arthritis

Many people with PsA also experience unwanted weight changes outside of taking certain medications. Being overweight or developing obesity (clinically defined as having a body mass index, or BMI, above 30) is common in those with PsA. Having a higher body weight may put you at risk for other health complications. It can also make some biologics and other DMARDs less effective.

Other PsA medications — like corticosteroids — are known to make you hungrier and cause your body to hold on to more water, leading to weight gain. Your doctor may give you a corticosteroid along with a biologic to make them more effective. These are typically prescribed for a short period of time to avoid other unwanted side effects.

PsA affects the skin as well as the joints. Inflammation, pain, swelling, and fatigue can make it harder to stay active. Over time, a lack of exercise and a poor diet can lead to weight gain.

Weight Loss in PsA

You may also experience weight loss while living with PsA. Many medications interfere with your immune system, which increases your risk of infections. Symptoms of an infection such as abdominal pain, vomiting, or diarrhea can cause weight loss. If you begin to notice any of these signs, talk to your doctor.

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

Managing Weight Gain From Biologics

If you’ve experienced unwanted weight gain after starting a biologic, talk to your doctor about ways to manage it. They can offer you tips and give advice on reaching and maintaining a healthy weight for your body type. Lowering your BMI may also help reduce PsA symptoms, helping you lead a healthier, more comfortable life.

Develop Healthy Habits

You may want to try eating well and adding exercise to your daily routine if you are not currently doing so. It’s important to remember that everyone’s nutritional and fitness needs are different, so it’s best to consult a health care professional before making any significant changes to your diet or exercise regimen.

Eat Well

People with PsA are more likely to experience overweight or obesity, which increases the risk of type 2 diabetes. This condition develops when your body’s cells can’t properly use insulin to burn sugar as fuel (known as insulin resistance).

Following a healthy diet that’s low in sugar, fats, and high-calorie processed foods can help you lose extra weight and reduce your risk of diabetes and other health complications. These changes can also help reduce inflammation, which may lessen PsA symptoms.

If you need help following a healthy diet, your doctor can refer you to a registered dietitian. They’ll help you make an eating plan high in fruits, vegetables, lean meats, and complex carbohydrates.

Increase Your Physical Activity

The American College of Rheumatology recommends exercise for losing weight. For people with active PsA, low-impact exercises like swimming, yoga, and tai chi are best. They put less pressure on your joints, making it easier to stay active. Choose activities that you find enjoyable, and don’t push yourself too hard.

Talk With Others Who Understand

MyPsoriasisTeam is the social network for people with psoriatic arthritis and their loved ones. On MyPsoriasisTeam, more than 114,000 members come together to ask questions, give advice, and share their stories with others who understand life with psoriatic arthritis.

Have you experienced weight gain after starting a biologic? Share your experience in the comments below, or start a conversation by posting on your Activities page.