Studies have reported cases of people developing autoimmune diseases like rheumatoid arthritis and lupus after undergoing gastric bypass surgery. But research is mixed as to whether there’s a link.

Roux-en-Y gastric bypass, better known as gastric bypass surgery, involves stapling your stomach, dividing the small intestine to create a smaller pouch, and then reconnecting the upper portion of your small intestine to a different location.

Doctors typically consider it for adults who have:

  • a body mass index (BMI) over 35
  • type 2 diabetes and a BMI over 30
  • a BMI between 30 and 35, but other weight loss strategies have failed

Like other major surgeries, gastric bypass may carry the risk of complications. One possibility is the development of autoimmune disorders, although more research is needed to confirm.

Read on to learn more about what the science says, as well as possible symptoms of autoimmune disorders and other possible gastric bypass complications you need to be aware of.

The goal of gastric bypass surgery is to help people lose weight by creating feelings of fullness for longer, as well as helping food “bypass” most of the stomach in an attempt to decrease overall calorie intake.

Still, gastric bypass is a major procedure. Like other common types of bariatric surgery, it’s not a first-line treatment. Doctors only recommend it when other therapies do not work. Part of the reason for the selective nature is the risk of complications.

Some research reports that autoimmune disorders may be one such potential complication.

Autoimmune disorders develop when your immune system overreacts. This causes proteins called autoantibodies to mistakenly attack healthy cells and tissues in your body, as well as inflammation.

One such study from 2019 described these immunological changes in people who underwent bariatric surgery.

The researchers documented previous cases in which people developed rheumatoid arthritis (RA) and lupus, two different types of autoimmune disorders, after bariatric surgery. They believed there might be a connection between weight loss surgery and changes in both T-lymphocytes and autoantibodies.

Conflicting reports

However, unlike other well-established complications, research linking gastric bypass surgery with autoimmune disease development is mixed.

For example, a 2023 preliminary report pointed to obesity as a risk factor for autoimmune disease development and not the bariatric surgeries doctors use to treat obesity.

Researchers in this study found that most of the 79 people studied had lower levels of autoimmune disease-related antibodies after weight loss from their surgeries.

Separately, a 2020 study on two groups of people with RA over 12 months found that the bariatric surgery group experienced less disease activity than the nonsurgery group.

While there’s no clear relationship between gastric bypass surgery and autoimmune diseases, more research is needed to investigate why some people develop higher levels of autoantibodies after weight loss surgeries.

In the meantime, it’s important to be aware of the possible symptoms of autoimmune disorders. Some of the most common symptoms of these conditions include:

  • pain
  • skin discoloration
  • skin rashes
  • swelling
  • heat
  • fatigue
  • fever

Scientists have identified at least 80 different autoimmune diseases, with the exact symptoms varying based on each disorder and affected part of the body.

For example, RA and lupus can both cause inflammation and pain in your joints. Lupus can be more systemic, leading to symptoms that affect your skin, heart, and other areas of the body.

Autoimmune disorders also tend to cause cycles of symptom flare-ups and remission. Treatment and management strategies may be lifelong once you develop an autoimmune condition.

When to contact a doctor

If you’re experiencing ongoing fatigue, pain, or swelling after recently having gastric bypass surgery, consider contacting a doctor. They can help determine the underlying cause of your symptoms with a physical exam, blood test, and possible imaging tests.

Before undergoing any type of bariatric surgery, it’s important to discuss all the possible benefits versus risks with your doctor.

Possible complications include:

What is the most common complication of gastric bypass surgery?

Gallstones are among the most common chronic complications of gastric bypass surgery. These tend to form within 6 months after you have the procedure.

Anastomotic stricture is another common complication with this surgery. It occurs when scar tissue at the site of surgical connection (anastomosis) causes the passageway to narrow, blocking food from moving through your digestive system.

It develops in 3% to 7% of laparoscopic (minimally invasive) gastric bypass surgeries.

Does a gastric bypass affect your immune system?

While major surgeries like gastric bypass can affect your immune system and increase your risk for infections, research is mixed about how the surgery might alter your immune system in the long term and cause autoimmune disorders.

Can a gastric bypass cause problems years later?

Most people who have a gastric bypass require hospitalization or follow-up surgery within 5 years of the initial surgery. There’s also a small chance a surgeon can reverse this procedure if medically necessary.

What is the root cause of most autoimmune diseases?

The exact causes of most autoimmune diseases aren’t known. In many cases, experts think that some people may have a genetic predisposition to them. Environmental factors, such as infections or exposure to chemicals, may then trigger them.

Reports exist of some people developing autoimmune disorders after recently undergoing bariatric surgeries like gastric bypass.

However, it’s not yet clear whether there’s a clear link between the two. Some researchers think previous obesity may be a more likely risk factor.

While more research is needed to understand the possible links between gastric bypass surgery and autoimmune disorders, consider talking with a doctor if you experience any unusual symptoms after your weight loss procedure or if you have any concerns before having surgery.