Many health conditions can cause similar symptoms. For example, both Sjögren’s disease and fibromyalgia can lead to pain, fatigue, and brain fog. Because these conditions share several symptoms, people may wonder whether they’re connected.

There are important differences between them. Sjögren’s disease is an autoimmune condition that can damage the body’s tissues, while fibromyalgia does not cause tissue damage. At the same time, the two conditions share several features. They can affect similar groups of people, may be triggered by some of the same factors, and are often managed in comparable ways.

Because of these overlaps, it can sometimes be difficult to tell Sjögren’s disease and fibromyalgia apart. This similarity may make diagnosis and treatment more challenging.

Below, we’ll take a closer look at Sjögren’s disease and fibromyalgia and explore five ways these conditions are connected.

What Is Sjögren’s Disease?

Sjögren’s disease — previously called Sjögren’s syndrome — is classified as an autoimmune disease. The main purpose of the immune system is to fight off germs and other invaders that are trying to make you sick or otherwise harm you. In other words, your immune system is in charge of keeping you healthy. Autoimmune disorders happen when the immune system mistakenly attacks healthy cells and tissues.

Sjögren’s is most known for causing symptoms like dry eyes and dry mouth. These symptoms happen because the immune system attacks moisture-producing glands in the eyes and mouth — the tear ducts and salivary glands. These attacks lead to inflammation, which damages the glands and prevents them from working as they’re meant to.

Just as Sjögren’s causes chronic dryness in the eyes and mouth, it can also cause the immune system to attack cells and tissues in other parts of the body, like the joints, nerves, and skin.

What Is Fibromyalgia?

Fibromyalgia is a chronic (ongoing) condition that causes pain throughout the body. It can affect muscles and soft tissues in the neck, torso, arms, and legs. Fibromyalgia pain may be more intense at the beginning and end of the day or may stay constant throughout the day.

Researchers don’t yet know exactly what causes fibromyalgia. One popular theory among researchers is, it develops due to changes in the central nervous system (CNS), or the brain and spinal cord. These changes are thought to involve higher-than-normal levels of chemicals in the brain. Specifically, chemicals that signal pain. Meanwhile, the parts of the brain that receive these pain signals appear to form memories of this pain. This can lead to the brain overreacting to different types of signals, both painful and not painful.

Some researchers think the cause of fibromyalgia may have to do with dysfunction in the immune system, the endocrine (hormone) system, or biochemical processes. Certain genes passed down through families may also play a role in fibromyalgia.

How Sjögren’s and Fibromyalgia Are Connected

Although they’re distinct conditions, Sjögren’s and fibromyalgia often have some of the same symptoms, like fatigue and pain. The two conditions also have several other things in common.

1. They Cause Many of the Same Symptoms

Sjögren’s disease is best known for causing what doctors refer to as sicca symptoms — or, chronic dry eyes and dry mouth. Although these are the symptoms most often associated with Sjögren’s, the autoimmune disease often causes other symptoms as well.

Another common symptom of the condition is joint pain. Sjögren’s can cause pain, swelling, or tenderness in multiple joints at once. This usually affects the ankles, wrists, and fingers, but, in some people, may also affect the knees, hips, or shoulders. Sjögren’s may also cause symptoms like chronic fatigue, skin dryness, sleep disturbances, and brain fog.

Fibromyalgia is known for causing widespread pain, or pain that affects the left and right sides of the body as well as body parts above and below the waist. This pain doesn't necessarily happen in the joints. Fibromyalgia causes chronic pain that occurs for three months or longer. The pain is commonly described as aching or dull, and it feels stronger when pressing on certain parts of the body with your finger.

Another common symptom, chronic fatigue, is often caused by trouble sleeping due to pain or other sleeping disorders like sleep apnea. Brain fog is so common among people with fibromyalgia that it’s been nicknamed “fibro fog.”

All of these symptoms can make it challenging to get through the day and negatively impact quality of life. In addition, overlapping symptoms can make it hard for doctors to tell the conditions apart from each other.

2. Sjögren’s and Fibromyalgia Often Occur Together

Sjögren’s often affects people who have, or go on to develop, other autoimmune diseases. When this happens, the conditions are referred to as overlapping diseases. Other health conditions that commonly occur in people with Sjögren’s that aren’t autoimmune are called associated conditions. These conditions often coexist, but one doesn’t cause the other.

Fibromyalgia is noted to be a common associated condition of Sjögren’s. People with Sjögren’s are more likely to get a fibromyalgia diagnosis than the general population. Some research suggests Sjögren’s and fibromyalgia can show up in the same person. But having fibromyalgia does not mean you will definitely develop Sjögren’s. Sjögren’s is most often diagnosed in adults over age 40, though it can happen at other ages. Research has also shown fibromyalgia to be more common in people with other autoimmune diseases, such as rheumatoid arthritis.

When Sjögren’s and fibromyalgia occur together, it can be hard to tell which condition is causing symptoms. For example, people with both conditions may have joint pain due to fibromyalgia rather than Sjögren’s. This can happen because muscle-based fibromyalgia pain may feel as though it comes from the joints. Diagnosis is often complicated by the symptom overlap of these common comorbidities (coexisting conditions).

3. Both Conditions Can Impact the Nervous System

In Sjögren’s, the immune system most often targets the healthy cells and tissues of the eyes and mouth. But the condition may also cause the immune system to attack other parts of the body, such as the nerves. When nerves become inflamed, it can affect their ability to send messages to the brain like those related to pain and sensation, which can increase sensitivity to pain.

Nerve inflammation or damage — called neuropathy — can cause symptoms like numbness, coldness, pain that feels like burning, tingling or stabbing, and weakness. Nerve problems can happen in Sjögren’s. Different studies report different numbers, so the risk can vary a lot. Some people never have nerve symptoms, while others do.

Fibromyalgia is thought to change the way that painful and nonpainful signals are processed by the brain. This change in how the CNS functions makes the body more sensitive to pain and is believed to be due to high levels of pain-signaling chemicals in the brain.

4. They Share Potential Causes and Triggers

Researchers don’t yet know the exact causes of Sjögren’s or fibromyalgia. But evidence suggests that certain risk factors are likely linked to both conditions.

People are more likely to develop Sjögren’s if they get a specific gene passed down to them by a parent. Inheriting certain genes can also raise the risk of developing fibromyalgia. In addition, both conditions may develop in the presence of an overactive immune system and an illness or injury.

Flare-ups — periods when symptoms worsen — may also be triggered by some of the same factors, such as:

• Poor sleep
• Physical or emotional stress
• Weather changes
• Overexertion

5. Treatment Strategies May Overlap

Managing coexisting chronic conditions that share many symptoms can be tricky. Having both Sjögren’s and fibromyalgia may make shared symptoms like pain and fatigue more severe or cause them to happen more frequently.

Since there’s no cure for either condition, treatments are used to manage symptoms with the goal of improving quality of life. Treatment of both conditions focuses on reducing pain and limiting the amount of stress placed on the body to prevent flare-ups.

Treatment strategies for both Sjögren’s and fibromyalgia may include:

• Medications to relieve pain
• Self-care strategies to reduce stress and promote relaxation, such as breathing exercises, and mindfulness practices, like meditation
• Sleep hygiene practices to improve sleep, such as keeping bedtimes consistent and making sure your bedroom is dark with a comfortable temperature and humidity level
• Regular exercise to help reduce pain over time
• Paced physical activities to prevent overexertion
• A healthy diet and limiting of caffeine intake to reduce brain fog and sleep disruptions

If you have, or are suspected of having, both Sjögren’s and fibromyalgia, your doctor may refer you to a rheumatology provider for care. A rheumatologist is a doctor who specializes in diagnosing and treating rheumatic diseases — or conditions that involve inflammation, the immune system, and progressive joint and muscle issues. These healthcare providers are often better able to identify and treat commonly overlapping diseases like Sjögren’s and fibromyalgia.

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On MySjögrensTeam, people share their experiences with Sjögren’s, get advice, and find support from others who understand.

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