13 Conditions That Mimic Fibromyalgia

Do you think you might have fibromyalgia? The symptoms may be due to some other condition.

Think you might have fibromyalgia? It can be surprisingly hard to tell, even for your physician. There are no blood tests or scans that offer an easy answer.

As a result, the first step toward a fibromyalgia diagnosis is ruling out all other possibilities.

Here are some common conditions that your doctor may consider when trying to figure out if your pain (or other symptom) is caused by fibromyalgia, something else, or possibly both.



The most common form of arthritis is called osteoarthritis, and it is characterized by cartilage degeneration that can lead to tissue and bone damage and terrible joint pain.

This type of pain can mimic the pain in fibromyalgia tender points, such as the hips and knees.

What's more, both osteoarthritis and fibromyalgia can cause morning stiffness.

Chronic Fatigue Syndrome

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Another hard-to-diagnose condition is chronic fatigue syndrome (CFS).

CFS has no known cause, but is characterized by fatigue so severe it derails the whole day. Even after getting adequate sleep and rest, someone with CFS may not have any energy

The fatigue can be accompanied by memory problems, headaches, and pain in the muscles and joints, which are all symptoms of fibromyalgia as well.

"At least 50 percent of people with fibromyalgia meet criteria for CFS," says Daniel Clauw, MD, the Director of the Chronic Pain and Fatigue Research Center at the University of Michigan. "That can be confusing to patients."


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Fibromyalgia can often trigger depression; after all, living with everyday pain can be challenging and sometimes demoralizing. However, the symptoms of the two conditions often overlap as well.

Depression, which includes profound feelings of sadness, hopelessness, and loss of interest in activities, can cause a person to think or speak slower than usual or have memory and concentration problems—as can fibromyalgia.



Hypothyroidism—an underproduction of hormones by the thyroid gland in the neck—is caused by an abnormal immune system response that mistakenly attacks normal body tissue.

In this case, the immune response causes a drop in thyroid hormone, a key player in how the body uses energy.

"Having low levels of this hormone can cause people to 'hurt all over'," says Dr. Clauw.

The condition is also linked to a slew of other symptoms that overlap with fibromyalgia, such as fatigue, depression, memory loss, and constipation.

"We generally recommend to check thyroid function before diagnosing someone with fibromyalgia," says Dr. Clauw.

Irritable Bowel Syndrome


Fibromyalgia symptoms like alternating bouts of constipation or diarrhea may be caused by irritable bowel syndrome (IBS), a digestive problem that has no known cause but can be exacerbated by stress or eating certain foods.

Medications may help reduce IBS symptoms, which can also include cramps and stomach pain.

The good news is that IBS does not seem to increase the risk of cancer like some types of inflammatory bowel disease, an ailment that can cause ulcers and inflammation in the digestive tract.

Jaw Problems

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Temporomandibular disorder is an ailment in which jaw problems result from nighttime teeth grinding or clenching.

Chewing, yawning, or talking can be painful, and headaches are common—all of which may be confused for fibromyalgia pain.



The immune system of a person with lupus will attack normal body tissues, causing inflammation and pain through the muscles and joints, much like the pain experienced by people with fibromyalgia.

People with both conditions are likely to see their symptoms come and go in flares, and they may also experience fatigue. However, lupus patients are likely to have a fever or skin rash (such as a butterfly-shaped rash across the nose and cheeks) along with their fibromyalgia-like symptoms.

Lyme Disease


Some people diagnosed with fibromyalgia report having had Lyme disease in the past. While there's no research yet to prove a direct connection between the two conditions, "there are a number of infections [including Lyme disease] that seem to be capable of triggering fibromyalgia," says Dr. Clauw.

The fatigue, headaches, muscle and joint pain, and stiffness characteristic of Lyme disease are caused by bacteria spread via the bite of an infected deer tick, but blood tests for Lyme disease aren't always reliable. Diagnosing Lyme disease can therefore be difficult, as the symptoms overlap with fibromyalgia and a slew of other conditions.

Lyme disease can be treated with antibiotics.

Interstitial Cystitis


Interstitial cystitis, sometimes called painful bladder syndrome, inflammation of the bladder wall is likely to feel like a urinary tract infection.

Similarly misunderstood, fibromyalgia and interstitial cystitis both seem to originate in the nerves and produce chronic pain.

The two conditions often occur together and are both more common in women.

Polymyalgia Rheumatica

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"Fibromyalgia is probably most likely to be confused for this inflammatory disorder in people over 50," says Dr. Clauw. Its characteristic pain and stiffness in the hips, neck, and shoulders are all common in fibromyalgia patients too.

Polymyalgia rheumatica is most common in people older than 50 and may also cause morning stiffness and headaches—both common in people with fibromyalgia.

Restless Legs Syndrome

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Characterized by uncomfortable pins-and-needles sensations in the legs and the irresistible urge to move the legs, the cause of restless legs syndrome (RLS) remains mostly a mystery.

Moving the legs seems to temporarily alleviate the intense feelings, but people with RLS tend to get poor sleep in general and to experience severe fatigue like that felt by many people with fibromyalgia.

Rheumatoid Arthritis

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The painful, swollen, and stiff joints characteristic of rheumatoid arthritis (RA) are also common complaints for people with fibromyalgia. Unlike the more common osteoarthritis, which is caused by age-related wear and tear, rheumatoid arthritis can occur at any age and is caused by inflammation and destruction of the lining of the joints.

RA can strike in the same joints on both sides of the body, similar to the symmetrical tender points used to diagnose fibromyalgia, and can cause fatigue and morning stiffness.

Sleep Apnea

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Many fibromyalgia patients have trouble sleeping. The catch-22 is that sleeping better could actually improve their symptoms.

In some instances, the fibro pain itself could be interfering with sleep. But an underlying disorder like sleep apnea may, in fact, be the problem keeping you up at night.

A person with sleep apnea tends to snore and stop breathing for several seconds or more while asleep, then snorts and gasps for breath. This results in fitful sleep and feeling tired upon waking.

Treating the sleep disorder should lead to better z's, even if fibro symptoms persist.

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