9 Diseases That Can Mimic Fibromyalgia (and Delay Your Diagnosis)

Fibromyalgia can be tricky to diagnose, which is why you may have one of these other conditions instead.

While no one knows what exactly causes fibromyalgia, doctors do know a few things about the condition: The widespread chronic pain disorder seems to involve the nervous system; affects 2 to 4 percent of Americans, mostly women; and commonly occurs in people who have other types of musculoskeletal pain, such as different kinds of arthritis.

But unlike many musculoskeletal conditions, fibromyalgia isn’t an inflammatory or autoimmune disease — when your immune system, which normally protects your body from infection, turns against itself and attacks your own cells and tissues. That can produce chronic inflammation that can eventually damage your body. Fibromyalgia is also not a joint or muscle disorder caused by physical injury.

Instead, experts think that fibromyalgia is neurological in nature.

“Fibromyalgia is a disorder in which the sensitivity to pain has been turned up in the brain,” says J. Michelle Kahlenberg, MD, PhD, an associate professor in the division of rheumatology at the University of Michigan Medical School in Ann Arbor. “Chemical transmitters in the brain have gotten reprogrammed so that they are firing pain signals with very minimal stimuli. A squeeze of the arm, a shake of the hand, a touch on the shoulder — all of those things can be very painful for people with fibromyalgia.”

pain in their joints as well as fatigue, memory issues, and headaches and stomachaches. But unlike fibro, lupus is an autoimmune disorder that causes widespread inflammation throughout the organs, especially the kidneys, lung tissue, heart, and brain.

Other physical symptoms of lupus can be very different too: “[Lupus can cause] skin rashes, hair falling out — not just a little bit of hair in the drain, but bald spots on the head,” notes Dr. Kahlenberg. There is also recurring pericarditis, which is chest pain brought about by inflammation of the tissue surrounding the heart, and kidney damage.

To rule out lupus, primary care providers usually order a blood test called an ANA test that measures certain autoantibodies in your body (a sign that your immune system is attacking normal cells instead of harmful bacteria or viruses). But a positive ANA doesn’t necessarily mean you have lupus. “A lot of people have a positive ANA for many reasons, most of which have to do with being exposed to some virus that had a little bit of overlap with their body’s tissues,” says Dr. Kahlenberg.

Of course, patients with lupus can also have fibromyalgia, which is why Dr. Kahlenberg also gives them the Michigan Body Map test, which allows patients to pinpoint the locations on their bodies where they feel pain. “If patients score high enough on a widespread pain index, then that would be diagnostic of fibromyalgia,” she says.

But whether you have fibro along with lupus or just lupus alone, it’s important to get the right treatment so the lupus doesn’t progress and cause more organ damage, which can be life-threatening. So you’ll want to talk to your provider about a combination of medications (usually steroids and anti-malarial drugs) that can suppress your immune system.

factors and anti-CCPs, among other inflammatory markers. You may also have X-rays that show any damage to the joints (though this “radiographic damage” may not show up in the early stages of RA).

Left untreated, rheumatoid arthritis can deform the joints in your hands and feet and elsewhere and increase your risk for heart problems and lung disease. Luckily, treatments exist for even serious cases. Many patients take disease-modifying antirheumatic drugs, including biologics, along with low-dose steroids or pain relievers and find relief from the pain and swelling.

But there are differences between them. People with chronic fatigue have enlarged lymph nodes and sometimes a sore throat. And most importantly, the fatigue is more overpowering than the pain (the reverse is true in fibromyalgia).

Doctors aren’t exactly sure what causes chronic fatigue syndrome, though some think its origins could be viral — from the flu, say, or the virus that causes mononucleosis. But your provider will arrive at a diagnosis of CFS in a similar way to that of fibromyalgia, by excluding other conditions through careful sleuthing and tests.

Treatment can be tricky too. Sometimes even the gentlest workouts can make CFS symptoms worse (while they can be beneficial for patients with fibro, especially meditative exercise like tai chi, says Dr. Kahlenberg). Cognitive behavior therapy can help manage chronic pain, as can antidepressants, since CFS patients also have depression (understandably).

Getting to the Bottom of Fibromyalgia — or a Different Diagnosis

So how can you be sure you really have fibromyalgia? First, be sure your provider runs labs, gets a thorough medical history, including sleep (to rule out sleep apnea), and does a top-to-toe physical exam, says Dr. Morris. “We examine and look at the muscles and the joints and see if and where they’re tender. Do they have good range of motion? Do they have good muscle strength? Those are some of the things that we look for,” he explains.

Then your provider should ask questions like these: Is your pain and fatigue concentrated in the muscles or the joints? Does your pain get better or worse with activity?

While you don’t have to meet the tender points criteria, a doctor will probably follow these general guidelines to see whether you could have fibromyalgia.

You too should ask questions, says Dr. Kahlenberg: “‘Is there any evidence of inflammation?’ ‘Do I have evidence of any other autoimmune disease?’ ‘Could there be any other reason for my pain?’ I think an honest conversation with the doctor to say, ‘Why do you think this versus this,’ is a reasonable thing. If you don’t get answers that are helpful, then seek a second opinion at that point.”