How do doctors tell if it's fibromyalgia or another condition?​

So how do doctors differentiate fibromyalgia from other conditions since fibromyalgia shares symptoms with many other conditions like chronic fatigue syndrome, rheumatoid arthritis, and lupus. 

Here's how doctors usually differentiate fibromyalgia from other diagnoses:​

🩺 1. Patient History & Symptoms

Doctors start by listening to your story:

• Widespread pain (on both sides of the body, above and below the waist)

• Fatigue

• Sleep disturbances

• Cognitive issues ("fibro fog")

• Sensitivity to touch (allodynia), light, sound, or temperature

They’ll also ask:

• How long symptoms have lasted (typically 3+ months)

• If symptoms are persistent or come and go

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✅ 2. American College of Rheumatology (ACR) Criteria

Instead of the old "tender point" test, doctors now often use these criteria:

• Widespread Pain Index (WPI): Scores how many areas of the body hurt

• Symptom Severity Scale (SSS): Assesses fatigue, cognitive symptoms, and unrefreshing sleep

• A diagnosis is supported if the WPI and SSS scores meet a certain threshold, without another disorder explaining the symptoms.

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🧪 3. Rule Out Other Conditions

There’s no lab test for fibromyalgia, so doctors order blood work to rule out other possible causes, such as:

• Thyroid disorders

• Vitamin deficiencies (like B12 or D)

• Autoimmune diseases (e.g. lupus, rheumatoid arthritis)

• Anemia

• Infections

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🤯 4. No Inflammation or Tissue Damage

Fibromyalgia pain doesn’t come from inflammation or joint damage (unlike arthritis or lupus), and imaging usually shows no structural problems. If a patient has pain but normal blood tests and imaging, it supports a fibro diagnosis.

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🧬 5. Central Sensitization

Doctors consider whether pain may be amplified by the central nervous system. Fibromyalgia is a central sensitivity syndrome, meaning the brain and nerves are overly reactive to sensory input.

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💡 Bonus: Common Mistaken Diagnoses

Sometimes fibromyalgia is confused with:

• Chronic Fatigue Syndrome (CFS/ME)

• Lyme disease

• Depression or anxiety disorders

• Myofascial pain syndrome

• Multiple sclerosis (MS)

So careful differential diagnosis is key.

I hope this clears up some of the questions you have about why fibromyalgia is diagnosed and not another condition. Of course you can have Fibromyalgia and other diseases as well. 😕 I personally have autoimmune conditions and osteoarthritis as well as Fibro. 

You may also find the following articles interesting:

• How can a doctor diagnose Fibromyalgia which includes why you may find it difficult to get a diagnosis. 
• 14 reasons it may NOT be Fibromyalgia
• 2010 set of criteria for diagnosing Fibromyalgia.