Fibromyalgia vs. POTS: How to Tell Them Apart When Symptoms Overlap

Fibromyalgia and postural orthostatic tachycardia syndrome (POTS) are two of the most commonly confused chronic conditions, and for good reason — they share a remarkable number of symptoms. Both cause fatigue, cognitive dysfunction (brain fog), widespread pain, sleep disturbances, and exercise intolerance. Both predominantly affect women. Both are frequently dismissed by clinicians. And both can be present simultaneously in the same patient.

Understanding the distinctions between them is important because the treatments differ significantly, and treating one condition as if it were the other can lead to worsening symptoms.

Key Distinguishing Features

The Orthostatic Test: The Key Differentiator

The most reliable way to distinguish POTS from fibromyalgia is the orthostatic heart rate response. In POTS, heart rate increases by ≥30 bpm (≥40 bpm in patients under 19) within 10 minutes of standing, without a significant drop in blood pressure. In fibromyalgia without POTS, heart rate may increase slightly on standing but does not meet the POTS threshold.

The NASA Lean Test (standing against a wall for 10 minutes with heart rate monitoring) can be performed at home and is a reasonable screening tool. A formal tilt table test provides more definitive diagnosis.

Why They Often Co-occur

Fibromyalgia and POTS co-occur at rates of 20–40% — far higher than chance. The reasons for this overlap include:

Shared mechanisms. Both conditions involve dysregulation of the autonomic nervous system and central sensitization. POTS-related cerebral hypoperfusion (reduced blood flow to the brain) activates the same central pain amplification pathways that drive fibromyalgia. Conversely, the chronic pain and stress of fibromyalgia can dysregulate the autonomic nervous system, contributing to POTS.

Shared underlying conditions. Both fibromyalgia and POTS are associated with hEDS/HSD, MCAS, and autoimmune conditions. A patient with hEDS may develop both conditions independently through the same underlying connective tissue and immune mechanisms.

Diagnostic confusion. Patients with POTS who have not been diagnosed may be labeled with fibromyalgia based on their fatigue and pain, particularly if their orthostatic symptoms are not recognized.

Treatment Implications

If you have POTS but not fibromyalgia: Standard POTS management (sodium, fluids, compression, medications) often improves fatigue, brain fog, and even pain significantly. Graded exercise therapy (GET) is appropriate and beneficial.

If you have fibromyalgia but not POTS: Fibromyalgia management (low-impact aerobic exercise, cognitive behavioral therapy, medications like duloxetine or pregabalin, sleep optimization) is appropriate. Orthostatic management is not needed.

If you have both: This is the most complex scenario. POTS management should be prioritized first, as untreated POTS worsens fibromyalgia through cerebral hypoperfusion and autonomic instability. Exercise should be recumbent initially (swimming, rowing, recumbent cycling) to avoid orthostatic triggers, then gradually transitioned to upright exercise as POTS improves.

ChatDys resources: Perform the NASA Lean Test using our guide to screen for POTS. Track your pain, fatigue, and orthostatic symptoms in the Health Tracker. Complete your Health Roadmap for a personalized plan that addresses both conditions.