Disclaimer: Human Health is a health-tracking platform and does not provide medical advice, diagnosis, or treatment. The information in this article is for educational purposes only and is not a substitute for professional medical advice. Always talk to your doctor or another qualified healthcare provider about your specific situation.

If you live with fibromyalgia, you know how unpredictable the pain and fatigue can be. When muscle spasms appear as sudden twitches, tight knots, or cramping, they add another layer of discomfort that can interrupt sleep, movement, and daily life.

Fibromyalgia changes how the nervous system processes signals, which can make ordinary muscle tension feel sharper or longer-lasting. 

This guide explains what’s known about fibromyalgia muscle spasms, their common causes and symptoms, ways to ease them at home, and when to seek medical help. It also shows how the Human Health app can help you track spasms, identify triggers, and share clear records with your healthcare provider.

Are muscle spasms part of fibromyalgia common symptoms?

Muscle spasms are not on the official fibromyalgia checklist, but some people with the condition report experiencing them. A spasm is an involuntary tightening of a muscle that may feel like a knot. A cramp is a stronger, longer spasm that often feels like a sharp squeeze, while a twitch is a quick flutter under the skin. These differ from neurological spasticity, which comes from brain or spinal cord injury. In fibromyalgia, the nervous system amplifies normal muscle signals, so mild tension may feel like stiffness to some, or like painful cramps and spasms to others.

Possible reasons fibromyalgia may cause muscle spasms

Muscle spasms linked to fibromyalgia usually do not come from a single cause. Instead, several overlapping factors can make muscles more sensitive and prone to tightening.

1. Fibromyalgia flare-ups

During a fibromyalgia flare-up, the nervous system can become more reactive to pain and stress. This may cause muscles to tighten suddenly, leading to spasms or cramps that feel stronger than usual.

Did You Know?

Research shows that intramuscular pressure in people with fibromyalgia is almost three times higher than in those without the condition. This may help explain why cramps and spasms are more common, especially in the legs and feet.

2. Stress and poor sleep

High stress levels and disrupted deep sleep are common in fibromyalgia. Both may interfere with normal nerve signaling and may make muscles more likely to twitch or stiffen, particularly at night.

3. Overuse or inactivity

Muscle tissue in fibromyalgia may be more reactive. New or unusual activities (e.g., gardening, stair climbing) or prolonged stillness may stress muscles and increase the chance of spasms or stiffness.

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Where do muscle spasms occur?

Muscle spasms in fibromyalgia may affect many areas, but they tend to occur more often in regions of postural strain or frequent use (e.g., neck, shoulders, back).

1. Neck and shoulder tightness

Neck and shoulder muscles commonly bear stress and postural burden, making them frequent sites for spasms or tender knots in fibromyalgia sufferers.

2. Upper back and hips

Upper back and hip regions are also vulnerable, especially after prolonged sitting or awkward sleep postures, and may experience spasms that radiate toward the glutes or thighs.

3. Legs and feet

In fibromyalgia, higher pressure inside muscles may reduce blood flow and oxygen, leading to pain and cramp-like sensations. This can make areas like the calves, hamstrings, or arches of the feet cramp, sometimes at night or after activity

To understand the underlying causes and management strategies, explore our comprehensive article on fibromyalgia foot pain.

4. Arms/forearms

These regions often show up in fibromyalgia pain maps (e.g. the Widespread Pain Index). Because they are actively used in daily tasks (lifting, typing, reaching), they may develop spasms or cramps from chronic strain.

5. Chest and rib Area

Some people with fibromyalgia describe tightness or spasms around the ribs, which may come from the chest wall or intercostal muscles.

Muscle spasms in fibromyalgia may appear in many areas, but noticing when and where they arise can give you and your healthcare provider useful clues for managing them.

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How to manage fibromyalgia-related muscle spasms

Muscle spasms are not formally listed in fibromyalgia criteria, yet patients sometimes report cramps, stiffness, or tightness that resemble spasms. The following approaches are drawn from studies on pain, cramps, and muscle function, and may help ease these symptoms day to day.

1. Apply gentle heat, then stretch

Using gentle heat (such as a warm shower, heating pad, or warm compress) can raise tissue temperature and improve blood flow, which helps muscles relax and become more pliable. After warming, following with slow, gentle stretches may enhance flexibility and reduce tightness. 

2. Stay hydrated and balance electrolytes

Because dehydration and low electrolyte levels (especially after fluid loss) may lower the threshold for muscle cramps, ensuring regular hydration and eating electrolyte-rich foods (such as bananas or leafy greens) may support proper muscle cell function and help resist cramp onset.

3. Take movement breaks

Introducing short, low-impact movement breaks (for example, light walking or gentle shoulder rolls) during long sitting or standing sessions can reduce stiffness and promote circulation.

4. Practice relaxation breathing or light self-massage

Because stress can exacerbate muscle tension and spasms, practices such as deep, slow breathing or gentle self-massage (e.g., with a soft ball) may encourage muscle relaxation, calm the nervous system, and ease discomfort by reducing involuntary muscle tightening.

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When should you see a doctor?

Occasional mild spasms may be managed at home, but it’s important to reach out to a healthcare professional if you notice any of the following:

• Spasms that are frequent, severe, or worsening over time
• Muscle cramps that interfere with sleep, mobility, or daily activities
• Swelling, redness, or sudden weakness in the affected area
• Spasms that come with numbness, tingling, or a new kind of pain

A clinician can help rule out other conditions and discuss treatment options tailored to you.

Use the Human Health app to track fibromyalgia and muscle spasms symptoms & flares

Living with fibromyalgia can feel unpredictable, but tracking your symptoms gives you and your care team clearer insights. With the Human Health app, you can:

• Log spasms and flares daily to track their progression over time.
• Add notes on activity, sleep, stress, or weather to uncover personal triggers.
• Export shareable PDF summaries so your provider sees the full picture at a glance.

By bringing your records together in one secure place, you save time, reduce uncertainty, and feel more prepared for every appointment.‍

Start today by tracking your next flare. Small steps can build a clearer path forward.

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Disclaimer: Human Health is a health-tracking platform and does not provide medical advice, diagnosis, or treatment. The information on this site is intended to support, not replace, conversations with qualified healthcare professionals.

References

• National Library of Medicine: Spasticity
• National Library of Medicine: The Science of Fibromyalgia
• BMC: Fibromyalgia, myofascial pain, tender points and trigger points: splitting or lumping?
• National Library of Medicine: Neurobiology of fibromyalgia and chronic widespread pain
• National Library of Medicine: Psychological stress and fibromyalgia: a review of the evidence suggesting a neuroendocrine link
• LIDSEN Publishing Inc.: Sleep Dysfunction in Fibromyalgia and Therapeutic Approach Options
• National Library of Medicine: Fibromyalgia: Pathogenesis, Mechanisms, Diagnosis and Treatment Options Update
• National Library of Medicine: Fibromyalgia Syndrome: An Overview of Pathophysiology, Diagnosis and Management
• The Journal of Rheumatology: Intramuscular Pressure Is Almost Three Times Higher in Fibromyalgia Patients: A Possible Mechanism for Understanding the Muscle Pain and Tenderness
• National Library of Medicine: Fibromyalgia
• National Library of Medicine: Costochondritis
• National Library of Medicine: A Role for Superficial Heat Therapy in the Management of Non-Specific, Mild-to-Moderate Low Back Pain in Current Clinical Practice: A Narrative Review
• National Library of Medicine: Water intake after dehydration makes muscles more susceptible to cramp but electrolytes reverse that effect
• National Library of Medicine: Effect of physical activity breaks during prolonged sitting on vascular outcomes: A scoping review
• National Library of Medicine: Effectiveness of Progressive Muscle Relaxation, Deep Breathing, and Guided Imagery in Promoting Psychological and Physiological States of Relaxation