Causes of Persistent Muscle Pain and Cramps. 

The following table lists a number of recognised causes of usually severe, persistent (i.e. not occasional or transient, but repetitive and ongoing) muscle pain and/or cramps other than CFS and fibromyalgia. They are all rare or uncommon. Do not forget that a common cause of persistent muscle ache and cramps is mineral deficiency and/or dehydration. Minerals that may be deficient include potassium, sodium (as found in common salt), chlorine (as found in common salt), magnesium or calcium. Of course, over-exercise (or unaccustomed exercise) is a common cause of transient muscle pain and cramping.




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Unlike chronic fatigue syndrome (ME) and fibromyalgia these conditions generally don't have an associated multitude of other symptoms. CFS/fibromyalgia sufferers must be careful not to immediately assume they have one of these rare disorders. CFS is vastly more common than these ailments and has a different cause. For most CFS sufferers the history of their problems and blood tests can quickly rule out most of these uncommon disorders.

The treatment of all these causes depends largely on dietary and exercise/physiotherapy programs. Some have specific treatments as well. Analgesia and other pharmaceutical approaches apply to most. A definitive diagnosis is important.

If you think you could have one of these myopathies then I suggest that you see a rheumatologist who has an interest in myopathies and ask for their help in excluding them. Maybe you could take a printout of this page to illustrate what you are interested in excluding.

Disclaimer: These notes are not intended to provide personal medical advice. Such advice should be obtained personally from a qualified health professional. If you have fibromyalgia or CFS I do not advise following any of the suggestions contained herein without first consulting a suitably qualified health professional.


Disorder Type Specific Example(s) Notes 
1. Idiopathic Inflammatory Myopathies Polymyositis, 
Inclusion Body Myositis
Proximal weakness. Typical rash in dermatomyositis.
Creatine kinase blood test value usually high.
Sarcoid Myopathy Rash may be present (erythema nodosum).
Connective Tissue Diseases Blood tests show high ESR, ANA, DNA antibodies, etc.
Polymyalgia Rheumatica Proximal, limb girdle tiredness and pain. Occurs especially in elderly.
High ESR. Prednisone is often used to treat this.
2. Prescription Drugs/Alcohol.
Many prescription drugs (and alcohol) are associated with muscle pain and/or cramps. Ask your doctor.
HMA-CoA reductase inhibitors, e.g. Simvastatin, Pravastatin (anti-cholesterol agents). Elevated creatine kinase
Diuretics ("fluid pills"). May be low potassium, sodium or magnesium on blood tests.
May exacerbate dehydration.
Treatment is by supplementing and/or stopping the pill. Dietary changes may be of assistance.
Alcohol Chronic alcohol-related myopathy is usually painless. But acute painful myopathy may occur after a binge
3. Endocrine Disorders Hypothyroidism Usually high creatine kinase. A simple blood test will confirm.
Osteomalacea May get severe proximal myalgia.
Loosers zones (on x-ray) around femoral neck, pelvis, scapular, fibula or metatarsals. Vitamin D deficiency is the primary cause.
4. Metabolic Myopathies: Carbohydrate Disorders.
a). Disorders of glycogen breakdown
Myophosphorylase deficiency (McArdle's Disease).
Phosphorylase b kinase deficiency.
Pain rapidly develops in the exercising muscles, and increases with continued movement. Muscle contractures may develop. Pain after exercise may last a long time.
Resting creatine kinase usually raised. creatine kinase always raised after exercise. 
Inherited (usually autosomal recessive). 
b). Disorders of glycolysis
Phosphofructokinase deficiency
5. Metabolic Myopathies: Lipid Metabolism. Primary muscle carnitine deficiency Very rare - secondary deficiency is a lot more common. Typically painless. Manifests as progressive proximal weakness.
Lots of lipid accumulation occurs in the muscle and a low muscle carnitine level is found on testing. Carnitine supplementation is used as part of the treatment.
Carnitine palmitoyl transferase deficiency. Muscle pain during or after prolonged activity. Often present with post-exercise muscle swelling and pain. There may be a family history. A muscle specimen needs to be checked for the enzyme level to confirm the diagnosis.
6. Metabolic Myopathies: Purine Metabolism  Myoadenylate deaminase deficiency Muscle pain on exercise. Exercise intolerance and stiffness, especially in the calf muscles. Myalgia not always closely associated with exercise.
Autosomal recessive inheritance.
Muscle biopsy and analysis needed to confirm. Ischaemic forearm exercise testing can give suggestive evidence of the diagnosis.
7. Mitochondrial Myopathies. Cytochrome b deficiency Exercise intolerance and muscle pain.
Creatine kinase usually normal. Resting serum lactate may be raised. Electromyography often not very abnormal. Muscle biopsy needed to confirm.
Coenzyme Q10 may be helpful in treatment.
8. Depressive/Psychiatric Somatisation   Probably uncommon. Great caution needed here. CFS/ME sufferers and others are too often put in this category without justification. Depression/frustration is a natural side-effect of chronic pain and tiredness.  Complaints of muscle pain and severe tiredness may uncommonly be part of a mental "defence" mechanism in a person (subconsciously) wanting attention and sympathy. May be associated with low self esteem and as a reaction to mental/social/physical traumas.  
9. Central nervous system problems associated with increased muscle tone (spasticity or rigidity)  Cerebral palsy. Cerebrovascular accident (CVA or stoke).  
10. Central nervous system problems associated with excessive motor unit activity. Isaac's syndrome An unusual cause of muscle pain and cramps. Electromyography helpful. Anticonvulsants may help.

This table has been prepared largely (not completely) from the following article: Reardon K, Collins C, Byrne E, Muscle Pain and Cramps, Medicine Today, Vol. 2, No. 6, June 2001, p 20-28, Sydney, Australia.

The contents of this web page may be freely copied and distributed on the condition that it is copied and distributed in its entirety. 

Last modified: 1 June 2011.

Disclaimer: These notes are not intended to provide personal medical advice. Such advice should be obtained personally from a qualified health professional. If you have fibromyalgia or CFS I do not advise following any of the suggestions contained herein without first consulting a suitably qualified health professional.

Dr David Bird Mb.Chb.  D.C.N.  F.A.C.N.E.M. compiled the web site. Copyright 2000, David Bird. Web site address:  

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