Comorbid Conditions in Fibromyalgia and Chronic Fatigue Syndrome

When two or more distinct medical conditions occur in the same person, they are considered comorbid conditions—meaning they occur at the same time.

Fibromyalgia syndrome (FMS) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are generally considered distinct, yet overlapping—they are two different medical conditions, yet share symptoms.

But FMS and ME/CFS also have a host of comorbid (co-occurring) conditions associated with them, including other pain conditions, sleep problems, major depression, nervous system disorders, and digestive problems. Menstrual problems may also occur.

Woman with headache
Arman Zhenikeyev / Getty Images

Pain Conditions

Many people with FMS and ME/CFS also have other chronic pain conditions that need to be diagnosed and properly treated. Often, successfully treating other sources of pain can help alleviate FMS and ME/CFS symptoms.

Myofascial Pain Syndrome

Myofascial pain syndrome (MPS, sometimes called "chronic myofascial pain") is frequently confused with fibromyalgia, but they are different conditions. In MPS, muscles and connective tissues (which make up the fascia) develop what are called trigger points. A trigger point is often a small, hard knot, about the size of a pea, that you may be able to feel under your skin. Sometimes the knot itself is painful, especially when you press on it, but it often causes pain in another area.

Chronic Headaches

Some researchers believe that people with chronic headaches, such as migraines, and those with FMS may share common defects in systems that regulate specific chemical messengers in the brain, such as serotonin and epinephrine (adrenaline).

Researchers have found low levels of magnesium in both ME/CFS and migraine sufferers as well, and when chronic migraine sufferers don't respond to usual therapies, healthcare providers often consider the possibility of a more generalized pain syndrome, such as FMS. Headaches frequently occur with ME/CFS as well.

Migraine symptoms include heightened sensitivity to light and sound, nausea, vision problems such as auras or tunnel vision, difficulty speaking, and intense pain that's stronger on one side of the head.

Multiple Chemical Sensitivity

Multiple chemical sensitivity (MCS) causes similar symptoms to ME/CFS and FMS, but with the trigger being exposure to certain chemicals, such as those found in perfumes, adhesives, and cleaning products. Because everyone is exposed to a huge variety of chemicals every day, it can be extremely difficult to identify which ones are causing the problem, or even that the problem is, in fact, MCS.

Gulf War Syndrome

Symptoms of Gulf War syndrome (GWS) are strikingly similar to those of FMS and ME/CFS, including fatigue, musculoskeletal pain, and cognitive problems, and they have been shown to share a similar pathophysiological pathway. Also similar is that symptoms and their severities vary widely from person to person.

Sleep Disturbances

Sleep disturbances are considered a key clinical feature of FMS and can include insomnia, sleep apnea, and other sleep disorders. Sometimes, a sleep study reveals impaired stage-4 sleep. People with ME/CFS, however, generally have no diagnosable sleep disorders—instead, they have what's called "unrefreshing sleep."

People with FMS can also have sleep-related movement disorders.

Restless Leg Syndrome

Restless leg syndrome (RLS) is a movement disorder that causes discomfort, unease, and weariness that gets worse when you rest and feels better when you move. It can keep you awake because it's hard to get comfortable, and the movements can wake you up as well. RLS is not well understood.

Periodic Limb Movement Disorder

Periodic limb movement disorder (PLMD) is similar to RLS. People with PLMD involuntarily contract their leg muscles about every 30 seconds while they're asleep. Even if this doesn't wake you up completely, it can disrupt sleep both for you and for your sleeping partner.

Major Depression

As many as 34.8% of people with FMS are suffering from a mood disorder, specifically a type of depression. Those with more comorbidities will experience a higher risk of major depression. Researchers have outlined that depression and FMS have a similar roots and may exist on a spectrum. Moreover, FMS, ME/CFS, and major depression share many overlapping symptoms, such as difficulty concentrating and fatigue.

Major depression is much more serious than the normal periods of sadness and despondency that can go along with chronic pain and fatigue. Symptoms of major depression include:

  • Daily depressed mood
  • Loss of interest in usually pleasurable activities and interests
  • Significant weight changes
  • Insomnia or excessive sleeping
  • Constant low energy
  • Feelings of worthless or inappropriate guilt
  • Inability to make decisions or concentrate
  • Thoughts of suicide

It's crucial for people with signs of major depression to get professional help.

Possible Nervous System Disorders

Other symptoms that sometimes show up alongside FMS include:

  • Chest pain
  • Heart palpitations (irregular or forceful heartbeat)
  • Possible association with mitral valve prolapse (heart valves not closing properly)
  • A sudden drop in blood pressure 

Digestive and Menstrual Problems

While the link between FMS/ME/CFS and digestive problems isn't well understood, one theory is that it's because they're both associated with serotonin.

Irritable Bowel Syndrome

People with irritable bowel syndrome (IBS) have alternating bouts of constipation and diarrhea and have frequent abdominal pain. Other symptoms include nausea and vomiting, gas, bloating and abdominal distention.

A lot of people with IBS don't seek medical care, but it's important to do so. IBS can lead to malnutrition or dehydration (brought about by avoiding food) and depression.

Interstitial Cystitis

Interstitial cystitis (IC) is caused by inflammation of the bladder wall. It can be painful and frequently is misdiagnosed as a urinary tract infection. Many patients have IC for 10 years before they're diagnosed correctly.

Women are much more likely than men to develop IC. Symptoms include urinary frequency, urgency and discomfort; pain during intercourse; and pelvic pain.

Relief from IC is difficult as well, generally requiring a lot of trial and error before the right combination of therapies and lifestyle changes is found.

Premenstrual Syndrome/Primary Dysmenorrhea

Women with FMS or ME/CFS frequently report more problems with premenstrual syndrome (PMS) and dysmenorrhea (especially painful periods).

PMS symptoms can include:

  • Headaches
  • Abdominal cramps
  • Bloating and gas
  • Backaches
  • Swollen or tender breasts
  • Mood swings

Typically, PMS may occur during the week before a period. With dysmenorrhea, painful cramps kick in about the time your period starts and generally last 1 to 3 days. Cramps can be either sharp and intermittent or dull and achy.

Dysmenorrhea comes in two varieties: primary and secondary. Primary dysmenorrhea is the one that occurs alongside FMS and ME/CFS, and it is not caused by any identifiable problems. Secondary dysmenorrhea can be caused by infection, ovarian cyst, and endometriosis.

If you have dysmenorrhea that starts after your teenage years, you should talk to your healthcare provider about testing for an underlying cause.

Was this page helpful?
27 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Natelson BH. Myalgic encephalomyelitis/chronic fatigue syndrome and fibromyalgia: definitions, similarities, and differencesClin Ther. 2019;41(4):612-618. doi:10.1016/j.clinthera.2018.12.016

  2. Natelson BH, Lin JS, Lange G, Khan S, Stegner A, Unger ER. The effect of comorbid medical and psychiatric diagnoses on chronic fatigue syndromeAnn Med. 2019;51(7-8):371-378. doi:10.1080/07853890.2019.1683601

  3. Terzi R, Terzi H, Kale A. Avaliação da relação entre síndrome pré-menstrual e dismenorreia primária em mulheres com fibromialgia [Evaluating the relation of premenstrual syndrome and primary dysmenorrhea in women diagnosed with fibromyalgia]Rev Bras Reumatol. 2015;55(4):334-339. doi:10.1016/j.rbr.2014.12.009

  4. Goldenberg DL. Fibromyalgia: beyond the basics. UpToDate. Updated March 24, 2020.

  5. Shah JP, Thaker N, Heimur J, Aredo JV, Sikdar S, Gerber L. Myofascial trigger points then and now: a historical and scientific perspectivePM R. 2015;7(7):746-761. doi:10.1016/j.pmrj.2015.01.024

  6. Al-Nimer MM, Mohammad TM, Alsakeni R. Serum levels of serotonin as a biomarker of newly diagnosed fibromyalgia in women: Its relation to the platelet indicesJ Res Med Sci. 2018 Aug;23(1):71. doi:10.4103/jrms.JRMS_859_17

  7. Seelig M. Review and hypothesis: might patients with the chronic fatigue syndrome have latent tetany of magnesium deficiency. Journal of Chronic Fatigue Syndrome. 1998 Jan 1;4(2):77-108.

  8. Kirkland AE, Sarlo GL, Holton KF. The role of magnesium in neurological disordersNutrients. 2018;10(6):730. Published 2018 Jun 6. doi:10.3390/nu10060730

  9. U.S. Department of Health and Human Services and the Centers for Disease Control and Prevention. CFS Toolkit for Health Care Professionals: Diagnosing CFS.

  10. Schwedt TJ. Multisensory integration in migraineCurr Opin Neurol. 2013;26(3):248-253. doi:10.1097/WCO.0b013e328360edb1

  11. Rossi S, Pitidis A. Multiple chemical sensitivity: review of the state of the art in epidemiology, diagnosis, and future perspectivesJ Occup Environ Med. 2018;60(2):138-146. doi:10.1097/JOM.0000000000001215

  12. Rayhan RU, Ravindran MK, Baraniuk JN. Migraine in gulf war illness and chronic fatigue syndrome: prevalence, potential mechanisms, and evaluationFront Physiol. 2013;4:181. Published 2013 Jul 24. doi:10.3389/fphys.2013.00181

  13. Mirghani HO, Elbadawi AS. Are diabetes mellitus, restless syndrome, and fibromyalgia related?. Indian Journal of Basic and Applied Medical Research. 2016;1:2.

  14. National Institute of Neurological Disorders and Stroke. Restless Legs Syndrome Fact Sheet. Updated March 17, 2020.

  15. Kim TJ, Cha KS, Lee S, Yang TW, Kim KT, Park BS, Jun JS, Lim JA, Byun JI, Sunwoo JS, Shin JW. Brain regions associated with periodic leg movements during sleep in restless legs syndrome. Scientific reports. 2020 Jan 31;10(1):1-0. doi:10.1038/s41598-020-58365-0

  16. Vespa A, Meloni C, Giulietti MV, Ottaviani M, Spatuzzi R, Merico F. Evaluation of depression in women affected by fibromyalgia syndrome. J Depress Anxiety. 2015;4(2):178. doi:10.4172/2167-1044.1000178

  17. Ciccone DS, Natelson BH. Comorbid illness in women with chronic fatigue syndrome: a test of the single syndrome hypothesisPsychosom Med. 2003;65(2):268-275. doi:10.1097/01.psy.0000033125.08272.a9

  18. Gracely RH, Ceko M, Bushnell MC. Fibromyalgia and depressionPain Res Treat. 2012;2012:486590. doi:10.1155/2012/486590

  19. Harvard Health. Major depression. Updated December 2018.

  20. Mirza S. Rapid response: neurotransmitters: the link between depression, chronic fatigue, and chronic pain syndromes. BMJ 2015;350:h1771

  21. Wald A. Irritable bowel syndrome: beyond the basics. UpToDate. Updated Aug. 31, 2020.

  22. Keister G. Crohn's & Colitis Foundation of America. Inflammatory Bowel Disease and Irritable Bowel Syndrome—Similarities and Differences. July 2014.

  23. Parsons CL. How does interstitial cystitis begin?Transl Androl Urol. 2015;4(6):605-610. doi:10.3978/j.issn.2223-4683.2015.11.02

  24. U.S. Department of Health and Human Services. Office on Women's Health. Premenstrual syndrome. Updated March 16, 2018.

  25. Cleveland Clinic. Dysmenorrhea. Updated Nov. 20, 2020.

  26. Rowe PC, Underhill RA, Friedman KJ, et al. Myalgic encephalomyelitis/chronic fatigue syndrome diagnosis and management in young people: a primerFront Pediatr. 2017;5:121. Published 2017 Jun 19. doi:10.3389/fped.2017.00121

  27. U.S. Department of Health and Human Services. Office on Women's Health. Period problems. Updated March 16, 2018.