Serotonin in Fibromyalgia and Chronic Fatigue Syndrome

Serotonin is a neurotransmitter and a hormone that helps regulate a lot of your bodily functions. Melatonin controls the entire sleep/wake cycle, while serotonin is involved more specifically in wakefulness, triggering sleep, and REM sleep. Melatonin helps you fall asleep, while serotonin helps you wake up feeling refreshed.

Tired man in suit covering eyes with hand
Dreet Production / Getty Images

A growing pool of research suggests that people with fibromyalgia (FMS) may have low levels of serotonin or low serotonin activity. Experts are split, however, as to whether serotonin levels are high or low in people with chronic fatigue syndrome (CFS or ME/CFS).

Some studies show that the problem in ME/CFS may lie in low serotonin-receptor activity, which could mean that the brain isn't using serotonin properly, even if plenty is available. A newer study suggests a possible autoimmune reaction to serotonin.

Low Serotonin

No neurotransmitter acts alone. They all work together in a complex web of activity that scientists are really just beginning to understand. Still, experts have been able to associate different neurotransmitter imbalances with certain conditions and symptoms and find some ways to help boost or decrease activity.

Serotonin activity takes place in several areas of your brain, and even elsewhere around the body (where it acts as a hormone). Those different areas of your brain use serotonin differently, and they also contain several different kinds of receptors that also influence how serotonin is used.

Serotonin deficiency is associated with many physical and psychological symptoms.

Examples of physical symptoms include:

  • Fatigue in spite of adequate rest
  • Disturbed sleep
  • Changes in appetite
  • Hot flushes and temperature changes
  • Headaches

Examples of psychological symptoms include:

  • Changes in libido
  • Mood disturbances
  • Depression
  • Irritability

When serotonin levels are extremely low, additional symptoms may include:

  • Muscle cramps
  • Bowel & bladder problems
  • Rapid, uncontrolled thought processes
  • Emotional numbness
  • Emotional or behavioral outbursts
  • Escape fantasies
  • Memory torture (dwelling on or reliving your most traumatic experiences)
  • Thoughts of harming yourself or others

Several disorders improve with medicines that increase the availability of serotonin, including depression, insomnia, restless leg syndrome, irritable bowel syndrome, headaches, obsessive-compulsive disorder, anorexia, bulimia, social anxiety, phobias, attention deficit disorder (ADD/ADHD), post-traumatic stress disorder, and alcoholism.

High Serotonin Levels and Serotonin Syndrome

Naturally occurring high levels of serotonin aren't associated with many symptoms. However, taking too much of a drug that raises serotonin levels can cause a dangerous condition called serotonin syndrome. If you suspect serotonin syndrome, you should get emergency medical help as soon as possible.

Symptoms of serotonin syndrome include:

  • Confusion
  • Agitation
  • Profuse sweating
  • High fever
  • Muscle rigidity
  • Fluctuating blood pressure

With treatment, serotonin syndrome typically resolves within a few days. In rare cases, it can be fatal.

Increasing the Availability of Serotonin

Several prescription drugs on the market increase the amount of serotonin that's available to your brain. In people with FMS and ME/CFS, the most common ones are selective serotonin reuptake inhibitors (SSRIs), such as Prozac (fluoxetine), Paxil (paroxetine) and Zoloft (sertraline); or serotonin-norepinephrine reuptake inhibitors (SNRIs) such as Cymbalta (duloxetine) and Savella (milnacipran), which are two of only three FDA-approved fibromyalgia treatments.

We don't have a lot of research confirming that food can boost serotonin levels in your brain, and it could take prohibitively huge amounts to have the desired effect. The simplest way to boost serotonin levels is by getting more sunlight.

Any time you make changes to your diet or lifestyle or take new medications, be sure to make changes slowly, and track your symptoms in a symptom journal to get an accurate gauge of what may be helping. You should always work with your healthcare provider to decide what methods to try and how successful your treatments are.

8 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. 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

  2. Maes M, Ringel K, Kubera M, et al. In myalgic encephalomyelitis/chronic fatigue syndrome, increased autoimmune activity against 5-HT is associated with immuno-inflammatory pathways and bacterial translocationJournal of Affective Disorders. 2013 May;150(2):223-230. doi:10.1016/j.jad.2013.03.029

  3. Yamashita M. Potential role of neuroactive tryptophan metabolites in central fatigue: establishment of the fatigue circuitInt J Tryptophan Res. 2020 Jun;13(1):1-12. doi:10.1177/1178646920936279

  4. Fidalgo S, Ivanov DK, Wood SH. Serotonin: from top to bottom. Biogerontology. 2012 Oct;14(1):21-45. doi:10.1007/s10522-012-9406-3

  5. Petrakis IL, Simpson TL. Posttraumatic stress disorder and alcohol use disorder: a critical review of pharmacologic treatmentsAlcohol Clin Exp Res. 2017 Jan;41(2):226-237. doi:10.1111/acer.13297

  6. Uddin MF, Alweis R, Shah SR, et al. Controversies in serotonin syndrome diagnosis and management: a reviewJ Clin Diagn Res. 2017 Sep;11(9):5-7. doi:10.7860/JCDR/2017/29473.10696

  7. U.S. Food and Drug Administration. Living with fibromyalgia, drugs approved to manage pain.

  8. Azmitia EC. Evolution of serotonin: sunlight to suicide. Handbook of Behavioral Neuroscience. 2020 Jan;31(1):3-22. doi:10.1016/B978-0-444-64125-0.00001-3

Additional Reading

By Adrienne Dellwo
Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic.