Serotonin is an important neurotransmitter for regulating mood and sleep, but having too much Serotonin in your brain or body can be dangerous or even fatal.
Serotonin is a neurotransmitter synthesized in the brain and the intestines. This neurotransmitter is responsible for a number of different bodily functions, including the regulation of temperature, mood, sleep and appetite.
Serotonin also plays a role in memory, learning and other cognitive functions, as well as breathing, blood flow and digestion. While a certain amount of Serotonin is required for the body to function properly, having too much Serotonin, or conversely having low levels may cause a number of problems.
However, when levels are too high, various adverse reactions can occur. In some cases, high levels of Serotonin can lead to a condition known as “Serotonin Syndrome” or “Serotonin toxicity,” which has the potential to be fatal.



- Increases Serotonin levels in the brain
- Enhances mood and alleviates stress
- Improves sleep and regulates appetite
Symptoms of Too Much Serotonin
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If you have too much Serotonin, side effects can be mild to severe. Symptoms of too much Serotonin including the following:
- Goosebumps
- Shivering
- Muscle stiffness
- Twitching muscles
- Loss of coordination
- Heavy sweating
- Dilated pupils
- High blood pressure
- Rapid heart rate
- Confusion
- Restlessness
- Agitation
Most of the above symptoms are related to the effects Serotonin has as a neurotransmitter in the central nervous system. However, because Serotonin can act as a hormone in other parts of the body besides the central nervous system, effects may be felt other places as well.
The vast majority of Serotonin in the body is found in the gastrointestinal system. Only approximately 10% of the Serotonin in the body is found in the brain and central nervous system, and the other 90% is found in the gut.
Symptoms of too much Serotonin in the gut include nausea, abdominal cramps, heartburn, flatulence, vomiting, and diarrhea.
In extreme cases, Serotonin toxicity or a condition known as Serotonin Syndrome may be diagnosed. Signs of these conditions may include:
- High fever
- Irregular heartbeat
- Seizures
- Loss of consciousness
Research studies have also found a connection between too much Serotonin and anxiety. While many people take Serotonin-boosting supplements or drugs to improve mood and anxiety, if you feel agitated or nervous after using these agents, it may be a sign of too much Serotonin in the brain.
Too Much Serotonin Causes
High levels of Serotonin and Serotonin toxicity occur any time the concentration of Serotonin in the body exceeds the safe, normal amount. These symptoms may also occur if Serotonin receptors in the brain are over-stimulated by chemical agonists.
Serotonin toxicity typically occurs when an individual raises his or her level of Serotonin artificially by taking substances that increase the production of or prevent the reabsorption of this neurotransmitter.
Although some people may develop symptoms of high Serotonin when taking only one medication or substance that raises Serotonin levels, this condition is much more likely to occur among people who are taking two or more medications or substances that affect serotonergic activity.
Serotonin Syndrome may also occur when an individual takes more than the recommended amount of a single medication or combines medications that raise Serotonin levels.
Examples of medications that may raise Serotonin levels or activity, or block the reabsorption of Serotonin in the body include:
- Selective Serotonin reuptake inhibitors (SSRIs)
- Serotonin and Norepinephrine reuptake inhibitors (SNRIs)
- Certain pain medications
- Anti-migraine medications
- Monoamine oxidase inhibitors (MAOIs)
- Tricyclic antidepressants
- Bupropion
- Anti-nausea medications
- Over-the-counter cold and cough remedies that contain dextromethorphan
- Some illicit drugs
- Lithium
- Ritonavir
- Linezolid
- St. John’s wort
- Nutmeg or ginseng supplements
- 5-HTP and L-Tryptophan supplements
The risk of too much Serotonin increases when any of these medications or substances are used in combination with one another.
Treatment for Serotonin Toxicity
Mild cases of elevated Serotonin will typically resolve themselves within 72 hours of discontinuing the medication that caused the condition, unless the medication was an SSRI.
These medications remain in the system for a longer period of time after discontinuation, so the symptoms of elevated Serotonin may take weeks to resolve completely if an SSRI was involved.
If you notice Serotonin toxicity symptoms in yourself or a loved one, immediate medical attention is required. Depending on the severity of the symptoms, treatments for Serotonin toxicity may include:
- Breathing tube – If your breathing isn’t well regulated, a breathing tube may be required.
- Medication to relax muscles – If you are experiencing seizures or muscle stiffness, muscle relaxants may be administered.
- Blood pressure medications – Medications designed to lower blood pressure and/or heart rate are often necessary for patients with Serotonin syndrome. Conversely, some patients with Serotonin Syndrome require medications to raise their blood pressure.
- Intravenous fluids – If you have a fever or dehydration because of high serotonin levels, IV fluids are beneficial.
- Oxygen – Some patients require an oxygen mask to maintain normal blood oxygen levels.
- Medications to block Serotonin production – If your condition is severe, medications to slow or stop the production of Serotonin will be administered.
Can 5-HTP and L-Tryptophan Cause Serotonin Toxicity?
Just as high levels of Serotonin are dangerous, low levels of Serotonin can cause symptoms as well.
People who believe they have low Serotonin levels often take supplements to increase the production of Serotonin in their bodies. The most common supplements taken for this purpose are 5-HTP and L-Tryptophan.
Because both 5-HTP and L-Tryptophan supplements increase the body’s production of Serotonin, individuals who consume these supplements are at risk of developing higher than normal levels of Serotonin.
When taken as recommended, however, the risk of Serotonin toxicity is relatively low with these natural supplements.
The risk of problems increases significantly when 5-HTP or L-Tryptophan supplements are taken in large doses or in combination with other medications or substances that raise serotonin levels.
To avoid accumulating too much Serotonin, Serotonin boosting supplements should be taken only under the supervision of a medical professional. In addition, anyone who notices the symptoms of Serotonin Syndrome or toxicity should seek medical attention right away.
- http://www.mayoclinic.org/diseases-conditions/serotonin-syndrome/basics/treatment/con-20028946
- http://www.mayoclinic.org/diseases-conditions/serotonin-syndrome/basics/definition/con-20028946
- http://www.mayoclinic.org/diseases-conditions/serotonin-syndrome/basics/symptoms/con-20028946
- http://articles.mercola.com/sites/articles/archive/2015/07/02/social-anxiety-disorder.aspx
Article last updated on: March 12th, 2018 by Nootriment