Can too much serotonin be dangerous?

As one of the “feel good hormones,” it’s hard to believe you can have too much serotonin in your system.  

“Serotonin is a neurotransmitter, a brain chemical that plays a role in regulating mood, sleep and various body functions,” explains Dr. Ashley Shi, a psychiatrist at Advocate Health Care.

Proper serotonin levels help you feel happy, focused and sleep well. They also help you feel full after eating, cause your blood to clot appropriately and ensure healthy bone density. Having too little serotonin in your system may cause everything from anxiety and hyperactivity to disrupted sleep, fatigue and chronic pain. 

What happens if you have too much serotonin? 

An excess of serotonin can be toxic, leading to a condition called serotonin syndrome.  

“Serotonin syndrome can be dangerous and even life-threatening,” explains Dr. Shi. “Symptoms may include confusion, agitation, restlessness, fever, elevated pulse, sweating, diarrhea, tremors, twitching and even muscle rigidity. Because these symptoms can progress quickly, it is important to recognize and address them early.” 

It’s common for serotonin syndrome symptoms to be misattributed to other conditions, prolonging the time until a correct diagnosis and therefore increasing the risk of harm. 

The most common contributors to serotonin syndrome are SSRIs, including sertraline, escitalopram and fluoxetine. Antidepressants under the category of monoamine oxidase inhibitors (MAOIs) are often associated with the most severe cases. But serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs) and even herbal supplements can all lead to toxicity.  

It’s important to tell your health care provider everything you take in case it may elevate your risk.  

Who is at risk of serotonin syndrome and how is it treated? 

It can be difficult to predict who is likely to develop serotonin syndrome. However, having one of these risk factors can increase your likelihood:

• Aged 25 or younger
• Aged 60 or older
• Poor kidney or liver function 
• A genetically slow metabolism 

“Under medical supervision, treatment typically involves stopping the suspected medication that may have precipitated the reaction. Your health care provider will provide supportive care to stabilize symptoms,” Dr. Shi explains. “Additional treatments may include flushing your system with IV fluids or sedation to combat agitation.” 

While most cases of serotonin syndrome are mild, severe cases may require hospitalization. 

“Anyone who suspects they have serotonin syndrome should seek immediate, emergency medical attention,” warns Dr. Shi. 

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