Serotonin is an important neurotransmitter that helps regulate many functions in the human body. It is often called the “happy chemical” because it contributes to wellbeing and happiness. High serotonin levels can occur naturally or as a result of medication. This article will explore what happens in the body when serotonin levels are elevated above normal.
What is Serotonin?
Serotonin is a chemical messenger that is produced in the body from the amino acid tryptophan. It acts as a neurotransmitter, meaning it sends signals between nerve cells (neurons).
Serotonin is primarily found in the gastrointestinal tract, blood platelets, and central nervous system. It helps regulate body temperature, metabolism, sleep, mood, appetite, and other cognitive functions like memory and learning.
The majority of serotonin (over 90%) is produced in the intestines. The rest is made in neurons in the central nervous system. It is released by neurons into the spaces between nerve cells called synapses. The serotonin binds to receptors on the receiving nerve cell, transmitting the signal. After signaling, serotonin is reabsorbed into the releasing neuron through reuptake transporters. This stops the signal.
Normal Serotonin Function
Under normal circumstances, serotonin levels are carefully regulated by the body. When functioning properly, serotonin plays many important roles:
– Mood – Serotonin influences mood, emotions, and happiness levels. It counteracts depression and anxiety. Low serotonin levels are linked to depression.
– Appetite – Serotonin suppresses appetite. High levels decrease appetite and food intake.
– Sleep – Serotonin promotes sleep by causing drowsiness. It also affects sleep quality and duration.
– Learning and memory – Serotonin modulates the formation of new memories and skills. Optimal levels improve focus and concentration.
– Digestion – In the gut, serotonin regulates intestinal movements and secretes digestive enzymes. It ensures healthy digestion.
– Bone health – Serotonin is needed for proper bone development and density. It regulates bone mass.
– Clotting – Platelet serotonin supports healthy blood clotting. It helps stop bleeding from injury.
– Sexual function – Serotonin influences libido and function.
– Body temperature regulation – Serotonin helps control body temperature set points.
What Causes High Serotonin?
Serotonin levels may be naturally higher in some people due to genetics or physical factors. Stress or intense exercise can temporarily boost serotonin. Certain drugs and supplements also increase serotonin by altering natural production, breakdown, or reabsorption:
– **SSRIs** – Selective serotonin reuptake inhibitor medications prevent the reabsorption of serotonin, leaving more available in the synapses. SSRIs are used as antidepressants.
– **SNRIs** – Serotonin–norepinephrine reuptake inhibitors block the reabsorption of serotonin and norepinephrine to increase their activity in the brain. SNRIs treat depression and anxiety.
– **Tryptophan** – The amino acid tryptophan is needed to produce serotonin. Consuming tryptophan from protein foods or supplements can increase serotonin levels.
– **St. John’s Wort** – St. John’s wort is an herbal supplement thought to work similarly to SSRIs by inhibiting serotonin reuptake.
– **Ecstasy (MDMA)** – The recreational drug ecstasy prompts the release of large amounts of serotonin in the brain, creating a high.
– **LSD** – LSD mimics serotonin and binds to its receptors, greatly altering mood and perception.
– **Cocaine withdrawal** – Cocaine increases serotonin. When cocaine use stops, serotonin levels crash below normal.
Signs and Symptoms of High Serotonin
The most common symptoms and side effects of excessively high serotonin include:
| System | Symptoms |
|---|---|
| Digestive | Nausea, vomiting, diarrhea |
| Nervous | Agitation, confusion, headache, irritability |
| Neuromuscular | Tremors, loss of coordination, muscle rigidity |
| Circulatory | Rapid heart rate, changes in blood pressure |
| Temperature regulation | Fever, heavy sweating |
The set of symptoms associated with severe serotonin excess is known as serotonin syndrome. This is a rare, potentially life-threatening reaction linked to certain drugs. Mild to moderate serotonin elevations cause less severe symptoms.
Mental and Emotional Symptoms
High serotonin can alter mood and mental state:
– Euphoria, excessive happiness
– Decreased anxiety
– Apathy, lack of motivation
– Poor concentration and focus
– Restlessness
– Irritability or agitation
– Disorientation and confusion
Mania or psychosis may occur in extreme cases. Hallucinations are also possible.
Physical Symptoms
Too much serotonin also causes physical symptoms including:
– Nausea, vomiting, diarrhea
– Loss of appetite
– Rapid heart rate, palpitations
– High blood pressure (hypertension)
– Dilated pupils
– Sweating, chills, goosebumps
– Tremors or muscle twitching
– Muscle rigidity, stiffness, spasms
– Lack of coordination, shakiness
Complications of High Serotonin
If serotonin levels get too high, potentially serious complications can develop:
– **Serotonin syndrome** – This is a rare but dangerous reaction caused by a sharp increase in serotonin. It requires emergency treatment.
– **Irregular heartbeat (arrhythmia)** – Excess serotonin can disrupt the heart’s electrical activity and rhythm.
– **Seizures** – Very high serotonin may lower the seizure threshold in susceptible individuals. Seizures are more likely if other drugs are also taken.
– **Changes in blood clotting** – High serotonin at the level of platelets can increase the risk of dangerous blood clots.
– **Falls or injuries** – Confusion, poor coordination, and unsteady gait from serotonin changes increase the chance of accidents and falls.
– **Aspiration pneumonia** – Vomiting while disoriented raises the risk of accidentally inhaling stomach contents into the lungs. This causes aspiration pneumonia.
– **Interactions with other drugs** – High serotonin can interact with other medications and substances. This heightens side effects.
Serotonin syndrome requires emergency medical treatment to prevent complications like organ failure, muscle tissue breakdown, and even death in severe cases.
Treatment for High Serotonin
Treatment depends on the underlying cause and severity of high serotonin symptoms:
– Mild symptoms may resolve on their own once the source of excess serotonin is stopped.
– Stopping or reducing dosage of serotonin-boosting medications under a doctor’s direction.
– For serotonin syndrome, hospitalization is needed. Treatment involves stopping the precipitating drug and giving medications like cyproheptadine or benzodiazepines to reduce serotonin activity.
– Supportive care including intravenous fluids, vital sign monitoring, temperature regulation, and medications for high blood pressure.
– Sedatives or anti-seizure medications may be used for seizures, agitation, or psychosis.
– Cooling techniques are used to treat extreme muscle rigidity and fever.
Once symptoms improve, the doctor can help determine if it’s safe to restart any psychiatric medications at a lower dose. Careful dosage adjustments and monitoring are necessary to prevent recurrence of serotonin excess.
Preventing High Serotonin
There are some precautions that can help avoid developing high serotonin:
– Don’t combine multiple drugs or supplements that increase serotonin, unless approved by a doctor.
– Start SSRIs or SNRIs at a low dose and gradually increase under medical supervision.
– Avoid excessive use of cocaine or ecstasy.
– Limit intake of tryptophan supplements.
– Be aware of serotonin syndrome warning signs – get medical help if they appear.
– Tell your doctor about all medications you take, including supplements.
– Follow dosage directions closely and don’t overuse or abuse serotonin-enhancing drugs.
Conclusion
Serotonin is an important messenger chemical that regulates many processes in the body and brain. While normal levels promote health, excessively high serotonin can occur from some supplements, medications, or recreational drugs.
Mild to moderate serotonin excess causes symptoms like nausea, confusion, anxiety, rapid heart rate, tremors, and lack of coordination. Severe elevations lead to the potentially fatal serotonin syndrome.
Treatment involves stopping medications or substances increasing serotonin, along with medications to reduce serotonin effects. Preventing high levels requires caution with combining drugs that elevate serotonin. Overall, being aware of the complications and maintaining open communication with your doctor can help avoid problems with excessive serotonin.