Serotonin Syndrome

By | June 10, 2022

The hormone serotonin is popularly known as the happiness hormone par excellence: it lifts the spirits and puts you in a good mood. But what happens when it is present in a very large amount in the body? Then it not only damages our health, but in the worst case even puts our lives in danger. Serotonin syndrome is therefore a serious condition.

What is Serotonin Syndrome?

Serotonin syndrome is a syndrome that is associated with various symptoms. This disease is caused by the accumulation of the hormone serotonin, which acts both as a tissue hormone and as a neurotransmitter and influences a wide variety of bodily functions. As a neurotransmitter, serotonin is located in the central and peripheral nervous system. For chd in dictionary, please visit

There it takes over the task of activating many different receptors. As part of the central nervous system, it controls our attention and mood, for example, and is also responsible for regulating body heat. In the peripheral nervous system, it affects the movement of the gastrointestinal tract, bronchial and skeletal muscles.

In an appropriate amount, serotonin is vital for the human organism. The term “serotonin syndrome” was coined by H. Sternbach, who first described the three typical symptoms of serotonin syndrome in 1991.


Serotonin syndrome is a disease that arises as a result of a disruption in the central or peripheral serotonin receptors. According to Sternbach, the disease also occurs after administration of a drug that increases serotonin levels. Therapy with triptans or antidepressants, for example, causes mild symptoms.

And often the serotonin syndrome is caused by the interaction of different drugs. If several serotonin-stimulating drugs are used in combination, the increased serotonin release can even have life-threatening effects. The interaction between serotonin-stimulating drugs and certain foods should also not be underestimated.

Symptoms, Ailments & Signs

Serotonin syndrome can vary in severity for each patient. It can also occur in people of all ages. How bad the symptoms actually are can also be related to the triggering drug. There are a number of typical signs of serotonin syndrome. The symptoms are divided into three categories:

Mental disorders: confusion, agitation, restlessness, disorientation and feelings of anxiety. 2. Autonomic disorders: increased, profuse sweating, chills, tachycardia (cardiac arrhythmia), hyperthermia (severely rising body temperature), hypertension (high blood pressure) as well as diarrhea and vomiting. 3. Neuromuscular disorders: involuntary and spasmodic muscle twitches, tremor (hyperactivity with shaking) and hyperreflexia.

The symptoms mentioned can appear just a few hours after taking a drug or combination of drugs or after increasing the dose. As a rule, the serotonin syndrome becomes noticeable within 24 hours, in about 60 percent of all patients even within six hours. And it is precisely on this point that the serotonin syndrome differs from the neuroleptic malignant syndrome, which is accompanied by very similar symptoms.

However, in the case of neuroleptic malignant syndrome, the first signs appear much more slowly and can only be observed a few days after taking the drug. In the worst case, serotonin syndrome can put the patient’s life in great danger: severe cardiac arrhythmia, hyperthermia above 41 degrees Celsius and hypertensive crises are life-threatening forms of serotonin syndrome that can trigger cardiogenic shock.

Diagnosis & course of disease

Not infrequently, mild manifestations of serotonin syndrome are overlooked – quite simply because the disease is not yet widely known and the symptoms are quite unspecific. In addition, the symptoms are often not associated with the use of medication. The serotonin syndrome can be diagnosed quite well with the help of the medication history.

One method of detecting serotonin syndrome is called differential diagnosis, which excludes neuroleptic malignant syndrome, malignant hyperthermia, poisoning, sepsis, meningitis, tetanus and mental illnesses such as depression.


Serotonin syndrome can cause mental, autonomic, and neuromuscular disorders. Mental disorders include feelings of anxiety and restlessness. The autonomic disorders include complications such as cardiac arrhythmias, gastrointestinal disorders and high blood pressure. The neuromuscular disorders are the most severe – spasmodic muscle twitching, tremor and hyperreflexia are among the complications.

If the syndrome is not treated promptly, it can also lead to a fever over 41 degrees Celsius, a sudden increase in blood pressure and other life-threatening complications. In extreme cases, the symptoms mentioned trigger a cardiogenic shock, which can lead to shortness of breath, pulmonary edema and finally heart failure. Severe symptoms can also lead to multiple organ failure, which is usually also life-threatening.

Further complications can occur during treatment, either due to surgical interventions such as percutaneous coronary intervention or the accompanying medication prescribed. Above all, thrombin inhibitors and anti-inflammatory drugs pose risks, which can further damage the already stressed cardiovascular system. When using a balloon pump, there is a risk of damaging the vessels. Infections, wound healing disorders and allergic reactions can also occur, which are associated with further complications.

When should you go to the doctor?

Serotonin syndrome should always be treated by a medical professional. As a rule, this disease cannot be healed on its own, so that the person affected is always dependent on medical treatment. In order not to limit life expectancy, a doctor should be consulted at the first signs of this disease. A doctor should be consulted for serotonin syndrome if the person concerned suffers from mental disorders. This leads to disorientation or inner restlessness.

Furthermore, permanent vomiting or diarrhea can indicate serotonin syndrome and must be examined by a doctor. Permanent trembling in the hands is also often an indication of the disease and requires a medical examination. In many cases, depression can also indicate serotonin syndrome. In the case of serotonin syndrome, the family doctor can be consulted. Further treatment is usually carried out by a specialist. It cannot be universally predicted whether this will lead to complete healing.

Treatment & Therapy

To treat serotonin syndrome, the first thing to do is fight the trigger. This means that if a drug is to blame for the disease, it must be discontinued immediately. Instead, the patient is prescribed another medication. At the same time, his state of health is closely monitored.

This is the only way to stop the overproduction of serotonin. In mild cases, improvement occurs within 24 hours. Medications can also be administered to treat the symptoms. Thus, with a mild manifestation of the syndrome, lorazepam is mainly prescribed. This medicine is for general sedation only.

In moderate to severe disease, the doctor administers cyproheptadine, for example, to inhibit the effects of serotonin in a non-specific way. However, autonomic disorders are not easy to treat. This is the case, for example, when the blood pressure suffers from strong fluctuations. And if even life-threatening symptoms such as hyperthermia, kidney failure or aspiration occur, emergency measures are of course used.

Unlike fever, hyperthermia is not due to the disturbed temperature regulation in the hypothalamus, but to the uncontrolled increased activity of the muscles. Therefore, treatment with paracetamol makes no sense in this case. Drugs with a long duration of action or a long half-life are particularly dangerous.

They need several days to restore the full activity of the affected enzymes. The symptoms persist for several days to weeks after stopping the trigger drug. Dangerous agents include, for example, fluoxetine, whose half-life is one week.


If a patient tolerates an antidepressant particularly well, then the risk of serotonin syndrome is high. It is therefore advisable that he pays attention to any physical changes. In this way, the first signs of illness can be recognized early and discussed with the doctor. The same applies after increasing the dose of a drug. In addition, caution should also be exercised when self-medicating with preparations containing St. John’s wort extracts, dextromethorphan or tryptophan, since these active substances promote the production of serotonin.


Serotonin syndrome causes physical, neurological and psychological problems. Follow-up care is advisable to counteract the symptoms even after the treatment has been completed. The syndrome should not occur again in the future. The focus here is on the quality of life of those affected.

Serotonin syndrome can have a variety of causes. There is no universal trigger. The causative disease is treated with medication. During follow-up, the doctor will reduce the dose to the point of discontinuation. He also checks to what extent the patient tolerates the medicine. The condition of the person concerned is recorded in regular checks. If the symptoms recur, the treatment starts again. Further examinations are necessary at the discretion of the specialist (differential diagnosis).

Neurological symptoms are accompanied by cramps or limb tremors. In severe cases, the respiratory muscles are affected. This situation is life-threatening for the person concerned. A hospital stay is urgently needed. Follow-up care takes place in the hospital. It ends when there is no longer any danger to life and the patient is allowed to leave the clinic again.

There is a connection between serotonin syndrome and an increased risk of suicide. If there is an acute risk of suicide, the emergency services must be called immediately. He provides first aid. If the danger persists, the victim is admitted to the hospital.

You can do that yourself

Since this disease can be fatal, it is essential to seek medical treatment. Spontaneous healing is not possible. It is also important to find out which medications caused the syndrome in the patient. They must be removed or replaced. This is the only way to improve the symptoms and prevent a renewed increase in serotonin.

To do this, it is necessary for the affected patient to state which medication he has taken. This also applies to over-the-counter products, such as St. John’s wort preparations. They also increase serotonin and may have contributed to a dangerous interaction.

If patients with serotonin syndrome are not already in psychotherapeutic treatment, they should start now at the latest. This can prevent future depression and enable patients to live without taking serotonin-boosting drugs.

A change in lifestyle also has an antidepressant effect. Regular endurance sports, for example, regulates the metabolism and at the same time ensures a good mood. According to studies, a conscious, balanced diet also has a positive effect on existing depression and prevents it. Avoiding stimulants such as nicotine or alcohol and regular rest and sleep times also help the patient to remain mentally stable. Many people also benefit from self-help groups. Voluntary work also gives life new meaning.

Serotonin Syndrome