Serotonin Syndrome Vs. NMS: Here’s Everything You Need To Know!

The nervous system is the most important body element that connects to all body parts and provides signals to the brain for doing, thinking, and performing any task.

Serotonin syndrome and neuroleptic malignant syndrome( NMS) are the interactions of drugs when taking medicines for mental disorders.

It is sometimes life-threatening and can cause serious implications to the health and mind of the individuals. 

Moreover, differentiating between these serious disorders is crucial due to understanding the differences in their management and treatment.

However, treatments and diagnosis can be overwhelming as the features, types, and treatments are totally different from one another.

If you are looking for the basic differences between these two neuro disorders and how they can be prevented, then let’s explore through this article.

What Is Serotonin Syndrome And How Does It Affect Health?

Serotonin Syndrome And Health

Serotonin syndrome is the condition when drug interactions called serotonergic take place. When these drugs interact in the body, it causes excess serotonin in the central nervous system (CNS).

Also, it can also precipitate serotonin syndrome and can lead to many problems to health and mind. Also, it can happen due to many reasons, such as accidental interactions between medications or recreational drugs, therapeutic medication use, or intentional overdose.

So, proper consultant and doctor advice needs to be taken into account to avoid further complications to health.  

What Is Neuroleptic Malignant Syndrome (Nms) And Its Effects On Health?

Neuroleptic Malignant syndrome (NMS) is another interaction of the idiosyncratic reaction to antipsychotic drugs. It can be life-threatening and sometimes based on the presence of certain historical, physical, and laboratory findings.

Moreover, these drug interactions have certain reactions that are characterized by fever, altered mental status, muscle rigidity, and other harmful effects.

Again, it can cause serious implications on the brain by irreversible brain injury from hyperthermia. It affects the nervous system, which prevents proper functioning of the brain and body.  

What Are The Causes Of Serotonin Syndrome And NMS?

Serotonin Syndrome is the drug interactions that worsen if left untreated. Besides, many drugs potentially interact and cause serious problems, even death. So, knowing the signs and symptoms is necessary to have proper treatments. Some signs are,

  • Suffer from agitation or restlessness.
  • You may suffer from insomnia, confusion, and rapid heart rate.
  • There can be high blood pressure, and you may see dilated pupils.
  • Also, there is a loss of muscle coordination or twitching muscles.

Similarly, Neuroleptic Malignant Syndrome( NMS) is a similar condition that happens due to drug interactions called antipsychotics (FGA, SGA).

When there is rapid escalation of dosing or taking medicines, having other agents simultaneously can provide you with interactions. Some of the symptoms that are associated with NMS are,

  • You are having a very high heartbeat and fever.
  • You can see fluctuations in the high blood pressure and low blood pressure. 
  • There can be uncertain muscle rigidity or flexibility. 
  • You can suffer from excessive sweating, mood changes, or other issues. 

What Diagnosis And Treatments Are Associated With Serotonin Syndrome And NMS?

Serotonin syndrome and NMS are closely associated with each other as both affect the brain and the nervous system.

However, the diagnosis and treatment vary because they show different signs and symptoms. Moreover, the diagnosis is confirmed by different methods, such as

  • The presence of recent treatment with neuroleptics (within the past 1-4 weeks)
  • Hyperthermia (temperature above 38°C)
  • And muscular rigidity. 

Further, it shows some of the following features,

  • You can find changes in mental status and Tachycardia.
  • It might cause hypertension or hypotension.
  • There can be diaphoresis or sialorrhea, tremors, incontinence, and increased creatine phosphokinase (CPK) or urinary myoglobin levels. 

After proper diagnosis, the doctor goes with further treatment that includes medications and observations. Some other ways of treating serotonin syndrome and NMS are the following,

  • Doctors can suggest the discontinuation of serotonergic agents or medications.
  • They will also provide supportive care with IV fluids, oxygen therapy, and continuous cardiac activities. 
  • Moreover, when the patient is suffering from hyperthermia, then doctors may suggest standard methods by avoiding antipyretics and other interactive drugs. 
  • Cyproheptadine measures could be taken if the patient is still showing symptoms of failure or improved vital signs. 

How Are Serotonin Syndrome And NMS Differentiated From One Another?

Serotonin syndrome and NMS are the serious complications of medications that are associated with mental illness.

But they show some differences that make them different from each other, which are given below,

  • Serotonin Syndrome and NMS is an uncommon and life-threatening medicine-induced disorder that affects the nervous system and brain. Moreover, it shares some of the differences that differentiate each other.
  • The identical features of Serotonin interactions are about 1 to 3 days, which shows a vital stage varies and shows symptoms like Hypertension, Tachycardia, Tachypnoea, and Hyperthermia (> 40°C). Similarly, the variable time for NMS is measured up to 12 hours and can be treated with Serotonergic Agents.
  • Moreover, some of the overlapping features of NMS and serotonin syndrome can be critical and give overwhelming situations to the minds and health of individuals.
  • It can make skin suffer from diaphoresis and affects mental status with variable stupor, coma, alert, and other issues. Similarly, it affects muscles with rigidity, increased tone, and pain, especially in the lower extremities. 
  • Some of the distinct features that they share are reflexes with hyporeflexia, normal pupils, and bowel sounds that can go with normal or decreased. 


Serotonin syndrome and NMS are serious drug interactions that happen due to adverse reactions associated with psychotropic medications.

Moreover, the above causes, treatments, and differences associated with these two serious mental illnesses give the best solutions and bring back the lives of individuals.

Moreover, serotonin disorders are connected with restlessness, agitation, HTN, Tachycardia, diarrhea, tremor, myoclonus, hyperreflexia, diaphoresis, hyperthermia, and tachypnea.

Similarly, symptoms or signs of NMS show the same as with Serotonin syndrome but interact with different medicines. So, clinicians better understand the situations and treat them effectively to make the person fit and fine from mind and body.


  • Modi S, Dharaiya D, Schultz L, Varelas P. Neuroleptic Malignant Syndrome: Complications, Outcomes, and Mortality ( Neurocrit Care. 2016; 24(1): 97-103. Accessed 4/12/2022.

Dr. Nicola Fawcet is a highly regarded Consultant in General Medicine known for her expertise in providing comprehensive medical care with a focus on holistic patient well-being. With a passion for internal medicine, Dr. Fawcet has dedicated her career to delivering high-quality healthcare and improving patient outcomes.

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