NMS vs. Serotonin Syndrome: Which Is More Common and Why?

It’s been said that happiness is a state of mind. It can be affected by everything from your surroundings to the thoughts in your head. 

One of the big triggers of happiness is serotonin, which is a neurotransmitter in the brain. 

This chemical excites your brain cells and helps you feel happy; however, too much or too little can make you unhappy.

But what’s the difference between NMS and serotonin? 

You’ve come to the right place, I’ll do my best to explain this as simply as possible. 

But before discussing that, let’s quickly look at their definitions and basics.

What Is NMS?

NMS stands for Neuroleptic Malignant Syndrome, a rare but potentially life-threatening reaction to certain medications used to treat mental health conditions. 

NMS usually occurs in people taking antipsychotic drugs or other medications that block dopamine, a neurotransmitter in the brain.

Symptoms of NMS

Neuroleptic Malignant Syndrome (NMS) signs and symptoms can be severe and life-threatening. They can include:

• High fever
• Severe muscle stiffness and rigidity
• Altered mental status, such as confusion or delirium
• Irregular heartbeat
• Irregular blood pressure
• Sweating
• Tremors or shaking
• Rapid breathing
• Kidney failure

Causes of NMS

NMS is most commonly associated with using certain antipsychotic medications, such as haloperidol, fluphenazine, and chlorpromazine. 

However, it can also occur with other medications that affect dopamine levels in the brain, including anti-nausea medications and certain antidepressants.

The exact cause of NMS is not well understood, but it is thought to be related to an imbalance of dopamine in the brain. 

This imbalance can lead to the symptoms associated with NMS. 

Additionally, certain factors such as dehydration, high doses of medication, and physical exhaustion may increase the risk of developing NMS.

Treatment for NMS

According to several sources, treatment for Neuroleptic Malignant Syndrome (NMS) includes 

• Maintaining cardiorespiratory stability through mechanical ventilation
• Antiarrhythmic medications and/or pacemakers
• Maintaining electrolyte balance through IV fluids
• Lowering fever using cooling blankets, ice water, and/or ice packs
• Lowering blood pressure, if it’s elevated, through medication

Treatment may also involve the withdrawal of dopaminergic Parkinson’s medications and antiemetics that block the dopamine receptor, such as prochlorperazine, promethazine, and metoclopramide. 

Some possible precipitants of NMS include antiparkinson medication withdrawal, infection, dehydration, and surgery.

What Is Serotonin Syndrome?

Serotonin Syndrome is a potentially life-threatening condition that occurs when there is an excessive accumulation of serotonin in the body. 

Serotonin is a neurotransmitter crucial in regulating mood, appetite, and sleep.

An excessive amount of serotonin in the body can lead to a range of symptoms that can be mild to severe.

Symptoms of Serotonin Syndrome

Serotonin syndrome symptoms typically develop within hours of exposure to the drugs that cause it but can take longer. They may begin with

• Agitation
• Confusion
• Increased heart rate (tachycardia)
• Dilated pupils (mydriasis)
• High blood pressure (hypertension)
• Muscle rigidity
• Tremors
• Sweating
• Diarrhea
• Fever

Causes of Serotonin Syndrome

In general, the cause of serotonin syndrome is too much of a certain chemical, called serotonin. Serotonin is a neurotransmitter — a chemical in the brain that helps send signals between nerve cells. It’s found in many parts of the body, including:

• The gastrointestinal tract (the digestive system)
• The blood vessels
• The central nervous system (the brain and spinal cord)

This condition can occur when taking certain medications that increase serotonin levels in the body, such as selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), and serotonin-norepinephrine reuptake inhibitors (SNRIs). 

It can also occur when these medications are combined with other substances, such as illicit drugs, herbal supplements, or over-the-counter medications that increase serotonin levels.

Treatment for Serotonin Syndrome

Treatment for serotonin syndrome depends on its severity. In some cases, no treatment is needed because symptoms resolve independently. 

If you’re experiencing mild symptoms, your doctor may recommend rest and avoid any stimulants or other medications that could increase your risk of developing more serious complications from serotonin syndrome. 

If you have moderate symptoms, you may need to stop taking one or more of the medications that triggered the problem in the first place. 

In severe cases, hospitalization might be necessary so doctors can monitor your heart rate, blood pressure, and temperature closely until the symptoms resolve or medication adjustments can be made to improve your condition

Medications, such as benzodiazepines or cyproheptadine, may be used to manage symptoms such as agitation and muscle rigidity.

How Are NMS and Serotonin Syndrome Different?

NMS and serotonin syndrome are both serious conditions that can occur in people taking antidepressants. 

The two conditions are similar because they result from too much serotonin, a neurotransmitter that helps regulate mood. 

While both conditions can be life-threatening and require prompt medical attention, they differ in their onset, fever, muscle rigidity, autonomic instability, mental status changes, etiology, treatment, and mortality.

NMS is typically associated with antipsychotic medications, while serotonin syndrome is usually associated with medications that increase serotonin activity in the central nervous system. 

Treatment for both conditions involves discontinuing the offending agent, supportive care, and medication management to control symptoms.

How Are NMS and Serotonin Syndrome Similar?

NMS and serotonin syndrome are both neurological disorders resulting from excess serotonin levels in the brain. They are both rare, but they share several key symptoms.

Shared Symptoms

Neuroleptic Malignant Syndrome and Serotonin Syndrome share some symptoms, including muscle rigidity, hyperthermia, and autonomic instability.

Both conditions can also cause changes in mental status, such as confusion or delirium. 

They can also be life-threatening and require prompt medical attention.

Shared Risk Factors

There are some risk factors for NMS and Serotonin Syndrome. 

For example, both conditions can occur due to the use of certain medications, such as antipsychotics, SSRIs, and MAOIs. 

Additionally, both conditions can occur when these medications are combined with other substances.

While there are some similarities between NMS and Serotonin Syndrome, it is important to note that they are two distinct conditions with different underlying mechanisms and treatment options. 

Therefore, it is crucial for healthcare providers to accurately diagnose and differentiate between the two conditions to provide appropriate and timely treatment.

Wrapping Up

Long story short; distinguishing between NMS and serotonin syndrome can be challenging, as both conditions share some similarities in their symptoms.

However, understanding the differences between the two is critical, as the treatment approaches for each condition differ. 

If you or someone you know is experiencing symptoms that could be indicative of NMS or serotonin syndrome, seek medical attention immediately. 

Early detection and prompt treatment can make all the difference in a successful recovery. 

By staying informed and aware of the signs and symptoms, we can all work together to ensure those affected by these conditions receive the care they need to heal.