Symptoms related to increased serotonin levels include diarrhea, nausea and vomiting, restlessness, increased body temperature and heart rate, overactive reflexes, loss of coordination, hallucinations, flushing of the skin around the head and neck, and difficulty breathing. [1] X Trustworthy Source Cleveland Clinic Educational website from one of the world’s leading hospitals Go to source

Serotonin Syndrome can be a side effect of taking two or more medications that increase the body’s level of serotonin. The symptoms of Serotonin Syndrome will come on soon after taking the affecting drugs, anywhere from minutes to a few hours. [2] X Trustworthy Source Cleveland Clinic Educational website from one of the world’s leading hospitals Go to source Your doctor could also order the 5-HT level to rule out Carcinoid Syndrome. When carcinoid tumors are present, they begin to release large amounts of serotonin into the blood and you develop Carcinoid Syndrome as a result. This is a rare condition and generally effects people that are 60 years of age and older. [3] X Trustworthy Source Johns Hopkins Medicine Official resource database of the world-leading Johns Hopkins Hospital Go to source

There are no special preparations required to prepare for this test. You may experience a little bit of pain or bruising, but it will go away quickly. [4] X Research source

No matter what the results of the test are, make sure you discuss diagnosis and suggestions for treatment thoroughly with your doctor.

Agitation or restlessness Diarrhea Fast heartbeat and high blood pressure Hallucinations Increased body temperature Loss of coordination Nausea and vomiting Overactive reflexes Flushing (face, neck, or upper chest) Difficulty breathing, such as wheezing

This test is most often ordered to rule out the presence of carcinoid tumors. As they grow, carcinoid tumors secrete serotonin into the body and that excess generates a group of symptoms known as Carcinoid Syndrome. [6] X Trustworthy Source Cleveland Clinic Educational website from one of the world’s leading hospitals Go to source