Introduction Selective serotonin reuptake inhibitors (SSRIs) are the recommended first-line treatment for depression. However, other classes of medications such as monoamine oxidase inhibitors are also used. These drugs alter the levels of the neurotransmitter serotonin and are associated with the occurrence of an adverse effect known as serotonin syndrome or serotonin toxicity (Wang et al., 2016). This paper reviews the article “serotonin syndrome” by Buckley et al. (2014) and describes the occurrence of serotonin syndrome, its symptoms, how a provider can diagnose the disorder in patients, treatment options, and the prevention of serotonin toxicity. Serotonin Syndrome Serotonin syndrome is a drug-generated condition associated with elevated concentrations of serotonin in the central nervous system. The occurrence of serotonin syndrome is linked to the use of serotonergic drugs, which are medications that affect the production and working of serotonin. Nonetheless, severe toxicity happens only when two or more serotonergic drugs, one being a monoamine oxidase inhibitor, are used simultaneously (Buckley et al., 2014). Moderate toxicity is documented in the overdose of one drug that exceeds the therapeutic measure and is common in 15% of treatments with SSRIs (Buckley et al., 2014; Scotton et al., 2019). Signs of Serotonin Syndrome The archetypal triad of the clinical signs of serotonin toxicity includes neuromuscular excitation, dysfunction of the autonomic nervous system, and changes in mental state. Signs of neuromuscular excitation include rigidity of muscles, overactive reflexes, and clonus, which refers to rhythmic involuntary contractions of muscles (Wang et al., 2016). The most common form of clonus is ocular, which comprises changes in eye gaze. Conversely, indications of autonomic nervous system excitation include a fast heart rate and elevated body temperatures. Agitation and confusion are the hallmarks of a distorted mental state. Serotonin toxicity begins within hours of taking medications that raise the levels of serotonin. Other symptoms that may be present in mild toxicity include nervousness, insomnia, diarrhea, enlarged pupils, and tremors (Foong et al., 2018). Severe toxicity may result in rhabdomyolysis and death. The onset of symptoms is critical to the differentiation of serotonin syndrome and neuroleptic malignant syndrome, which has a slow onset of several days. Furthermore, neuroleptic malignant syndrome presents with rigidity and extrapyramidal symptoms but does not feature clonus. Diagnosing Serotonin Toxicity A provider can diagnose serotonin toxicity by observing the presence of symptoms such as neuromuscular excitation, dysfunction of the autonomic nervous system, and changes in mental state. During the assessment, the first step is evaluating all medications being taken by the patient, including prescription medications, over-the-counter drugs, natural supplements, and illicit drugs. The clinician should also determine whether the patient suffers from other conditions such as encephalitis and convulsive seizures. The provider needs to find out whether the patient is using stimulants such as cocaine, ecstasy, cathinone, and amphetamines as well as herbal regimens such as ginseng and St John’s wort (Foong et al., 2018). Certa