15 Clear Warnings Your Body Might Be in Serotonin Overdrive

11. Clenched Jaw or Jaw Tightness

A clenched jaw, also known as trismus, is another symptom linked to serotonin syndrome. This involuntary muscle tension occurs due to the overstimulation of muscles and nerves in the face. Patients may find their jaw muscles feel unusually tight, sore, or difficult to relax. In severe cases, this can interfere with eating, speaking, or even breathing comfortably. Jaw clenching often accompanies other muscle-related symptoms, such as rigidity or tremors, and is typically part of the broader neuromuscular effects of excessive serotonin. While jaw tightness might seem minor compared to other symptoms, it can be a significant warning sign when paired with agitation, sweating, or other indicators of serotonin syndrome. Promptly addressing this symptom and its underlying cause can prevent progression to more severe complications, such as muscle spasms or seizures.

12. Diarrhea

Diarrhea is a common gastrointestinal symptom of serotonin syndrome, often appearing as one of the earliest indicators. Serotonin’s role in the digestive system includes regulating gut motility, but an overproduction can lead to hyperactivity in the intestines, resulting in frequent and watery bowel movements. This can cause significant discomfort and may quickly lead to dehydration if left unchecked. When diarrhea is accompanied by other symptoms, such as nausea, vomiting, or abdominal cramping, it becomes an even more concerning sign of serotonin syndrome. If diarrhea occurs after starting a new medication or adjusting a dosage, it’s important to consult a healthcare provider. Addressing this symptom early can help prevent complications like severe dehydration, electrolyte imbalances, and worsening of the syndrome.