What serious effect can occur from combining Lithium with SSRIs?

Combining lithium with selective serotonin reuptake inhibitors (SSRIs) can lead to serotonin syndrome, a potentially life-threatening condition caused by increased levels of serotonin in the brain. This syndrome can manifest with a range of symptoms including agitation, confusion, rapid heart rate, dilated pupils, muscle rigidity, and seizures. The interaction occurs as both lithium and SSRIs can increase serotonin levels, and their combined effect intensifies the risk of overstimulation of serotonergic pathways.

Serotonin syndrome may emerge suddenly, often within hours of introducing or increasing the dosage of an SSRI in a patient already taking lithium. Understanding this interaction is crucial for healthcare providers to monitor and manage patients effectively, ensuring they are aware of the signs and symptoms to watch for if this combination of medications is necessary for treatment.

Other options, while possible concerns in different contexts, do not specifically result from the interaction between lithium and SSRIs. For example, acute renal failure may occur due to lithium toxicity but is not a direct result of the combination with SSRIs. Similarly, severe anxiety and hypertension might be side effects of one of these medications, but they are not the result of their pharmacological interaction.