What side effect should a nurse monitor for in a client taking St. John's wort with citalopram?

When a client is taking St. John's wort alongside citalopram, the primary concern is the risk of serotonin syndrome. St. John's wort is a well-known herbal supplement that can increase serotonin levels in the brain. Citalopram, a selective serotonin reuptake inhibitor (SSRI), also acts to elevate serotonin levels. When these two substances are combined, the cumulative effects can lead to excessive serotonin activity, resulting in serotonin syndrome, a potentially life-threatening condition. Symptoms of this syndrome can include confusion, agitation, rapid heart rate, increased body temperature, and tremors.

Monitoring for signs of serotonin syndrome is crucial, especially given the interaction between St. John's wort and citalopram, as this combination alters the normal serotonergic balance in the body. Proper education about the risks and symptoms should also be provided to the client to ensure prompt recognition and intervention.