Which of the following medications can lead to serotonin syndrome when taken with MAO inhibitors?

Tricyclic antidepressants are the correct choice as they can lead to serotonin syndrome when taken with monoamine oxidase inhibitors (MAO inhibitors). Serotonin syndrome is a potentially life-threatening condition resulting from an excess of serotonin in the brain, which can occur when multiple medications that increase serotonin levels are used concurrently.

Tricyclic antidepressants, such as amitriptyline and clomipramine, work by inhibiting the reuptake of neurotransmitters, particularly serotonin and norepinephrine, which enhances serotonergic activity. When combined with MAO inhibitors, which prevent the breakdown of serotonin, the risk of excessive serotonin accumulation and the resulting syndrome increases significantly.

This interaction does not apply to the other options. Ibuprofen, while it is an anti-inflammatory medication, does not affect serotonin levels and thus does not contribute to serotonin syndrome. Beta blockers are primarily used to manage cardiovascular conditions and do not have a significant impact on serotonin levels either. Antacids work by neutralizing stomach acid and have no interaction with the serotonergic system. Therefore, among the choices provided, tricyclic antidepressants are the only ones that pose a risk of serotonin syndrome when taken with MAO inhibitors.