Which medication should be avoided when taking lorcaserin for weight loss?

Lorcaserin, a medication used for weight loss, influences serotonin receptors in the brain, particularly the 5-HT2C receptor. Because of its mechanism of action, taking lorcaserin alongside other medications that also affect serotonin levels can heighten the risk of serotonin syndrome, a potentially life-threatening condition characterized by excessive accumulation of serotonin in the central nervous system. Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, increase serotonin levels and therefore can interact adversely with lorcaserin.

Medications like ibuprofen, metformin, and aspirin do not have significant interactions with lorcaserin regarding serotonin levels. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) used primarily for pain relief, metformin is commonly prescribed for managing type 2 diabetes, and aspirin serves as an antiplatelet agent. While they may have their own side effect profiles, they do not present the same risk of serotonin syndrome when taken with lorcaserin.

Therefore, the recommendation to avoid SSRIs, including fluoxetine, when taking lorcaserin is based on the potential for dangerous interactions that could lead to serious health complications.