What was the primary reason for fenfluramine being taken off the market in 1997?

Fenfluramine was primarily taken off the market in 1997 due to its association with an increased risk of valvular heart defects. This weight-loss medication, which was commonly used in combination with phentermine (often referred to as "fen-phen"), was linked to serious cardiovascular issues, particularly the development of heart valve abnormalities.

Clinical studies and reports indicated that patients taking fenfluramine showed an increased incidence of valvular heart disease, which led to significant concern regarding safety. This prompted regulatory agencies, including the FDA, to take action and recommend the withdrawal of fenfluramine and fen-phen from the market to protect public health.

While other side effects, such as gastrointestinal issues, could occur, they were not the primary reason for the withdrawal. Similarly, liver damage and addiction were not associated with fenfluramine in a way that warranted its removal from the market at that time. The focus on valvular heart defects encapsulates the critical safety concerns that drove the decision to withdraw fenfluramine, highlighting the importance of monitoring drug effects on cardiovascular health.