Premature thelarche related to fennel tea consumption?

Isolated premature thelarche is the breast development in the absence of other secondary sex characteristics in prepubertal girls. Fennel is a plant which contains a phytoestrogen called anethole as an active ingredient.

Here, we report a case of a 12-month-old girl who showed breast development that became apparent in the last 3 months. Her medical history revealed that she was given two to three teaspoons of fennel tea by her mother every day for restlessness for the last 6 months. Isolated premature thelarche was diagnosed based on physical and laboratory findings. On follow-up, after cessation of fennel consumption, the breast development of the patient regressed gradually and became normal by the end of 1 year.

Reporting this case, we want to emphasize the importance of awareness of fennel tea, a commonly used plant in babies, as a preventable cause of premature thelarche.