Are breast enlargement supplements safe? i.e. bountiful breasts

Waste of money: They don't work. Save your money.

Many but effects?: I am sure that there are many that make these claims, however, the effects will vary from virtually no side effects or results to more extensive effects particularly if they are hormonal analogues, with similar effects to oral contraceptives or estrogen replacement with head aches, weight or fluid gain, tenderness, masses, increased clotting tendencies, etc. I am not aware of any good science.