Many weight loss ampoules sold online or in spas contain unlisted ingredients, including stimulants (e.g., amphetamines) or diuretics, which can cause serious side effects like heart palpitations, anxiety, or kidney strain. A 2022 study in Journal of Clinical Endocrinology found over 30% of tested ampoules contained banned substances not listed on labels. Additionally, injectable ampoules carry infection risks if not administered by licensed professionals. The World Health Organization (WHO) warns that relying on these products often leads to weight cycling (repeated loss and regain) and discourages sustainable lifestyle changes.