Online information about so-called designer vaginas is often “poor and inaccurate”, researchers said.
Websites of companies that provide female genital cosmetic surgery (FGCS) make "unsubstantiated claims" about the benefits of the procedures.
They also use confusing terminology and do not highlight surgical risks, according to the research published in BMJ Open.
Researchers from University College Hospital, London, examined the data women can access if they are considering surgery.
They performed a snapshot analysis on websites of 10 private providers that offer FGCS procedures.
They concluded: "The terminology used to describe the operations performed is confusing.
"Little information is given on short-term or long-term surgical risks either from individual clinics and their surgeons or from the medical literature.
"Unsubstantiated claims of physical, psychological and sexual benefits were present on every website."
The researchers added that it was "disturbing" that there is not a lower age limit for the surgery.
They said that in the past six years more than 300 teenage girls have had genital cosmetic surgery on the NHS.
"The absence of a lower age limit for any of the FGCS procedures is most disturbing of all," the authors wrote.
"In the past six years, 343 labiaplasties were performed in the UK NHS on girls aged 14 or under. The indications for surgery in this group of children are unknown, but labial anomalies requiring surgical interventions are extremely rare.
"In a recent observational study of referral patterns, girls as young as nine years with normal labia had presented for labiaplasty.
"The labia minora change as part of normal pubertal growth, with development completed as the individual approaches adulthood
"Given the fact that anatomy continues to change throughout the lifespan, the younger a girl begins her FGCS journey the higher the number of lifetime operations and the greater and more multiple the risks."
A Department of Health spokeswoman said: "There is no such thing as a designer vagina on the NHS.
"Of course there is cosmetic surgery carried out on the NHS, but this is only for patients who have a clinical need for it - absolutely not for those who would simply like to have it done."