G-string knickers can damage the skin and cause infections, experts in Germany have warned women.
German gynaecologists advised women to wear larger knickers
Dr Thomas Gent of the Association of Gynaecologists advised women to wear bigger pants to avoid complications.
He blamed the friction caused by the string part of the underwear for a big rise in the number of patients he had seen reporting genital inflammation.
A UK gynaecologist said it was the ill-fit rather than the underwear type that was probably the problem.
Dr Gent said: "G-strings can abrade and injure the sensitive skin around the genital area - especially if they are too tight or made with badly stitched material."
This damage can aid the spread of bacteria and cause fungal infections, he said.
Mr Nick Panay, consultant gynaecologist at the Queen Charlotte's Hospital, in London, said: "Certainly, if you are wearing something that is two sizes too small it could lead to abrasions and discomfort.
He said if underwear is too tight it can create an ideal environment for fungal infections, such as thrush, to grow and thrive.
"I'm sure properly fitting underwear is no problem, whether they are briefs or a G-string."