Thai health authorities are warning of potentially irreversible ill effects for people undergoing penis and labia lightening procedures.
The BBC reports Lelux Hospital has been offering the service using lasers to lighten the shade of patients' genitals for several months.
Originally the clinic only offered vagina whitening, but expanded to penis whitening after men began to enquire about the process.
"They are popular among gay men... who take good care of their private parts. They want to look good in all areas," the hospital's marketing manager Popol Tansakul told the BBC.
The procedure involves using lasers on the genitals to break down melanin in the skin, leaving a significantly lighter shade.
The hospital's skin and laser department manager, Bunthita Wattanasiri, told AFP they had up to 100 clients a month, three to four a day coming for the procedure.
However the Thai health ministry is warning against the procedure, calling it dangerous and unnecessary.
"Penis laser whitening is not necessary, wastes money and may give more negative effects than positive ones," health ministry representative Dr Thongchai Keeratihuttayakorn said in a statement.
The ministry is warning possible side effects could include pain, inflammation, scars and possible detrimental effects on the reproductive system and sexual performance.