Laser treatments that are being hyped as fountains of vaginal youth are unapproved and can leave women with vaginal burns, scarring, and chronic pain, federal regulators said Monday.

U.S. Food and Drug Administration Commissioner Scott Gottlieb issued a tough warning, echoing concerns raised two years ago by the American College of Obstetricians and Gynecologists.

"The deceptive marketing of unproven treatments may not only cause injuries but may also keep some patients from accessing appropriate, recognized therapies," Gottlieb's statement said. "We are deeply concerned women are being harmed."

The FDA found reports of injuries by reviewing published studies and its database of "adverse event" reports.

The agency also sent letters to seven device makers and gave them 30 days to respond or face enforcement actions, which could include product seizures.

The laser treatments are marketed directly to women, and to doctors who buy the devices to add to their practices. The treatments claim to relieve menopausal vaginal dryness and atrophy, incontinence, and painful intercourse, as well as make the external portion of a woman's genitals look more youthful. Some pitches are aimed at breast cancer survivors who go into premature menopause because of cancer treatment; they're usually advised not to use estrogen, the standard treatment for menopausal symptoms.

The laser treatments are variously called "designer vaginoplasty," "revirgination," and "G-spot amplification." Three five-minute procedures over about three months can run $1,800 to more than $6,000, according to the North American Menopause Society. Insurance does not cover such unapproved procedures.

The FDA explained that it had approved laser and energy-based devices to destroy abnormal cervical or vaginal tissue such as genital warts or precancerous lesions. But claims that the devices can restore and rejuvenate vaginal tissue are not supported by valid studies, the agency said.

One device that has caught on, made by an Italian company and distributed in the U.S. by Hologic's Cynosure unit, is branded MonaLisa Touch.

"During a treatment, a vaginal probe is inserted into the patient's vagina, and delivers gentle, virtually painless laser energy to the vaginal wall, stimulating a healing response," MonaLisa marketing claims.

On Monday, Hologic vice president for communications Jane G. Mazur said the company takes the FDA's letter "seriously" and will work with the agency "to ensure all product communications adhere to regulatory requirements."

Warning letters also went to Alma Lasers, BTL Aesthetics, BTL Industries, InMode, Sciton, and ThermiGen.

In May 2016, the American College of Obstetricians and Gynecologists advised members that laser rejuvenation was not approved by the FDA, and that they should "be wary of adopting new or innovative approaches on the basis of promotions and marketing."

But among those who apparently did not heed the advice is Roger Lefevre, a Boston ob-gyn affiliated with the esteemed Beth Israel Deaconess Medical Center at Harvard Medical School.

Harvard Women's Health Watch, a subscription publication that promises "unbiased, well-researched information," recently ran a lengthy article featuring Lefevre's promotion of laser treatment.

"You don't have to resign yourself to live the rest of your life in a state of perpetual discomfort," the article quoted him as saying.