A NEW crop of hand-held aesthetic devices has been crowding the bathroom shelf, wedged between the latest salon styling tool and multispeed electric toothbrush.

Marketed as mini-me professional devices, the gadgets often come with hefty price tags and the promise of results that sound too good to be true: a skin care brush that reduces wrinkles, a hair removal unit no bigger than an iPod that beams away unwanted hair, a slender malletlike skin plumper that creates a more youthful appearance.

The newest of these devices, boasting advanced heat and light-emitting technologies, are taking aim at acne. Products like the Tanda Skincare System ($250), the Claro ($275) and the No!No! Skin ($180), which became available in the United States this year, use heat or light, or a combination of both. They represent one of the top three categories of home-use aesthetic devices sold globally, after skin rejuvenation and hair removal devices, said Michael Moretti, an analyst and founder of Medical Insight, an aesthetic market research firm.

Keeping your face clean and stimulated with a motorized skin care brush is one thing; aiming heat or beaming colored lights to clear acne is another. Consumers and skin care professionals alike are wondering: Do these things even work?

“People with acne are desperate to try anything,” said Dan Kern, founder of Acne.org, a site that has been addressing the topic for 13 years. “Acne can be so devastating to one’s self-esteem.”

In fact, 40 million to 50 million Americans have mild to severe acne, according to the American Academy of Dermatology. “Mild” might mean a few pimples that flare up occasionally; “severe” refers to painful cysts and nodules that can leave disfiguring scars, physical and emotional.

The gold standard of treatment for severe acne has been Accutane, a powerful prescription drug also used in chemotherapy for brain and other cancers. It is associated with serious side effects, including birth defects and bowel inflammation.

Most people with acne use over-the-counter topicals like Neutrogena acne wash treatments, Clearasil or ProActiv, a skin care system sold through subscription.

Industry experts like Mr. Moretti predict that these new acne devices — many of which are similar, though not as intense, as some of the technologies used in dermatologists’ offices — are poised to become a viable part of acne regimens.

Reviews of the devices, though, are mixed.

Mr. Kern, who himself has acne, said he did not feel inclined to be hopeful about the new acne consumer devices and called the science behind them “very spotty.”

In a paper published last year in The Journal of Drugs in Dermatology, Dr. Neil Sadick, a dermatologist in Manhattan, wrote that although the exact mode of action was still unclear, it was believed that phototherapy destroyed propionibacterium acnes, the slow-growing bacteria linked to acne. Patients in his study used Omnilux Clear-U ($160) blue- and red-light therapies. Eight weeks after a monthlong treatment course, Dr. Sadick said, acne lesions were reduced by 69 percent.

But Tom Seery, founder of RealSelf.com, an online aesthetic community, reported that user reviews of home-use acne devices on his site were “a mixed bag of responses.”

Despite the fact that some of the devices have been cleared by the Food and Drug Administration, medical professionals are divided as to whether to recommend them even for spot treatments or between office visits.

“I believe that using some of these devices can significantly shrink single larger nodules and cystic nodular lesions associated with acne,” Dr. Sadick said. He added that they were probably most effective when used with other acne treatments and as “maintenance” between doctor visits. Dr. Sadick is a paid advisor to Radiancy, the maker of No! No! products for acne and hair removal, for work he has done on their hair removal products.

Rather than viewing the at-home devices as competition, Dr. Sadick noted that some of his patients had come to him by way of the devices. “I think the exposure to possible treatment of their acne through these less-powerful devices gives them hope,” he said, “and they come to me for more intensive therapies.”

Among the earliest consumer gadgets was the Zeno ($100), which came out four years ago and used thermal technology. It may have helped pave the way for other acne devices, but its efficacy has always been questioned.

“It is true that heating an acne lesion will melt the oil in the oil gland, and this will have a very modest anti-inflammatory effect,” said Dr. Macrene Alexiades-Armenakas, a dermatologist in New York. “But this is, at best, a short-term solution, mildly effective for existing pimples and time consuming because you would have to zap each pimple one at a time for at least two and a half minutes twice a day.”

Also, Dr. Alexiades-Armenakas said, using thermal therapy is not going to prevent any new pimples. “And we are a long way from proving a device like this actually works any better than applying a Q-Tip run under hot water,” she said.

The newer devices — like No!No! Skin, which emits green and red light, as well as heat, and claims to eradicate acne lesions by about 80 percent; and the Claro, which uses intense pulsed light technology and claims a 94 percent acne clearance rate — may have some validity, Dr. Alexiades-Armenakas said. “But since studies are so small-scale, the devices have yet to prove their efficacy objectively,” she said.

Green- and red-light technologies act similarly to blue- and red-light therapies to kill bacteria and promote healing of lesions. But some experts believe that intense pulsed light therapy, which emits a broad spectrum of light with each pulse, penetrates skin more deeply and may successfully treat a variety of skin imperfections, including wrinkles and a persistent red complexion.

At issue is the fact that in order to keep devices consumer-safe, without risk of burns or eye damage, manufacturers must keep the intensity of their technologies very low.

“We tested photodynamic therapy on acne patients that was a hundred times stronger than what you’d find in a home-use device, and only 40 percent of those patients responded,” said Dr. Robert Weiss, a dermatologist in Baltimore and past president of the American Society for Dermatologic Surgery. “From that clinical experience, I’m very skeptical about what these devices can do. The technology is possible, but not probable.”