Lip-plumping products – the popular glosses and “pre-lipsticks” intended to maximize a person’s pout – reached critical mass a few weeks ago when a lab technician on the popular television show “CSI: Miami” decoded sticky red smears on a pair of boxer shorts belonging to a young murder victim: “It’s lip plumper. Our first suspect uses lip plumper,” she announced to the sexy criminologists. Turns out the smears came from the lips of a high-school science teacher.

The Fall 2004 Bliss cosmetic catalog conducted “lab testing” of its own – on Lip Explosion Vorexin Gel – and “measured up to a 40% fuller pout.” The LVMH owned spa and cosmetic company offers six other brands ranging in price from $25 to $80. Sephora’s catalog offers even more: at last count the cosmetics emporium carried 20 different lip plumpers, among them City Lips by City Cosmetics ($29), Alpha Lipoic Acid Lip Plumper by celebrity dermatologist N.V. Perricone, M.D. ($33), Venom Gloss by DuWop ($16), and Lip Injection by Too Faced ($18.50). The last purports to use a “patented formula … based on medically-proven blood vessel dilating technology that fills the lips with a lasting rush of blood to create the sexiest pout this side of a plastic surgeons office!” Who needs plastic surgery or cosmetic dermatology when a half-ounce tube will do?

Chemistry, it would appear, is leaps and bounds ahead of the 1860s, when ladies would mouth the word “prisms” in private to encourage bee-stung lips. “The common practice was to repeat in sequence a series of words beginning with p; this would have the effects of rounding and puckering the mouth,” historian Lois Banner wrote in her 1983 study “American Beauty.” “‘Peas, prunes, and prisms’ were the most popular words in the sequence, although ‘potatoes’ and ‘papa’ were sometimes added.”

But according to author and consumer advocate Paula Begoun, the self-titled “Cosmetics Cop” who has sold more than 1 million copies of her product guide, “Don’t Go To The Cosmetics Counter Without Me,” lip plumpers are just another instance in a long line of unregulated cosmetics that are legally permitted to make false claims, what the Food and Drug Administration and beauty industry call “puffery.” Ms. Begoun cited the Joey New York Super Duper Lip Kit as an example: “Serious snake oil,” she said in a phone interview last week. She lists the ingredients in her guide: sugar, glycerin, honey, “and a tiny amount of AHA [alpha-hydroxy acid], which might make lips softer but certainly not fuller. … It’s an utter work of fiction.” Joey New York claims that its product will dramatically enhance lips, “making them fuller, smoother, softer” – and, of course, plumper.

Lip plumper may not be in the same league as Lash Lure and Koremlu depilatory, two popular cosmetics that actually blinded and crippled women in the 1930s with aniline and rat poison, respectively. But despite certain safety measures, cosmetic companies remain free to make medical-sounding and puffed-up claims – to the great detriment of consumer wallets.

The FDA’s regulations state that the definition of a drug is an article “intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease … or intended to affect the structure or any function of the body.” Lip plumpers certainly claim to affect the structure of the body. And with doctor’s endorsements and the need for a Ph.D. in chemistry to evaluate a product’s ingredients list, it’s getting more and more difficult to distinguish the snake oils from the legitimate products from the FDA-approved drugs. In fact, six out of 10 people, according to a survey conducted in 2004 by Harris Interactive for the National Consumers League, believe that the FDA monitors how well over-the-counter creams work. “Image is what the cosmetic industry sells through its products, and it’s up to the consumer to believe it or not,” said John E. Bailey, the former director of the FDA’s division of Color and Cosmetics, quoted in a memo titled “Understanding Puffery,” posted on the FDA’s Web site. “Most cosmetics contain ingredients that are promoted with exaggerated claims of beauty or long-lasting effects to create an image.”

Elizabethans may have had a better chance at lip plumping with their concoctions of plaster of Paris and red dye, rolled into a crayon and dried in the sun.

Dr. N.V. Perricone has argued publicly that turning his compounds into prescription drugs and subjecting them to FDA approval would entail costly and extensive research, driving the prices of good skincare products and cosmetics even higher than they already are.

Dr. Leslie Baumann, director of cosmetic dermatology at the University of Miami School of Medicine, agreed: “FDA approval would delay many good products from reaching consumers.” However, she does believe that it is getting increasingly difficult for consumers to understand the scientific claims: “The old cosmetics ads used to just say: ‘using this cream will keep your husband from straying, use our product to stay beautiful.’ Now there are ads that rely on science, like those popular ads for StriVectin. The marketing can be misleading and the consumer can be confused in thinking effectiveness has been proven,” she said.

“If you want the appearance of fuller lips, then get collagen injections,” said Ms. Begoun, a professionally trained makeup artist, with a laugh. “Or you can line the outer corners of your lips with a lip pencil a few shades darker than your lipstick.”

Something a fictitious science teacher on “CSI” should have known.