The King of Pop and Prince of Plastic Surgery has sadly moonwalked to a better place. In recent years, Michael Jackson was known for his shape-shifting face just as much as his timeless songs. MJ's lips seemed to mysteriously shrink way smaller than his 50 years would naturally suggest. An unfortunate fact of life for the rest of us longing for full lips is that they grow thinner and more wrinkled with age as collagen and elastin (the fibrous proteins that fill out lips) waste away over time. But as anthropological studies suggest, the ideal female face is graced with a set of full, heart-shaped, pink lips, which connote youth and fertility. Thus, one of the greatest quests in anti-aging has become the attainment of a plumper pout.

If you're not the type to brave the scrutinizing stares of the dermatologist waiting room to get lip injections (read Kate's account here), then a lip plumping product is probably more your speed. Generally, over-the-counter lip plumpers spare you the danger of overdoing it (and subsequently sporting a duck bill for weeks on end). Because their effects are more understated and less risky, you can easily achieve a sexier, younger-looking pout within minutes. But even a tube or pot of lip plumping magic can contain dicey ingredients that should go nowhere near a mouth. What follows is a round-up of the most common ingredients in lip plumpers, how they work, and which ones are safest and most effective.

Modern technology has led to the discovery of plumping mechanisms like microspheres and the isolation of palmitoyl oligopeptides (short chains of protein fragments) to trigger the production of collagen and elastin fibers in the lips. Certain formulas use a semi-synthetic lip-plumping ingredient, such as MaxiLip (a complex containing palmitoyl oligopeptide), to stimulate collagen and boost hydration. LipFusion, one of Sephora's top-selling products, contains microscopic dehydrated collagen spheres (derived from fish) that are instantly absorbed by the lips, where they become rehydrated and help lips retain moisture. The result is fuller lips and smoothed wrinkles, but the trade-off is a heapful of parabens you'd probably rather not ingest.

The effect of microspheres and comparable ingredients is typically subtle, giving the optical illusion of shine and increased size by filling in the creases on the lips. Other than attempting to boost collagen, the most common approach of lip plumpers is to use a topical irritant that works instantly. Freeze 24/7 Plump Lips, for example, combines palmitoyl oligopeptide with niacin, a B vitamin that dilates the blood vessels and causes mild inflammation. The drawback to niacin-based treatments is that they are expensive and often aggressive, inciting a great deal of discomfort.

Some natural ingredients that work as milder irritants on the lips include cinnamon, peppermint, menthol, camphor,and caffeine. The majority of lip plumpers incorporate one or several of these ingredients to effectively irritate the lips, one of the thinnest skinned and most sensitive spots on the body. After coming into contact with an irritant, the lips redden and swell as the body sends extra blood to the area to try to protect it from harm. The enhanced blood flow in the lip area, prompted by the irritation, is what makes lips appear fuller.

Too Faced Lip Injection is based on a "medically-proven blood vessel dilating technology", which essentially boils down to some good old-fashioned cinnamon oil and cayenne pepper, a popular natural remedy for lip plumping. Another cinnamon enthusiast, Napoleon Love Bite sports cinnamon and capsicum pepper to stimulate and swell the lips. These peppers create a natural warming effect that temporarily rushes blood to the surface of lips. The typical feeling is the same as you'd get just after eating a dozen buffalo wings. But even an edible spice might cause an adverse reaction if you are allergic or have chapped lips, resulting in an inflaming and stinging sensation instead of a light tickling and plumping.

Other natural ingredients that achieve the same lip-swelling effect include wintergreen and ginger, which appear in one of the original lip plumpers on the market, DuWop Lip Venom. Sally Hansen's Lip Inflation similarly relies on ginger, in addition to peppermint and cinnamon, to achieves potent poutiness. The natural irritation trick might sound harmless enough, but beware if you have a cold sore, split, crack, or sun burn on your lips because mild stinging will turn into intolerable pain. Also, considering the grief you're inflicting on your lips, the least you can do is look for moisturizing ingredients (like vitamins and jojoba oil) and creamy bases that soothe.

If you'd rather not feel like you're smearing Tabasco sauce on your lips, the most gentle natural lip plumper is honey. This humectant draws moisture to the lip surface to hydrate, smooth, and create the appearance of plumping. Joey New York Super Duper Lips kit gives honey a starring role in its formula. Much in the same way that Be Fine Lip Serum works, lip products that tout ingredients like honey, natural emollients, and peptides will coat lips will a reflective layer that gives the impression of fullness, while at the same time possibly even stimulating the synthesis of collagen.

Although no lip plumper is going to produce the same results as synthetic hyaluronic acid gel fillers like Restylane and Hyalform, most enlarge just enough to do the trick...temporarily at least. The best you can do for your lips is to look for the purest formulas and apply plumpers with natural irritants in moderation. Overuse can lead to nasty side effects like lip ulcers at the corners of your mouth. On the other hand, if you're hoping for a collagen boost from palmitoyl oligopeptides, you'll need to use a product consistently for at least 30 days to see results.