Navigating new cosmetic products can be a daunting and expensive task, so here is some basic ingredient information to make an informed buying decision. The short answer to whether eyelash and eyebrow enhancers really work is thankfully, yes, they do. But some work better than others and some have significant side effects or contain only a minimum of the active ingredient.

The key active ingredient is myristoyl pentapeptide- 17 (MP-17), an amino acid chain that enhances the body’s keratin production (a major component of hair). Next comes a nice mix of moisturizers and conditioners like hyaluronic acid, panthenol or a high quality oil to nourish the new growth. Finally, pick the product with enough percentage of MP-17 to actually make a visible difference. The ratio of active ingredient to filler to preservatives is what determines the price range of these products.

 Unwanted ingredients include prostaglandins or their derivatives, which require a doctor’s prescription. There is also a prostaglandin derivative available over the counter, so beware. Prostaglandins do enhance hair growth, but are also responsible for side effects such as iris discoloration, redness and irritation, and unwanted hair growth. Any cosmetic product used near the eye has the potential to cause irritation, so choose wisely.

Enhancers stimulate the hair’s keratin production, which leads to longer, stronger lashes. There are three stages of hair growth: the new hair that is growing (anagen), the mature hair (catagen) and the hair that’s getting ready to fall out (telogen). By applying an enhancer directly to the follicle, the strand receives extra keratin during the anagen (first) phase, causing it to grow stronger and thicker.

MP-17 works on the first stage of growth, and the conditioners work on the second stage to enhance and maintain those beautiful new lashes and brows. Results vary, depending on individual hair growth cycles—four to six weeks, on average. Any product that claims results any sooner than three weeks is suspect. For continued results, continuous daily application is needed (usually at night).

It is a good idea to discuss cosmetic ingredients before purchasing them with a licensed skin care professional. If they recommend a particular brand, always be sure to ask why, and if the ingredients are listed or are hidden under the “proprietary blend” guise. Also good to know is whether the manufacturer does animal testing and can stand behind their product’s results based on clinical trials.

Nadia Hlibka is a licensed aesthetician and co-owner, with Amanda Richards, of Indigo Oasis, a natural skincare salon/spa in Tucson.