Effective Skin Care for Women
An overview of key strategies for maintaining healthy skin
Every day in our dermatology practice, women of all ages ask what they can do to achieve and maintain healthier-looking skin. Women are inundated with creams, lotions, and serums touted to reverse the signs of aging and sun damage. Unfortunately, many of these claims are completely unsupported or are backed by small, uncontrolled studies that have not been scrutinized by the FDA. Although prescription topicals must undergo rigorous FDA-monitored examination, nonprescription topicals — known as cosmeceuticals — are not subject to pre-market proof of safety or efficacy. Even though a healthy skin care regimen may incorporate cosmeceuticals, this article focuses on the two most effective evidence-based methods available to achieve and maintain healthy skin: sun protection and the use of topical prescription retinoids.
WHAT IS PHOTOAGING?
Lifelong exposure to solar radiation accelerates the skin’s intrinsic aging process and leads to photoaging, which is characterized by wrinkles, dyspigmentation, laxity, roughness, sallowness, and telangiectasias. Severe photodamage may cause actinic keratoses and cutaneous malignancies. Histologically, photodamaged skin shows keratinocytic and melanocytic atypia, loss of epidermal polarity, degeneration of collagen, deposition of abnormal elastic tissue, and tortuous microvasculature. Both ultraviolet (UV) B and UVA radiation are implicated in these changes. Smoking and environmental factors, such as wind and pollutants, also accelerate skin aging.
Sun protection starts with avoidance of peak solar radiation, which occurs between 10:00 AM and 2:00 PM. Modifying outdoor behavior and wearing sun-protective clothing are more effective preventive measures than using sunscreen. Hats also play an important role when sun exposure is unavoidable. Although baseball hats may be in vogue, they protect only the forehead and nose, leaving the cheeks, chin, and neck exposed. For total facial protection, the best hat is one with a brim that is at least 7 cm wide.
The FDA-approved technique for assessing the efficacy of sunscreens and sun-protective clothing yields a number called the sun protection factor (SPF) rating. The SPF rating is calculated by comparing the amount of time necessary to produce sunburn on protected skin to the amount of time necessary to cause the same reaction on unprotected skin. For example, if a burn normally requires 10 minutes of midday sun exposure, a sunscreen with SPF 15 will prolong this time by a factor of 15, thereby rendering protection for 150 minutes. The SPF determination applies to UVB radiation only.
Normal clothing may provide SPF ratings between 6 and 15, which drops below a rating of 5 once the fabric becomes wet. Sun-protective clothing products such as Solumbra, and fabrics made of Solarweave or treated with SunGuard, offer SPF 30 or higher. Although there are assays for protection against UVA, none is universally accepted. Therefore, sunscreens in the U.S. often are not labeled for their ability to block UVA.
To be maximally effective, sunscreens should block both UVB and UVA radiation. Traditional UVB blockers include para-aminobenzoic acid (PABA), salicylates, and cinnamates. Benzophenones (e.g., oxybenzone) block both UVB and UVA radiation, while dibenzoylmethanes (e.g., avobenzone, also known as Parsol 1789) block UVA radiation only. Avobenzone is capable of a high degree of UVA absorption, but, ironically, it is unstable in sunlight. Physical blocking agents such as zinc oxide and titanium dioxide are composed of particles that scatter, reflect, or absorb both UVB and UVA radiation. Older physical blockers were opaque and left a white film on the skin, but newer micronized preparations provide broad-spectrum protection without the residue.
The newest generation of sunscreens addresses the need for broad-spectrum protection, stabilization of active ingredients, and cosmetically appealing formulations. The technologies Mexoryl and Helioplex add a chemical to produce photostable avobenzone combined with conventional UVB filters. These provide 5 hours of UVA protection.3 Dermaplex, another emerging technology, requires fewer chemical sunscreens to provide UVB protection as well as photostable UVA protection.4
Patient education about proper sunscreen application is paramount. SPF measurement is based on sunscreen applied at a concentration of 2 mg/cm2. Studies show that most people apply a layer as thin as 0.5 mg/cm2, resulting in an SPF significantly lower than stated on the label. Sunscreen should be applied to the face every morning, whether it is sunny or overcast, as follows: After washing the face, apply a thin layer of sunscreen or daily moisturizer with an SPF and allow it to dry; then follow with a second layer. Sunscreen application should be repeated every 4 hours and immediately after excessive perspiration and swimming.
TOPICAL PRESCRIPTION RETINOIDS
For more than 20 years, topical prescription retinoids have been recognized for their efficacy in reversing the signs of photoaging. Topical retinoids approved by the FDA for treating photodamaged skin include tretinoin 0.02% and 0.05% emollient cream and tazarotene 0.1% cream. Other formulations and retinoid analogues, such as adapalene, are used off-label. Topical retinoids are not recommended during pregnancy and lactation and should be discontinued in women who are pregnant or are trying to conceive.
Tretinoin is the most well-studied topical prescription retinoid. It improves both the clinical and histologic signs of photoaging. Reduction of fine wrinkles, mottled hyperpigmentation, and roughness occur as soon as 2 weeks after initiation of treatment. These effects can be sustained with continued use. Histologically, long-term treatment (mean duration, 2.3 years) with topical tretinoin 0.05% emollient has been shown to reduce epidermal cellular atypia and thicken the collagen band in the papillary dermis.
Tazarotene 0.1% cream achieves similar success in reversing the signs of photoaging. Compared with nonmedicated vehicle, tazarotene significantly improved fine wrinkling and mottled hyperpigmentation after 24 weeks of once-daily application. Clinical improvement did not plateau by week 52, suggesting that additional improvements may be gained with longer treatment.
Skin irritation is the most common side effect of topical retinoid use. Desquamation, erythema, and stinging generally occur when treatment is first initiated and are usually transient. Irritation can be ameliorated by short contact or alternate-day application and by avoiding abrasive cleansers. Patient education regarding the proper use of topical retinoids cannot be overemphasized: At night, after washing the face and patting it dry, apply a pea-sized amount sparingly over the entire face, being careful to avoid delicate areas around the eyes, nose, and mouth. In addition, a daily moisturizer with sunscreen is recommended.
Despite the myriad of skin products claiming to "turn back the clock," the most effective evidence-based approach to photoaged skin is a combination of sun protection and topical prescription retinoids. Proper skin care serves as a foundation for more invasive office procedures such as botulinum toxin to smooth dynamic wrinkles, dermal fillers to soften the appearance of creases and folds, and resurfacing lasers and light sources to improve dyspigmentation and texture. Given recent advances in sunscreen technology and retinoid options, women can adopt healthy skin practices for the prevention and treatment of photoaging more easily than ever.