The prime use of a moisturizer is to restore the low moisture content of the skin, low moisturize in the skin is a prime factor in dry skin conditions.

Mechanism of Action of Moisturizers

There are many moisturizers on the market but they all have the same goal: to increase water content in the upper layers of the skin. Increasing the skin’s ability to hold onto water is another strategy for moisturizing skin. Increasing levels of natural moisturizing factor (NMF), glycerin (glycerol), and other humectants such as hyaluronic acid will help skin hold onto water.

Occlusives Agents

Occlusive coat the skin to reduce Trans epidermal water loss (TEWL). An occlusive is one of the best choices to treat dry skin because it provides an emollient effect as well as decrease TEWL.

• Petrolatum

  Petrolatum is considered one of the best moisturizers. Petrolatum is also well known for being non comedogenic. Many find the greasy, oily texture cosmetically inelegant. Petrolatum is often combined with other ingredients to minimize the greasy feeling.

• Lanolin

  Lanolin is a complex natural product used for skin hydration.

• Oils

  Essential oils are now commonly used in moisturizing products or as moisturizing agents themselves.

• Mineral Oil

  Mineral oil is one of the most frequently used oils in skin care products. In 2004, a randomized, double-blind, and controlled trial showed that mineral oil and extra virgin coconut oil were equally efficacious and safe as moisturizers, in treating mild-to-moderate dryness. In 34 patients, with surface lipid level and skin hydration significantly enhanced in both groups.

• Natural Oils

  Natural oils contain fatty acids that are important in maintaining the skin barrier. Linoleic acid, an omega-6 fatty acid present in sunflower, safflower, and other oils, is an example of an essential fatty acid that must be obtained from the diet or through topical applications.

Sunflower Seed Oil

The primary constituents of sunflower oil, oleic and linoleic acids are fatty acids that provide particular benefits to the skin. In a study Intended to identify Safe and inexpensive vegetable oils that are effective in enhancing epidermal barrier function and available in developing countries, Mustard, olive, and soybean oils significantly delayed recovery compared to controls or skin treated with Aquaphor, which is used to ameliorate skin barrier functions. One application of sunflower seed oil significantly accelerated skin barrier function recovery within an hour of application. More recently, some of the same investigators compared the effect of the topically applied emollients sunflower seed oil and Aquaphor in the prevention of skin infections.

EVENING Primrose Oil

Evening primrose oil (EPO) is rich in omega-6 fatty acids, containing both linoleic and y-linoleic acids. Linoleic acid, which helps to maintain skin cells cohesion and contributes to TEWL reduction, is used by the body to produce moisturizing factors. The presence of linoleic and y-linoleic acids justifies the use of EPO in patients with dry skin or poor nutrition.

Olive Oil

Olive oil used for bathing as well as medicinal purposes, olive oil contains various potent compounds, many with antioxidant properties.

Jojoba

Jojoba oil is derived from the cold-pressed peanut-or small olive-sized seeds of the jojoba plant and contain several fatty acids. Jojoba oil is similar in consistency with human sebum. Consequently considered to be a natural moisturizer, jojoba oil, which is typically used as a humectant, has been found to exhibit significant beneficial properties as an analgesic, antibacterial, anti-inflammatory, antioxidant, antiparasitic, and antipyretic agent.

Humectants

Humectants are water soluble materials with high water absorption capabilities. They have the capacity to attract water from the atmosphere (if atmospheric humidity is greater than 80%) and from the underlying epidermis. Although humectants may draw water from the environment to help hydrate the skin, in low-humidity conditions they may take water from the deeper epidermis and dermis resulting in increased skin dryness. Some humectants have bacteriostatic activity as well. Humectants draw water into skin, causing a slight swelling of the upper layers of skin that gives perception of smoother skin with fewer wrinkles. As a result, many moisturizer are touted they impart no long-term anti wrinkling effect.

• Glycerin

  Glycerin (glycerol) is a strong humectant and has a hygroscopic ability that closely resembles that of NMF (natural moisturizing factor). This also allows the Skin to retain high water content even in a dry environment and rapidly restores dry skin to normal hydration. They also help prevent the return to dryness for a longer period than the other formulations, even those containing petrolatum. Glycerin causes an expansion of the upper layers of skin because of increased thickness of the cells. Glycerin appears to create a reservoir of moisture-holding ability that renders the skin more resistant to drying.

• Urea

  Urea is a component of the skin. It has been used in hand creams since the 1940s. In addition to being a humectant, urea displays a mild anti itching effect.

• Hydroxy Acids

  Alpha Hydroxy acids (AHAs) are a family of naturally-occurring organic acids that function as humectants. Glycolic and Lactic acids are the most commonly used AHAs in moisturizing products. The cosmetic effects of Hydroxy acids include normalization of skin exfoliation and decreased formation of dry scales on the surface of the skin.

• Lactic Acid

  Lactic acid is unique because it is an AHA as well as a component of the NMF.

• Propylene Glycol

  Propylene glycol (PG) is an odorless liquid that functions as both a humectant and an occlusive. It displays antimicrobial and keratolytic activity. PG has shown to enhance the penetration of drugs such as minoxidil and steroids. Although PG is known to be weak sensitizer itself, it may contribute to contact dermatitis by enhancing penetration by other allergens.

Emollients

These are substances added to cosmetics to soften and smooth the skin. This leads to a smoother surface with less friction and greater light refraction

Oatmeal

Whole oat flour is thought to be protective in nature and to exhibit antioxidant activity and display a cleansing capacity. Another oat compound, oat beta-glucan, is believed to be immunomdulatory. Oat proteins exert various beneficial effects, including emulsifying activity, fat-binding activity, water-hydration capacity, low foaming potential, and antioxidant activity. Significantly, oatmeal has been shown to have moisturizing and anti-inflammatory properties. It gives preventive effect on skin irritation.

Shea Butter

Used widely in cosmetic products as a moisturizer, particularly as an emollient, shea butter is a natural fat derived from the shea or karate tree. Recent work has revealed that shea butter manifests anti-inflammatory activity. Shea butter is included and touted in various skin and hair care products, especially high-end skin products, for conferring rich emollient benefits, and is thought to maintain moisture and to provide benefits as an adjuvant moisturizer in the treatment of skin conditions such as atopic dermatitis, dry skin, acne, scars, and striae alba.

OTHER INGREDIENTS

Many moisturizers contain antioxidants such as vitamins C and E, coffeberry, green tea, and coenzyme Q10. Niacinamide and soy are also popular additives in cosmetic moisturizer. Copper peptide has been widely used for several years to enhance wound healing. Although some clinical trials have reported improvement of fine line and wrinkles with topical use of products containing copper peptide, more research is warranted to determine the efficacy of copper peptide as an antiaging agent.

Summary

While the ultimate purpose of all moisturizers is to enhance the hydration state of the Skin, moisturizing ingredients operate in distinctly specific ways. Occlusive coat the Skin and reduce TEWL; humectants attract water from the atmosphere and from the underlying epidermis, hydrating the skin; and emollients soften and smooth the skin.