7.2 Active Ingredients: AHAs, BHAs, Enzymes & Retinoids

Active Ingredients: AHAs, BHAs, Enzymes & Retinoids

Introduction to Active Exfoliants and Cell Communicators

In professional skin care, active ingredients are the powerhouse components that create visible, structural changes in the skin. Among the most widely utilized and effective actives in an esthetician's arsenal are chemical exfoliants—such as Alpha Hydroxy Acids (AHAs), Beta Hydroxy Acids (BHAs), and botanical enzymes—as well as powerful cell-communicating retinoids. Understanding the specific mechanisms of action, appropriate indications, and strict contraindications for these ingredients is mandatory for safe and effective practice under Tennessee state standards.

Alpha Hydroxy Acids (AHAs)

Alpha Hydroxy Acids are a group of water-soluble acids derived from sugary fruits, milk, and nuts. They work primarily by breaking down the desmosomes (the protein bonds or "cellular glue") that hold dead skin cells together in the stratum corneum. This process accelerates cellular turnover, revealing smoother, brighter skin.

Common AHAs in Esthetics

• Glycolic Acid: Derived from sugar cane, glycolic acid has the smallest molecular weight of all AHAs. This allows for rapid and deep penetration, making it highly effective for treating hyperpigmentation, fine lines, and textural irregularities. However, its rapid penetration also means it has the highest potential for irritation.
• Lactic Acid: Derived from sour milk, lactic acid has a larger molecule than glycolic acid, leading to a slower, gentler penetration. It is uniquely hydrating, as it stimulates the production of natural moisturizing factors (NMFs) and ceramides in the skin. It is ideal for dry, sensitive, or hyperpigmentation-prone skin.
• Mandelic Acid: Extracted from bitter almonds, mandelic acid has one of the largest AHA molecules. It penetrates very slowly and is well-tolerated by sensitive skin types, including rosacea-prone skin. It also exhibits mild antibacterial properties, making it beneficial for adult acne.
• Malic Acid (apples), Tartaric Acid (grapes), and Citric Acid (citrus fruits): These are often used as booster acids in formulations to enhance the effects of glycolic or lactic acids, and to help adjust the product's overall pH.

Beta Hydroxy Acid (BHA)

The primary Beta Hydroxy Acid used in skincare is Salicylic Acid, typically derived from willow bark, sweet birch, or wintergreen.

Mechanism of Action

Unlike water-soluble AHAs, salicylic acid is lipid-soluble (oil-soluble). This critical difference allows BHA to penetrate through the sebum in the sebaceous follicles, exfoliating the pore lining from the inside out.

Indications for Use

Because of its lipophilic nature and its inherent anti-inflammatory and antibacterial properties, salicylic acid is the gold standard for treating oily, congested, and acne-prone skin. It dissolves impactions (comedones) and helps regulate sebum production. Under Tennessee state guidelines, estheticians must be extremely cautious with the concentration and pH of chemical peels to ensure they do not exceed the scope of practice, which limits exfoliation to the epidermal layers.

Plant Enzymes

For clients who cannot tolerate the acidity of AHAs or BHAs, botanical enzymes offer a gentle alternative. Enzymes are proteolytic, meaning they work by digesting the keratin protein in dead skin cells on the surface.

Common Enzymatic Agents

• Papain: Sourced from papaya, this enzyme is widely used for its gentle but effective protein-dissolving capabilities.
• Bromelain: Derived from pineapple, bromelain is highly effective at smoothing the skin and possesses mild anti-inflammatory properties.
• Pumpkin Extract: Rich in vitamins A and C, pumpkin enzymes provide both exfoliation and antioxidant benefits, leaving the skin glowing without harsh peeling.

Enzymes only digest dead tissue and stop working once the dead cells are removed, making them one of the safest exfoliation methods for highly reactive or compromised skin.

Retinoids (Vitamin A Derivatives)

Retinoids encompass a family of Vitamin A derivatives that are arguably the most extensively researched ingredients for anti-aging and acne treatment. They function as cell-communicating ingredients, meaning they connect to receptor sites on the skin cells and instruct them to behave like younger, healthier cells.

Types of Retinoids

• Retinoic Acid (Tretinoin): This is the active, prescription-only form of Vitamin A. It binds directly to cellular receptors to speed up cell turnover, stimulate collagen synthesis, and normalize follicular keratinization. Because it is highly potent, it often causes retinoid dermatitis (redness, flaking, and irritation) during the initial acclimation phase.
• Retinol: An over-the-counter derivative that must be converted by the skin's enzymes into retinoic acid before it can be used. This conversion process makes it less potent but significantly less irritating than prescription tretinoin.
• Retinyl Palmitate: An ester of Vitamin A, this is the weakest, most stable, and least irritating retinoid. It requires multiple enzymatic conversions to become active, making it suitable for very sensitive skin, though results take much longer to appear.

Depth of Exfoliation and Collagen Stimulation

While AHAs and BHAs exfoliate from the top down, retinoids work from the bottom up. They stimulate the basal layer to produce new cells at a rapid rate, which eventually pushes the older cells to the surface to be shed. Furthermore, retinoids stimulate fibroblasts in the dermis to produce new collagen and elastin, structurally thickening the dermal layer while compacting the stratum corneum.

Contraindications and Safety Protocols

The use of potent active ingredients requires strict adherence to safety protocols.

• Contraindications: Clients currently using prescription isotretinoin (Accutane) must avoid all chemical exfoliants and retinoids for at least six months post-treatment. Active herpes simplex lesions, sunburns, open wounds, and recent laser resurfacing are absolute contraindications.
• Pregnancy: Salicylic acid and all forms of retinoids are generally contraindicated during pregnancy and lactation.
• Sun Sensitivity: AHAs and retinoids cause photosensitivity. Estheticians must mandate the daily use of broad-spectrum sunscreen for any client using these ingredients. Failure to observe these guidelines violates Tennessee state board safety standards and can result in severe skin damage and liability.