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After undergoing aesthetic medical procedures such as photon therapy, matrix RF, hydra-facial, and minimally invasive treatments, the skin’s barrier will be temporarily compromised, exposing the epidermal nerves and making the skin highly sensitive and fragile. If normal daily skincare products are used, it can easily lead to burning sensations, redness, and dryness, prolonging the recovery period of the skin. This article explains the need to avoid fragrances and ordinary preservatives in post-operative care based on skin condition and the principles of ingredient stimulation. The differences between post-aesthetic medical skin and healthy skin are significant. Healthy skin possesses a complete barrier formed by keratinocytes, intercellular lipids, and the sebum film, which can block most small irritating molecules from penetrating the dermis. However, aesthetic medical procedures such as phototherapy, microneedling, and chemical peels can damage the structure of the stratum corneum: – Keratinocytes become loose, and intercellular gaps widen; – The surface sebum film is damaged, reducing moisture retention; – Superficial nerves in the dermis become more susceptible to stimulation; – The activity of skin inflammatory cells increases, leading to discomfort from minor external irritations. In simple terms, post-operative skin lacks a protective buffering layer, making it easy for external substances to reach the dermis directly, significantly increasing the risk of irritation. Comparison of healthy barrier and the damaged barrier structure after aesthetic procedures. Fragrance is a major potential irritant for post-operative skin. 1. Irritation Mechanism Fragrances in skincare products are divided into synthetic fragrances and essential oils. Among them, aldehydes and phenolic compounds have small molecular sizes and strong permeability. Healthy skin barriers can block most fragrances, with only a few sensitive skin types experiencing discomfort; however, damaged skin cannot block fragrances, which can penetrate directly through the stratum corneum, prompting immune cells to release inflammatory mediators, exacerbating redness, warmth, and itching. Clinically, the probability of fragrance-induced contact dermatitis significantly increases when the barrier is damaged. 2. Components to Avoid Ingredients labeled as “fragrance” or “aroma,” or various plant essential oils such as rose and citrus, are considered fragrance additives. Even if labeled as naturally extracted, there is still a risk of irritation during the post-operative healing phase, so it is advisable to avoid them as much as possible. 3. Adverse Effects Short-term use can easily lead to stinging and facial redness and burning; prolonged exposure to irritation can delay skin healing and also increase the likelihood of post-inflammatory hyperpigmentation. Illustration of fragrance irritation on skin. The compliance of preservatives does not mean they are suitable for damaged wounds; scenarios must be differentiated. 1. Normal function of preservatives Preservatives that comply with national cosmetics safety regulations have lower irritation under normal use on healthy skin and compliant concentrations. Their main role is to inhibit microorganisms within the bottle, ensuring that skincare products do not spoil easily after opening. 2. Reasons for caution with damaged skin post-surgery First, nerve stimulation: Most low-molecular-weight preservatives can penetrate damaged keratin and contact dermal nerves, causing stinging and itching, which hinders the self-repair of keratinocytes. Second, risk of wound infection: Microneedling and broken skin procedures can create tiny wounds. Ordinary cosmetics typically come in re-openable packaging; preservatives can only inhibit bacteria inside the bottle, unable to isolate external pathogens introduced during use, which can worsen wound discomfort. Third, delayed self-healing: Skin repair requires a gentle and stable environment. Prolonged exposure to preservatives can lead to low-grade inflammation, slowing down keratin regeneration and extending the recovery time for dryness and redness. 3. Advantages of medical dressings with preservatives Registered Class II medical repair dressings use independent disposable sterile packaging, produced to high cleanliness standards. They can be used once without the addition of traditional preservatives, minimizing microbial irritation and making them suitable for short-term wound care. Possible skin discomforts: – Immediate reactions: persistent stinging, facial warmth, widespread redness; – Short-term symptoms: recurrent dryness and itching, peeling, tightness that is hard to relieve; – Recovery period issues: slow resolution of inflammation, dull skin tone, increased risk of pigmentation; – Skin lesions: redness and swelling at the site of micro-injury, intensified discomfort. If any of the above occur, discontinue use of the product immediately, reduce external irritants, and consult a dermatologist promptly. Three Key Selection Criteria for Postoperative Repair Products 1. Simplified Formulation with Minimal Additives Prioritize products that focus on core ingredients for repair and hydration, avoiding irrelevant additives such as fragrances and colorants to reduce the burden on the skin. 2. Differentiate Cosmetic Products from Medical Dressings Based on Wound Type For intact skin with no damage: compliant cosmetic skincare products can be used normally. After procedures involving light therapy, microneedling, or skin tearing (where wounds and barrier damage are present): follow the doctor’s advice to use Class II medical dressings. The sterilization standards for cosmetic products are lower than those for medical devices and are not recommended for fresh wounds. 3. Prefer Individually Sterile Packaging Large-capacity bottles that are repeatedly opened can breed bacteria despite the presence of preservatives; individually sealed sterile packaging is more suitable for fragile post-surgical skin. Under a complete skin barrier, the fragrances and preservatives in regular skincare products typically do not cause significant irritation. However, skin that has undergone cosmetic procedures often has open wounds and compromised stratum corneum, greatly reducing its protective ability: fragrances can easily trigger allergic inflammation, and ordinary preservatives may continuously irritate the wound and interfere with skin self-healing. The core of postoperative repair is to create a low-irritation, clean, and gentle repair environment for the skin, minimizing interference from excessive additives to allow normal repair and regeneration of the stratum corneum and dermal tissue. *Note: This article is for educational purposes regarding skincare ingredients and does not substitute for professional medical advice. Please follow the guidance of the operating physician for specific postoperative care; read the product instructions for medical dressings or purchase and use them under medical supervision.    

In life, it’s inevitable to have some small accidents—like cutting yourself while chopping vegetables, falling off a bike, or popping a pimple… After the wound heals, many people wonder: why do some recover smoothly while others are left with noticeable marks? To answer this question, we need to start from the moment the wound forms, delving into the deeper layers of the skin to explore the repair process involving fibroblasts, the extracellular matrix (ECM), and the inflammatory response. Four Stages of Skin Repair: A Precise Relay After skin injury, the stages of hemostasis, inflammation, repair, and remodeling unfold in sequence. Step 1: Hemostasis – A few minutes after the injury, platelets gather and release signaling molecules that activate the clotting response, converting fibrinogen into fibrin to form a temporary “scaffold” that prevents blood loss and provides a landing point for subsequent cell migration. Step 2: Inflammation – About 2 hours later, neutrophils and macrophages arrive to clear bacteria and debris, releasing signaling molecules. Inflammation needs to be moderate; excessive or prolonged inflammation can lead to more pronounced scarring. Step 3: Repair – Fibroblasts are activated and differentiate into myofibroblasts, secreting large amounts of collagen (types I and III) and ECM proteins while also contracting the edges of the wound. New capillaries grow in, forming granulation tissue. Step 4: Remodeling – This stage can last from several weeks to months. Myofibroblasts secrete enzymes to organize the collagen, degrading the excess while retaining the orderly arrangement, ultimately leading to cross-linking and stabilization. The appearance of the healed area is essentially determined at this stage. Adult vs. Fetus: Why Do Fetal Healing Scars Appear Lighter? When injured similarly, fetal skin heals with lighter scars, while adults are more likely to leave marks. Research reveals several key differences: 1. ECM Hardness The extracellular matrix (ECM) in fetuses is softer than in adults, allowing fibroblasts to remain “calm” and be less prone to excessive activation. The harder ECM in adults makes cells more sensitive to mechanical stress, leading to increased collagen secretion, which may result in excessive deposition. 2. Different Ratios of TGF-β Subtypes There are three subtypes of TGF-β (Transforming Growth Factor-β): TGF-β1 and TGF-β2 promote fibroblast activation and are involved in fibrosis; TGF-β3 tends to inhibit excessive activation and promotes healing that is closer to normal skin. Fetal wounds have higher expression of TGF-β3, while adults predominantly express TGF-β1 and TGF-β2. This difference in ratios affects the quality of healing. 3. Different Polarization States of Macrophages Macrophages exist in two states: pro-inflammatory (M1) which release inflammatory factors, and anti-inflammatory/repair (M2) which release anti-inflammatory factors and participate in repair. Fetal wounds are primarily M2, while adults have a dominant M1 response initially, which lasts longer, continuously stimulating fibroblasts and potentially leading to excessive collagen deposition. Molecular mechanisms of scar formation Fibroblasts → Myofibroblasts Myofibroblasts are key executors of scar formation, expressing α-SMA which provides contractile ability, and secreting a large amount of collagen. Upon activation, the stiffer ECM promotes further differentiation of fibroblasts, making the ECM even harder, creating a positive feedback loop. Integrins – the “mechanical sensors” of cells Integrins are transmembrane receptors on the surface of fibroblasts that convert physical signals from the ECM into intracellular signals. Different integrins have different functions: αvβ6 activates TGF-β to promote fibrosis, α5β1 maintains homeostasis, and α1β1 binds to type III collagen, corresponding to the phenomenon of scar-free healing in fetuses. Collagen: An Important Component of Skin Structure Collagen accounts for more than 75% of the dry weight of the skin. Type I collagen provides strength and is the main type found in adult skin; type III collagen is finer and softer, and is present in higher amounts in fetal and young tissues. When the ratio of type III to type I is higher, the healed tissue is closer to the elasticity of normal tissue; when there is excessive deposition and disorganization of type I collagen, it is more prone to forming visible scars. Scientific Skincare: General Principles Supporting the Skin’s Self-Repair Based on the aforementioned mechanisms, daily care can refer to the following points: 1. Maintain appropriate hydration and softness of the skin—When the barrier is intact and adequately hydrated, the ECM environment is closer to a “soft” state, which is beneficial for fibroblast homeostasis. 2. Focus on collagen metabolism balance—The skin continuously synthesizes and degrades collagen. As mentioned earlier, the proportion of type III collagen has a direct impact on the quality of healing; thus, supplementing type III collagen in skincare helps provide more balanced collagen support for the skin. 3. Reduce excessive external stimuli—Factors such as ultraviolet rays, improper skincare, and mechanical friction may exacerbate local inflammation and affect the repair rhythm. 4. Choose gentle and reasonable skincare methods—Use products with mild formulations, avoid excessive exfoliation and aggressive squeezing, and allow the skin sufficient time for self-repair. The skin is the largest organ of the human body and serves as our most direct barrier against the outside world. Each time a small wound heals, it is a “project” involving the precise cooperation of cells, matrix, and signaling molecules. Understanding this is not to induce anxiety, but to cultivate greater respect for the wisdom of the skin, promoting rational approaches in daily skincare. Scientific skincare is the greatest respect for the skin’s inherent powers.