Chemical peels complete guide

Chemical peels involve the use of chemical solutions to induce controlled destruction at specific levels of the skin. This leads to tissue regeneration and the sloughing of dead cells, thereby enhancing the skin health of the body and face.

Since 1950, chemical peels have been widely used in dermatology. Over time, this treatment has evolved greatly, with the advent of newer technologies such as alpha hydroxy acids (AHAs) and trichloroacetic acid (TCA), which are designed to penetrate different depths of the skin. In this article, we will outline the properties of various deep and medium chemical peels.

Classification of chemical peels

The classification of chemical peels is currently based on their depth of penetration. Deep chemical peels are able to penetrate into the reticular dermis, while medium peels can penetrate into the papillary dermis. In contrast, superficial chemical peels are able to penetrate into any depth of the skin in the epidermal layer, including the stratum basale. There is a subtype of superficial peels known as very superficial peels, which only affect the stratum corneum.

The depth of penetration is not dictated by the type of peeling solution alone. A number of other factors can determine how deep into the skin the peel will go, including the method of application, skin condition, duration of application, availability of free acid, pH level, and concentration of the peeling solution. For instance, when left on the skin for 5 minutes, a 70% glycolic acid solution can be used as a superficial peel. However, when applied for 15 minutes, it causes a peeling effect similar to that of a medium peel.

Preparing for the peeling procedure

Before receiving the treatment, patients should practice a skin preparation regime. This allows for a more efficacious rejuvenation and reduces the risk of harmful sequelae (e.g. post-inflammatory hyperpigmentation or PIH). Typically, this consists of a skin-lightening agent (e.g. kojic acid and hydroquinone), isotretinoin or retinol, and a low concentration alpha hydroxy acid moisturizer or cleanser. A sunscreen is often included to reduce the excitability of melanocytes. Patients should begin preparation at least 2 weeks before the skin peeling treatment. 

Medium chemical peels

Medium peels are used to manage superficial atrophic scars, pigmentary disorders, and wrinkles caused by photoaging. Conventionally, a 40% or 60% TCA solution is used as a medium peeling agent. While highly effective, it is associated with a high risk of complications, such as pigmentation and scarring. Nowadays, 35% TCA solutions are often used in combination with solid carbon dioxide, 70% glycolic acid, and Jessner’s solution to produce similar results with less adverse effects. The results are comparable to that of a 50% TCA peeling solution, but with a lower risk of complications.

Mechanism of action

TCA is a protein denaturant. As a water-soluble compound, it is unable to penetrate into the sebaceous skin (which is rich in lipids). Therefore, it is important to precondition the skin and use superficial peeling before applying TCA. This thins the stratum corneum, helping to increase its permeability and eliminate sebum from the skin’s surface. As a result, the penetration is more even and deeper. Additionally, the depth of protein denaturation will be more consistent and uniform.


The treated skin may be swollen right after using a medium chemical peel. The patient may also experience tightness in the skin. Some dermatologists may recommend applying occlusive ointments for symptomatic relief. Usually, the ointments are applied a few times a day. This method is known to reduce recovery time and the risk of persistent erythema after the procedure.

From the third day onwards, separation of the epidermis from the underlying skin can be observed. The skin peeling usually begins at the perioral area, eventually spreading to the entire face and the forehead. It is not advisable to scratch or pick the epidermis, as scarring may occur. Nevertheless, the dead skin layer can be trimmed using a pair of sharp scissors. It is recommended to use a moisturizer after 5 days. The process of skin peeling may persist for up to 10 days.

The new skin will appear dramatically brighter and more even after the clearance of the epidermal peel layer. Aside from that, wrinkles and fine lines will become less visible. The appearance of blemishes and pigmentation is also minimized. At the same time, the dermis layer is gradually remodeled, eventually leading to neocollagenesis in 6 weeks. This helps to consistently improve the quality of the skin. Further treatments can be carried out for skin rejuvenation, depending on the severity of aging and sun damage. The pretreatment regime can be reinitiated after 3 weeks.

Deep chemical peels

Deep peels usually involve the use of phenol. While TCA solutions of more than 50% have been traditionally used, they are associated with a high risk of complications. Therefore, phenol is more widely used due to its better safety profile.

Mechanism of action

Similar to TCA, phenol penetrates into the skin to induce protein coagulation and denaturation. This occurs at a specific level of the dermal layer. In contrast to TCA solutions, phenol (sometimes referred to as a “quick peel”) is able to rapidly penetrate deep into the reticular dermis of the skin.

Deep chemical peels are generally indicated for moderate to severe acne scars, dyschromias, and wrinkles. Through epidermolysis (in which the papillary dermis is involved), deep peels deliver significantly superior results to medium peeling agents, dramatically improving pigmentation and rhytids.

Deep phenol peel

Phenol deep peeling is inherently more risky than medium peels. Due to the greater depth of dermal injury, phenol deep peeling is associated with an increased risk of hypopigmentation, PIH, delayed healing and scarring. Additionally, because it is cardiotoxic and absorbed systematically, phenol peeling can potentially cause heart failure. The degree of risk depends on the volume of phenol used.

As such, a complete facial treatment should be carried out section by section (i.e. one area should be completed before treating the next). It is recommended to perform cardiac monitoring in a clinical environment. During the peeling treatment, it is recommended to administer steroids orally.

Occasionally carried out under general anesthesia, phenol deep peeling may cause extreme discomfort. An intravenous or oral sedative should be administered before, during, and after the procedure. As with medium peels, the skin should be thoroughly degreased and cleansed prior to the treatment. Then, apply the phenol solution to the predetermined area with rung and rolled gauzes. After treating the first area, proceed to the next area. The end point is reached when a grey-white frost of coagulated protein (and the associated loss of erythema) are observed. When there is a loss of erythema, the peel has progressed beyond the vascular loops in the papillary dermis.


Due to its deeper depth of penetration, the recovery time for phenol deep peeling is generally longer. Waterproof tape masks or other occlusive dressings should be used for the first 2 days. At this point, the skin is exudative and wet. Therefore, careful wound care is required. Thymol iodide should be applied a few times a day for 1 week. Movement may cause the healing wound in the perioral area to crack, especially during the 1st week. Patients should limit the movement of the mouth (e.g. ingest blended meals using a straw). By day 9, epidermal re-epithelialisation will occur.

The new skin may appear swollen and erythematous. For peels that are very deep, these symptoms may last for 4 weeks. Phenol deep peels are designed to deliver durable results, dramatically improving pigmentation, texture, and rhytids on the face.

Complications related to chemical peeling

While producing exceptional results, chemical peels can result in a number of complications. To minimize the risk of complications, practitioners should carefully select the patients and determine the most appropriate peel. In addition, it is essential to observe the endpoints closely and carry out a pretreatment regime..

Common side effects such as erythema are self-limiting and will resolve themselves 3 to 4 weeks after a medium peel. Persistent erythema may indicate an inadvertent deeper depth of peel, prior skin diseases such as eczema or rosacea, and contact sensitization. Herpetic lesions are commonly observed after the peeling procedure, especially in patients who have previously had herpetic lesions. For patients who are susceptible to herpetic lesions, prescribe an antiviral prophylaxis as needed. Antiviral medications may be prescribed routinely to all individuals who undergo chemical peelings..

While relatively uncommon, patients may experience scarring a few months after undergoing a medium peel. Early symptoms of scarring include prolonged and intense induration and erythema. Prompt and early treatments using topical steroids may help to relieve the symptoms. Infections due to medium chemical peeling are not common. They usually cause symptoms such as greater-than-expected pain, excessive crusting, pustules and erythema..

Virology, mycology and bacteriology swabs should be collected and depending on the lab results, empirical treatment may be started. A potential complication of deep chemical peeling is permanent hypopigmentation, which tends to be more common in dark-skinned patients. This may occur as a result of an infection or other complications during the recovery period. Deep peels also have a risk of causing PIH. Patients who currently have pigmentation issues are at a higher risk of developing this condition. Fortunately, adequate preparation prior to the peeling may help to reduce the risk. If PIH does occur, use topical 4% hydroquinone for management.

Before treatment, identify all risk factors for peeling-related complications. Patients who have a high risk of developing undesirable effects should be advised against undergoing the procedure. Examples of risk factors are immunocompromised status, inadequately controlled diabetes, and smoking. Patients who have had laser skin resurfacing or a recent facelift should refrain from receiving this treatment. Similarly, patients who have a medical history of keloid or hypertrophic scarring and herpes simplex infections should not receive chemical peels. Do not perform chemical peels on patients who have used isotretinoin in the past 6 to 12 months, as they are more likely to develop scarring.


When selecting a chemical peel treatment, take into account the potential risks and benefits of each specific product. For example, using phenol deep peeling may be justified if its potential benefits outweigh its risks. Additionally, the experience of the practitioner should be taken into consideration during the selection process. Experienced practitioners who have carried out hundreds of deep peeling procedures may be able to achieve better results with fewer complications. .

Furthermore, to ensure the success of the treatment, practitioners should learn about the anatomy and physiology of the skin and the mechanism of action of different chemical peels. This will increase patient comfort, safety, and satisfaction.