Skin resurfacing (medical peels)

This article explains, with the chemical peel at its centre, how to assess the changes described under the name "skin resurfacing". The research on pigmentation, acne scars and photoageing is dealt with separately; the difference from mechanical methods, the depth of the procedure, the burden of healing and the authorisation framework in Türkiye are examined together. The aim is not to choose a substance or a depth but to make it possible to understand which evidence a claim about a result rests on.

What are skin resurfacing and medical peels?

"Skin resurfacing" is not the name of a single procedure; chemical peels, mechanical resurfacing and other methods aim to produce a change in the skin by different routes.^1,2 In a chemical peel, controlled damage is produced in particular layers of the skin with a chemical substance; the depth aimed at is related to the skin problem being addressed and to the preparation used.³

Are a chemical peel and dermabrasion the same thing?

The effect of a chemical peel rests on the substance used, while in dermabrasion the surface of the skin is abraded mechanically; DermNet defines dermabrasion as a surgical resurfacing procedure.² Microdermabrasion is a more superficial abrasion and is not the same procedure as dermabrasion.² All of these names being mentioned under the heading "skin resurfacing" does not show that they have the same effect, the same healing or the same risk.^2,3

Dermabrasion is mentioned here to explain the boundary between methods. The results of the chemical peel research below should not be read as the results of mechanical methods. For the same reason, the microneedling used as a comparator in one acne scar study does not represent all mechanical resurfacing procedures.⁴

What do superficial, medium and deep mean?

This classification is not an order of quality but a description of the tissue layer aimed at; a superficial peel is limited to the epidermis, while medium and deep peels reach different levels of the dermis.³ The name of the substance does not on its own determine that depth; trichloroacetic acid (TCA), for example, has both superficial and medium-depth uses.⁵

Depth	Tissue level	Examples of substances and methods
Superficial	Epidermis	Glycolic acid, salicylic acid, some TCA applications and Jessner's solution used alone.3,5
Medium	Effect reaching the papillary and upper reticular dermis	TCA and some combined peels.3,5
Deep	Deeper level of the reticular dermis	Deep peels containing phenol.3,6

Jessner's is not the name of a single acid but a mixture; its use alone at a superficial level has to be distinguished from its use in combination with other substances to reach greater depth.⁵ The United States Food and Drug Administration (FDA) states that the concentration, the number of applications and the length of time the product is left on the skin all affect the depth of penetration.⁷ Knowing only the name of the acid, or a percentage on the packaging, is therefore not enough to understand the scope of the procedure.^3,7 The classification here is not a set of instructions; no contact time, number of coats or mixing directions are given.

Which changes are to be expected, and which are not?

Are pigmentation, acne scars and wrinkles the same target?

Different outcomes are measured in studies of melasma, atrophic acne scars and photoageing; a reduction in a pigment score, a change in the appearance of a scar and an increase in hydration measured by a device cannot be used in place of one another.^8-10 To understand the phrase "the skin was renewed", what changed has to be stated first.

In melasma, peels have been assessed as an addition to treatments directed at pigment; in the expert consensus, topical treatment is maintained as the basic approach.⁵ In acne scarring, the appearance and grade of the depression have been assessed; a reduction in active spots and an improvement in scars are different research questions.^3,9 A change reported for fine lines does not mean that deep furrows have disappeared either; DermNet states that a TCA peel has no effect on deep furrows.¹

What a procedure is directed at therefore matters as much as how that complaint was measured. In reading a "favourable" result, whether the measurement belongs to pigmentation, to hydration or to the appearance of a scar should not be overlooked. The studies below are presented separately in order to keep that distinction visible.

Where does the boundary with lasers, PRP and microneedling begin?

The laser and energy devices article deals with laser resurfacing and energy-based methods. The results of those methods are not added here to the evidence for chemical peels. The PRP, stem cell treatments and mesotherapy articles should likewise be read with their own scope and sources.

Microneedling appears in this article as the comparison arm of an acne scar study.⁴ The result of research in which other procedures are also present cannot be presented as the effect of only one of them; the combined applications in the photoageing review therefore also have to be separated from studies of peels alone.¹¹ Nor does appearing under the same "skin resurfacing" heading in a training programme make the methods the same procedure.¹²

What does the evidence on efficacy show?

What does adding a peel contribute in melasma?

The systematic review by Sarkar and Lakhani included 24 studies covering 1075 participants; 15 of these were reported as randomised and 9 as clinical or comparative studies.⁸ 8 of the studies had a split-face design, and study durations ranged from 8 to 36 weeks.⁸ The review reported favourable results with peels in the treatment of melasma; because of the differences between the methods, however, no meta-analysis was performed.⁸

That general favourable direction does not mean that adding a peel to another treatment provides additional benefit in every circumstance. In the 8-week split-face study by Hurley and colleagues of 21 Hispanic women, topical pigment treatment and sun protection were applied to both sides, and a glycolic acid peel was added to one side only.¹³ Improvement from baseline was seen on both sides, but no statistically significant additional difference was found in favour of the side to which the peel was added.¹³

It cannot be said here that the review and the single study give opposing answers to the same question. The review brings together different peels and comparisons, while the Hurley study tested the additional contribution to a particular basic treatment.^8,13 It is appropriate to read the finding neither as the ineffectiveness of all peels nor as firm equivalence between the two approaches; the study should be interpreted within its own comparison and its short assessment period.¹³

What outcome has been measured in acne scars?

Leheta and colleagues randomised 30 people with atrophic acne scars to groups receiving TCA CROSS and the needling method called percutaneous collagen induction.⁴ CROSS is a method in which the chemical substance is focused on the scars; it is not a synonym for a peel applied to the whole face.⁴ In the study record in the Cochrane review it is stated that, after 3 losses to follow-up in the peel group, 27 people remained in the analysis, that 12 of these were in the TCA CROSS group and 15 in the needling group, and that they were assessed 1 month after the final procedure.⁹

In the original study, improvement in the appearance of the scars was reported in both groups, and no significant difference was shown between the groups.⁴ Cochrane assessed the evidence for participant-reported improvement in this comparison as of very low certainty, and the evidence for the outcome of pigment darkening as of low certainty.⁹ "Low certainty" here does not mean that there was no improvement; it describes the limited confidence in an estimate reached with a small study, losses to follow-up and a short assessment period.⁹

A change in a scar is a favourable finding, but neither long-term persistence nor a method superior for everyone can be derived from this study.⁹ Comparing two active procedures is also not the same research question as measuring the effect against having no procedure at all. That distinction in particular prevents the sentence "no difference" from being read as "the two definitely give the same result".

What is known for photoageing and wrinkles?

The TCA review by Sitohang and colleagues examined 5 prospective studies, 3 randomised comparisons and 2 cohorts.¹¹ Favourable changes were reported in photoageing; the procedures performed alone and in combination, the comparators and the assessment criteria, however, differed.¹¹ The findings for hydration, elasticity, pigment and appearance were not calculated as a single "percentage of rejuvenation".¹¹

In a more recent randomised study, 46 postmenopausal women were divided into groups of 23 receiving a multi-component preparation containing TCA and a placebo; all the participants were Fitzpatrick skin type II.¹⁰ Because the preparation did not contain TCA alone, the result cannot be taken as the independent effect of a single substance.¹⁰ Significant results in favour of the preparation were reported at the hydration measurement points at 3 months, while no significant change was shown in the elasticity measurements.¹⁰

This result makes a benefit measured in terms of hydration visible; at the same time it prevents that increase in hydration from being widened into the disappearance of wrinkles or into the same effect in every skin type.¹⁰ 37 people attended the 3-month visit and missing data were imputed in the analysis; the 46 people at the start and the number attending every assessment are therefore not the same.¹⁰ A device measurement being favourable should not be reported on the assumption that the other measurements were favourable too.

How are authorisation and the suitability of the product assessed in Türkiye?

Are a certificate and a facility's authorisation the same thing?

How health services for aesthetic and cosmetic purposes are to be provided in private outpatient diagnosis and treatment facilities is governed by the Regulation on Private Health Facilities Providing Outpatient Diagnosis and Treatment, dated 19 April 2025.¹⁴

The provision in force requires three conditions together. Health services for aesthetic or cosmetic purposes may be provided within a medical centre, a polyclinic or a doctor's practice; within the competences physicians have acquired through their training curriculum or through a certificate; within the medical procedures permitted at the facility where they work; and provided that the physical space and minimum medical equipment defined for a polyclinic room are in place.¹⁴

The certificate referred to in the regulation is one registered under Ministry legislation.¹⁴ Types of peel and methods of application appear under the "Skin resurfacing" heading of the Ministry of Health's Standard for the Certified Training Programme in Aesthetic and Cosmetic Applications, dated 3 September 2025.¹² The 12 hours of theoretical and 11 hours of practical training given for that heading belong to the heading as a whole, which also covers PRP and other content, not to peels alone.¹² The presence of peeling solutions in the equipment list is likewise part of this training framework.¹²

The physician's competence and the facility's authorisation are separate things and both are required.¹⁴ A diploma alone, or any course certificate alone, does not show that all of these conditions are met. Nor is a training centre's authorisation to provide training the same thing as a physician's authorisation to carry out the procedure.^12,14

This provision covers private outpatient diagnosis and treatment facilities. A complete list of authorisation by profession and title, for every type of institution, cannot be derived from this text.¹⁴

Is a peeling product always a cosmetic product?

Example number 35 in the Turkish Medicines and Medical Devices Agency's guide on borderline products deals with products that remove cells or layers of cells from the surface of the skin by mechanical or chemical means.¹⁵ That distinction in the document is therefore not limited to chemical action; it is, however, a classification of products and does not by itself determine the legal class of every mechanical device.¹⁵

Products intended to remove dead cells or the upper layers of the stratum corneum, which do not significantly affect normal skin physiology and barrier function, may be regarded as cosmetic products.¹⁵ Products that expose the deeper layers of the stratum corneum, or that are intended to remove that layer entirely, cannot be regarded as cosmetic products because of their significant effect on the barrier and on physiology.¹⁵

The guide requires the final decision to be made on the basis of all the product's characteristics, its claims, the depth of peeling per application and the frequency of application.¹⁵ The word "superficial" in the clinical table does not on its own satisfy that legal assessment; the anatomical class of the procedure and whether the product counts as cosmetic are separate questions.^3,15 Falling outside the cosmetic class does not show that all preparations automatically fall into the same other class of product either; the example cited does not assign any such single class.¹⁵

A training document, a facility's authorisation to perform the procedure and the place of a particular product in the legislation therefore cannot be put in place of one another.^14,15 Being satisfied with the word "medical" on a product leaves these separate questions unanswered.

What are the risks and unwanted effects?

The American Academy of Dermatology (AAD) states that chemical peels have been used for more than 50 years and that, when performed by experienced physicians, side effects tend to be mild.¹⁶ That general frame cannot be used to count different depths or particular risks at the same frequency; the data on superficial procedures and on deep peels containing phenol are kept separate below.^6,17

The risk of colour change in darker skin

According to the AAD, people with darker skin tones can also have a peel; an assessment by a dermatologist experienced in those skin tones matters, however, and a lack of that experience can lead to permanent pigment problems.¹⁶ Darker skin is thus treated not as an automatic prohibition but as a characteristic that changes the assessment of risk.¹⁶ DermNet names the outcomes in which the risk rises: in Fitzpatrick skin types IV to VI the risk of dyspigmentation and of hypertrophic and keloid scarring is increased, and chemical peels must be performed cautiously and with the person's full informed consent.¹

In the records of superficial peels in the Fitzpatrick III-VI group by Vemula and colleagues, an unwanted event was reported in 18 of 473 procedures; the types reported most often are crusting, postinflammatory hyperpigmentation and erythema.¹⁷ The authors assessed the complication rate as relatively low and stated that the events reported resolved within 8 months.¹⁷ These records being collected over a 5-year period does not mean that each person was followed for 5 years; nor is the denominator people, it is procedures.¹⁷

For type VI, the adjusted odds ratio showing an association with any unwanted event was reported as 5.14, with a 95 per cent confidence interval of 1.21 to 21.8.¹⁷ This is not a rate belonging to the formation of pigmentation alone, nor directly 5.14 times a person's own risk; the wide confidence interval shows the uncertainty of the estimate.¹⁷ The study's favourable overall conclusion does not remove the difference by skin type in the same record.¹⁷

Scarring, infection and prolonged healing

Besides a change in pigment, prolonged redness, infection and the formation of scars are among the problems reported; depth, the characteristics of the skin and a previous history of healing affect the assessment.^1,18 Infection may be bacterial, fungal or viral; a history of cold sores therefore also matters in the assessment before the procedure.^1,18

Expected peeling and a permanent scar are not the same outcome; the AAD counts scarring among the unwanted effects that can occur rarely.¹⁶ Events having resolved in the Vemula series does not guarantee that no lasting problem will arise for every substance, every depth and every person; the series is limited to superficial procedures.¹⁷ The name of a risk should be read together with the procedure in which, and the follow-up over which, it was studied.

The systemic risk of deep peels containing phenol

In deep peels containing phenol the risk is not limited to the skin; systemic absorption and disturbances of heart rhythm are matters requiring particular assessment.⁶ DermNet states that phenol produces deep injury to the skin, that it is rarely used for facial peels nowadays because of the risk of scarring and because of its toxicity, and that its absorption through the skin can cause potentially fatal disturbances of heart rhythm and nerve damage.¹ The same source also writes that the method is very effective at improving both surface wrinkles and deep furrows; benefit and risk stand together.¹ The Landau series reported in the context of phenol peels in Marçon's review covers 181 women who had a full-face deep peel under cardiac monitoring.^6,19 Arrhythmia was reported in 12 people during the procedure; 4 events were self-limiting and 8 required treatment.¹⁹

The author reported the conclusion that the frequency of cardiac complications in an appropriately performed deep peel is lower than had previously been assumed.¹⁹ In the same series, diabetes, hypertension and depression were found more often in those in whom arrhythmia occurred; that observational association does not on its own show that these conditions cause arrhythmia.¹⁹ The result of this series under monitoring is not a guarantee for unsupervised use; nor should the risk belonging to phenol be generalised to all superficial peels.^6,19

How are healing and the duration of the result assessed?

The AAD states that most results are not permanent, because the skin continues to age.¹⁶ The completion of healing, the visit at which improvement was seen in a study, and the period over which an effect is retained are different measures of time. Putting one in place of another changes the meaning of the interval given.

Are the healing period and the effect lasting the same thing?

In the AAD's patient information, healing is given as 1 to 7 days for a superficial peel, 7 to 14 days for a medium peel and 14 to 21 days for a deep peel.¹⁶ These are the organisation's intervals for its depth groups; they are not a procedure or a return-to-work timetable assigned to the person reading this page.

The 8 weeks of the Hurley study is the study period; the visit 1 month after the final procedure in the Leheta comparison is a short-term outcome assessment; and Piejko's measurement at 3 months shows the state found at that visit.^9,10,13 These periods cannot be read as the pigmentation, the improvement in a scar or the change in hydration lasting that long. In the same way, a longer healing period is not numerical evidence of longer persistence; the studies presented here did not calculate any such relationship.^8,11

What matters in a dermatological assessment?

Skin type, the diagnosis of the pigmentation and the medical history

An assessment does not begin only with which acid will be chosen; the diagnosis of the pigmentation or the scar, the skin tone and any earlier pigment or scarring problems matter.^1,18 DermNet states that certain suspicious lesions should be examined separately and, where necessary, assessed with a biopsy; not every change in colour can be treated as a cosmetic mark.¹

In the preparation consultation, the AAD recommends discussing the medicines and supplements used, a history of isotretinoin, cold sores, scarring easily and previous cosmetic procedures.¹⁸ These subjects being asked about does not mean that the same prohibition or the same waiting period applies to all of them. What is reported in this article is the assessment framework the sources give; no personal instruction to stop a medicine and no preparation prescription is given.

Seeing in whom the research was carried out also helps an assessment. A hydration measurement in women who were all Fitzpatrick type II, for example, does not answer the question of safety in darker skin; nor does a record of superficial procedures in darker skin explain the cardiac risk of a deep peel containing phenol.^6,10,17 Reading the limit of the sample alongside a source's favourable finding places the result correctly without diminishing it unnecessarily.

Sun protection and assessment after the procedure

The AAD reports daily use of sunscreen after healing for a superficial peel, total avoidance of the sun until the skin heals for a medium peel, and total avoidance for 3 to 6 months for a deep peel.¹⁶ That difference shows that a decision about depth relates not only to the possible change but also to the burden of protection afterwards.¹⁶

The organisation's periods are not combined here into personal care instructions. Adding the protection period of a deep procedure to the short healing interval given for a superficial one, to form a single timetable, would also be wrong. Contacting a dermatologist for assessment if the skin burns, itches or swells after the procedure is among the AAD's recommendations.¹⁶ The distinction between an expected change and an unwanted effect should not be made by looking at the name of the procedure alone.¹

How should marketing language be read?

What do "deeper", "medical" and "at-home" not show?

"Deeper" describes an anatomical effect; it does not on its own say how much change was achieved for which complaint.³ Placing different targets and depths in the same order of success would mean treating a melasma score and the appearance of an acne scar as though they were the same outcome. Nor does the word "medical" take the place of explaining the physician's competence, the facility's authorisation and the class of the product separately.^14,15

In its warning of 30 July 2024, the FDA stated that high-concentration chemical peel products bought or used without professional supervision can lead to serious burns and skin damage.⁷ The same warning also records that the agency has not approved any chemical peel product; which institution and which decision the word "approved" describes on a product therefore has to be asked separately.⁷ The warning lists outcomes such as pain, swelling, infection, changes in skin colour and scarring, and notes that some injuries may require emergency or specialist care.⁷ This is a United States institutional warning about the risk of high-concentration unsupervised products; it is not a provision determining professional authorisation in Türkiye.

Being sold online is not proof of safe use; the FDA warning covers exactly these products offered to consumers.⁷ On the other hand, that warning does not say that all cosmetic exfoliation products act at the same depth or carry the same risk either. The Turkish Medicines and Medical Devices Agency's cosmetic boundary requires a separate assessment based on the product's effect and characteristics.¹⁵

An increase in a hydration measurement in one study cannot be translated into "all wrinkles are removed", nor improvement seen at a short follow-up into a "permanent result".^9,10 What makes assessment possible is not the attractive name of a method but which problem was examined with which comparison and over what period. The results here are therefore not presented as a recommendation of a method or a list for choosing a product.

How should the figures in this article be read?

The number of people and the number of procedures are different; Vemula's denominator of 473 is procedures, and Landau's denominator of 181 is people.^17,19 Because the raw figures of these two records describe different depths and different events, they cannot be added or used in place of one another.^17,19

Improvement from baseline and greater improvement than a comparison group are also different; the Hurley study shows that difference.¹³ Finding no statistically significant difference is not proof of equivalence, and a difference in one hydration measurement is not a general rate of rejuvenation.^9,10 A confidence interval describes the uncertainty of an estimate, and a follow-up period describes how long the outcome was observed. The figures here should not be used as a promise of an individual result, as a set of instructions or as a fixed care timetable.

References

1. DermNet. Chemical peels. Amanda Oakley; updated by Ebtisam Elghblawi. October 2018. Source ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰

2. DermNet. Dermabrasion. Vanessa Ngan. 2004. Source ↩ ↩² ↩³ ↩⁴

3. Chen X, Wang S, Yang M, Li L. Chemical peels for acne vulgaris: a systematic review of randomised controlled trials. BMJ Open. 2018;8(4):e019607. PMID 29705755. doi:10.1136/bmjopen-2017-019607 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰

4. Leheta T, El Tawdy A, Abdel Hay R, Farid S. Percutaneous collagen induction versus full-concentration trichloroacetic acid in the treatment of atrophic acne scars. Dermatol Surg. 2011;37(2):207-216. PMID 21269351. doi:10.1111/j.1524-4725.2010.01854.x ↩ ↩² ↩³ ↩⁴ ↩⁵

5. Sarkar R, Arsiwala S, Dubey N, et al. Chemical Peels in Melasma: A Review with Consensus Recommendations by Indian Pigmentary Expert Group. Indian J Dermatol. 2017;62(6):578-584. PMID 29263530. doi:10.4103/ijd.IJD_490_17 ↩ ↩² ↩³ ↩⁴ ↩⁵

6. Marçon CR. Phenol in dermatology: updated evidence on efficacy and safety. An Bras Dermatol. 2025;100(5):501200. PMID 40857991. doi:10.1016/j.abd.2025.501200 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

7. U.S. Food and Drug Administration. FDA warns against purchasing or using chemical peel skin products without professional supervision. 30 July 2024. Source ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

8. Sarkar R, Lakhani R. Chemical Peels for Melasma: A Systematic Review. Dermatol Surg. 2024;50(7):656-661. PMID 38530985. doi:10.1097/DSS.0000000000004167 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

9. Abdel Hay R, Shalaby K, Zaher H, et al. Interventions for acne scars. Cochrane Database Syst Rev. 2016;4:CD011946. PMID 27038134. doi:10.1002/14651858.CD011946.pub2 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹

10. Piejko L, Glenc-Ambroży M, Juszczyk J, et al. TCA chemical peel as facial anti-aging therapy for postmenopausal women: a randomised clinical study. Postepy Dermatol Alergol. 2025;42(1):28-41. PMID 40114772. doi:10.5114/ada.2024.144161 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰

11. Sitohang IBS, Legiawati L, Suseno LS, Safira FD. Trichloroacetic Acid Peeling for Treating Photoaging: A Systematic Review. Dermatol Res Pract. 2021;2021:3085670. PMID 34504524. doi:10.1155/2021/3085670 ↩ ↩² ↩³ ↩⁴ ↩⁵

12. Republic of Türkiye Ministry of Health. Standard for the Certified Training Programme in Aesthetic and Cosmetic Applications. 3 September 2025. Source ↩ ↩² ↩³ ↩⁴ ↩⁵

13. Hurley ME, Guevara IL, Gonzales RM, Pandya AG. Efficacy of glycolic acid peels in the treatment of melasma. Arch Dermatol. 2002;138(12):1578-1582. PMID 12472345. doi:10.1001/archderm.138.12.1578 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

14. Republic of Türkiye Ministry of Health. Regulation on Private Health Facilities Providing Outpatient Diagnosis and Treatment. Official Gazette, 19 April 2025, no. 32875; articles 4(1)(j), 6(10). Source ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

15. Turkish Medicines and Medical Devices Agency. Guide on Products Bordering on Cosmetic Products. KÜD-KLVZ-06; revision date 11.10.2024, revision 03 in the page footers. Articles 3 and 6, and example number 35 under article 9(4). Source ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰

16. American Academy of Dermatology. Chemical peels: FAQs. Source ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹

17. Vemula S, Maymone MBC, Secemsky EA, et al. Assessing the safety of superficial chemical peels in darker skin: A retrospective study. J Am Acad Dermatol. 2018;79(3):508-513.e2. PMID 29518457. doi:10.1016/j.jaad.2018.02.064 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹

18. American Academy of Dermatology. Chemical peels: Preparation. Source ↩ ↩² ↩³ ↩⁴

19. Landau M. Cardiac complications in deep chemical peels. Dermatol Surg. 2007;33(2):190-193; discussion 193. PMID 17300604. doi:10.1111/j.1524-4725.2006.33037.x ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷