What a Chemical Peel Actually Does
A chemical peel applies a chemical solution to the skin to exfoliate at a controlled depth. The goal is to prompt cell turnover and improve texture, tone, and overall appearance. The acid breaks the bonds between dead surface cells so they shed faster than they would on their own, which reveals fresher skin underneath and signals deeper layers to produce new tissue.
The state board cares less about brand names and more about what depth a peel works at, who is allowed to perform it, and which clients should not get one. This article walks through those topics in the order most exam questions follow.
The Three Peel Depths
Every peel falls into one of three depth categories. Knowing the depth tells you the recovery time, the risk level, and the scope of practice.
Superficial (Light) Peels
A superficial peel works only on the epidermis. There is no real downtime. Some clients have mild flaking for a day or two, but most return to normal activity right away. These peels can be done on a monthly schedule for ongoing maintenance.
Superficial peels are within the esthetician scope of practice in most states. They are the workhorse of a treatment room and include most glycolic, lactic, mandelic, salicylic, and lower-strength jessner peels.
Medium Peels
A medium peel reaches into the papillary dermis. Expect 5 to 7 days of visible peeling and redness, and the client should plan around social events. Medium peels are usually performed by nurse practitioners, physician assistants, or physicians, or by estheticians with advanced certifications under medical supervision, depending on the state.
TCA at moderate strengths and certain layered jessner-TCA combinations sit in this category.
Deep Peels
A deep peel reaches the reticular dermis. Recovery takes weeks, and there is real risk of scarring and pigment change. Deep peels are physician-only, performed in a medical setting with cardiac monitoring for phenol because it is absorbed systemically.
Common Acids by Category
Alpha Hydroxy Acids (AHAs)
AHAs are water-soluble and work on the skin surface. They are the most common acids in light peels and at-home products. The molecule size matters: smaller molecules penetrate faster and deeper.
- Glycolic acid comes from sugar cane. It has the smallest molecule of the AHAs, so it penetrates deepest. It is a popular pick for fine lines, dullness, and uneven texture.
- Lactic acid comes from milk. It hydrates while it exfoliates and is gentler than glycolic, which makes it a good choice for sensitive or dehydrated skin.
- Mandelic acid comes from bitter almonds. It has the largest AHA molecule, so it penetrates slowly and evenly. The slow penetration makes it a safer pick for darker skin tones because the risk of post-inflammatory hyperpigmentation (PIH) is lower.
Beta Hydroxy Acid (BHA)
The main BHA used in peels is salicylic acid. Unlike AHAs, BHAs are oil-soluble, so they can move through sebum and into pore openings. Salicylic acid is also anti-inflammatory, which makes it the go-to for oily and acneic skin.
Polyhydroxy Acids (PHAs)
PHAs include gluconolactone and lactobionic acid. They have very large molecules that stay near the surface, which makes them the gentlest of the hydroxy acid family. They are hydrating and well tolerated by sensitive skin and clients with rosacea-prone tissue between flares.
TCA (Trichloroacetic Acid)
TCA is most often used at medium-peel strength. Esthetician scope for TCA varies by state and by the percentage of the solution. Some states allow estheticians to apply low-strength TCA, while others restrict it entirely. Always check the local board rules before adding TCA to a service menu.
Jessner's Solution
Jessner's is a blended formula containing salicylic acid, lactic acid, and resorcinol. It produces a light to medium depth depending on how many layers are applied. It is self-neutralizing and frosts as it works.
Phenol
Phenol is the classic deep peel. It is physician-only and is performed under cardiac monitoring because it can be absorbed into the bloodstream. Estheticians do not perform phenol peels in any state.
Strength, pH, and How Acids Actually Work
A peel is described by two numbers: percentage and pH. Both matter, and exam questions often try to trick students who only think about percentage.
- Higher percentage means more acid molecules in the solution.
- Lower pH means more of the acid is in its free (active) form rather than buffered.
A 30 percent glycolic peel at pH 3 is much stronger than a 30 percent glycolic peel at pH 4, even though the percentage is identical. When comparing two products, look at both numbers.
Frosting, Flushing, and Neutralization
Different peels behave differently on the skin and need different end points.
- AHAs are typically applied for 2 to 7 minutes and then neutralized with water or a sodium bicarbonate solution. They do not stop working on their own.
- BHAs and jessner are self-neutralizing. They are removed by cleansing once the working time is up, but they do not require an active neutralizer.
- Frosting is a white film that appears as the acid coagulates protein in the skin. Light frosting can appear with stronger AHA peels and jessner. Even, white frosting on a TCA peel signals that the acid has reached medium depth, and the application stops at that point.
- Erythema (redness, sometimes called flushing) is normal during application and for hours afterward.
Contraindications
Skipping the consultation form is how estheticians get into trouble. Any of the following should pause or cancel a peel:
- Active acne flare in the treatment area
- Use of isotretinoin (Accutane) within the past 6 months
- Pregnancy or nursing, for some acids and percentages
- Recent retinoid use (typically stop 3 to 7 days before, longer for prescription strength)
- Recent waxing or other hair removal in the treatment area
- Active eczema or rosacea flare
- Broken, irritated, or sunburned skin
- Darker Fitzpatrick types (IV-VI) carry higher PIH risk and need conservative acids and lower percentages
- Immunosuppression or use of immunosuppressive medication
- Personal or family history of keloids or hypertrophic scarring
- Recent laser treatment or another resurfacing procedure
- History of cold sores; oral antiviral prophylaxis is sometimes recommended before perioral peels
Aftercare
What the client does in the days after the peel determines how the result looks. Set the rules out loud and on a printed card before they leave.
- Daily broad-spectrum SPF 30 or higher is mandatory. Sun exposure on freshly peeled skin causes hyperpigmentation that can take months to fade.
- No retinoids for 5 to 7 days after the peel.
- Use a gentle cleanser. No scrubs, no exfoliating tools, no enzyme masks.
- Apply a hydrating moisturizer to support the barrier as it rebuilds.
- Expect visible peeling 2 to 5 days after the treatment.
- Do not pick or pull at peeling skin. Pulling intact tissue creates the kind of trauma that leads to scarring and PIH.
What State Boards Tend to Ask
Exam questions on chemical peels cluster around a few topics:
- Matching a peel to the correct depth category
- Telling AHAs from BHA and explaining when to choose one over the other
- Recognizing contraindications, especially recent isotretinoin and active flares
- Post-care rules, especially SPF and the retinoid pause
- Scope of practice limits between estheticians, advanced estheticians, and medical providers
If you can answer those five categories cleanly, peel questions on the written exam stop being a guessing game.