Everything You Need to Know About Chemical Peels – Skin Rocks

Chemical Peels 101

Thinking about getting a chemical peel? Get the low-down on the popular cosmetic treatment as Advanced Skin Facialist, Andy Millward covers all you need to know. 

What is a chemical peel? 

A chemical peel is a broad term used to describe a solution that is applied to the skin to stimulate the renewal process, resurface the outermost layer of the skin (the upper epidermis) and help stimulate collagen production in the dermis (the middle layer of the skin).

How does it benefit the skin?  

The benefits of a chemical peel can vary depending on the type of peel used. Broadly speaking, they can be useful for treating a variety of skin concerns such as sun damage, hyperpigmentation, lines and wrinkles, uneven skin texture, acne, acne scarring, congestion and dullness.

Is there downtime?

Contrary to the name, not all chemical peels cause physical peeling. The level of downtime and peeling depends on the strength of the peel and the depth of penetration and can be categorised in the following way: 

  • Very Superficial Peels – work on the upper layers of the stratum corneum (uppermost layer of the skin) only. Typically, no peeling but you may experience dryness for a few days.

  • Superficial Peel – can penetrate as low as the stratum granulosum (near the base of the top layer of the skin) and may cause some mild sheathing, which resembles peeling skin similar to sunburn.

  • Medium Depth Peels – can penetrate to the upper papillary dermis (at the top of the middle layer of the skin) and will likely induce ‘epidermolysis’, where the shedding skin resembles sheets.

  • Deep Chemical Peels – can penetrate to the reticular dermis (the bottom of the middle layer of the skin). Typically, this would be done in a surgical setting under general anaesthetic and would have weeks of downtime and wound management.

Types of chemical peels

Peels can be categorised by the main active ingredients. Most commonly this will be some form of acid but enzymes and retinol peels are also popular.

  • Mono-Agent Peels: a peel containing a single acid or active e.g., a Glycolic Acid Peel

  • Combination Peels: a peel containing a blend of acids/actives e.g., a Jessner Peel which contains 14% Lactic acid, 14% Salicylic acid and 14% Resorcinol. 

What determines the strength of a chemical peel?

Peels can vary in strength dramatically and there are lots of variables that determine their depth of penetration. These include:

  • Type of active used – e.g., AHA’s, BHA’s, Retinol etc.

  • Percentage – the concentration of acid used. For example, a 20% salicylic acid peel or a 50% glycolic acid peel. Percentages often confuse people but it’s only one component in determining the ‘potential’ strength of a peel. For example, a 30% Glycolic Peel with a pH of 1.6 would be stronger than a 40% Glycolic Peel with a pH of 3.5, due to its ability to penetrate deeper.

  • pH of the solution – The lower the pH, the more acidic the solution, and the greater potential for penetration.

  • pKa measurement – Used to determine the level of free acid available (more applicable for buffered peels).

  • Buffered – buffering refers to the addition of a base (alkaline) solution to raise the pKa value and pH, therefore making the peel weaker.

  • The number of passes – Some peels can be ‘layered’, such as Jessner peels. The more layers, the stronger the treatment.

  • Timing – Many peels require neutralising to ‘stop’ the peel from working and control the depth of penetration. A peel may only be on the skin for anywhere from 30 seconds to a few minutes. Some peels are ‘self-neutralising’ and are left on the skin for several hours.

Is a chemical peel suitable for everyone?

One of the great things about having a variety of different chemical peel types and strengths is the availability of options suitable for all skin types and concerns being treated. That said, there are some contraindications that need to be considered. These may vary depending on the supplier and should be discussed prior to treatment during a consultation with the practitioner treating you:

  • Roaccutane (current or within 6 months)

  • Photosensitising or skin thinning medications

  • Pregnancy

  • Cancer or undergoing chemotherapy/radiotherapy

  • Recent surgery or open wound (in the treatment area)

  • Eczema or other skin barrier disorders

  • Active skin infection

  • Impaired immune function/poor healing

  • Keloid scarring

Why pre-peel prep/skin priming is important

Skin priming is the process of conditioning the skin in the weeks/months leading up to a peel. It will typically comprise of using AHA’s, retinoids and possibly tyrosinase inhibitors (ingredients that inhibit a key enzyme involved in melanin production) if needed.

The goal of priming the skin is to make the treatment safer (especially when using chemical peels on darker skin tones when there is an increased risk of post-inflammatory hyperpigmentation), ensure there is a more predictable outcome and enhance the results from treatment. It also helps to strengthen the skin barrier, improving the overall health of the skin tissue and conditioning the skin's tolerance to the ingredients used in the peel to aid recovery and prevent excess wounding.

Priming is typically not required for very superficial peels but is an important step for superficial, medium-depth and deep peels. The practitioner treating you should advise on what is required.

What to look for when choosing a practitioner

Make sure the practitioner is qualified, trained and insured to carry out the treatment. In order to provide a chemical peel, they should have a minimum of Level 3 qualification (a recognised qualification on the OFQUAL framework such as CIBTAC or VTCT) and have completed manufacturer training in chemical peels. Ideally, I would also like to see a Level 4 Chemical Peel qualification (again on the OFQUAL framework) but not everyone will have this.

‘I echo this.’ – Caroline Hirons, Founder.

When things go wrong

Chemical peels don’t come without risks. When you are dealing with acids, things can go wrong and risks include redness, swelling, itching, acne breakouts (irritation purging), post-inflammatory hyperpigmentation and even infection and scarring for deeper peels.

This is why a thorough consultation and skin analysis is needed to ensure suitability for treatment and to make sure the skin is prepped (if necessary) and the skin barrier is strong enough to cope and recover from the treatment.

When I used to teach chemical peeling for both a brand and at CIBTAC Level 4 diploma level, I had a saying; “any good Facialist can learn how to apply a peel, but a great Facialist learns when not to apply a peel.”


Words by Andy Millward, Advanced Skin Facialist 

Qualifications - CIBTAC Level 4 Diploma in Aesthetic Practice 

Follow Andy @andymillward_