Facial chemical peel: superficial or medium-depth TCA, how to choose?

Two depths of facial chemical peel

A medical peel means applying an acid to the skin, at a controlled concentration and for a controlled time. The surface exfoliates, then the skin renews itself underneath. What changes everything is the depth reached.

• A superficial peel stays within the epidermis, the outermost layer of the skin. It uses alpha hydroxy acids such as glycolic acid, or salicylic acid. At the practice, it is done as a series of four sessions, with no social downtime; guidelines space the sessions two to four weeks apart.
• A medium-depth peel with trichloroacetic acid, often simply called a "TCA peel", goes through the whole epidermis and reaches the upper dermis. It is done in one to three sessions, with a few days of downtime.

What a peel can improve

The recognised indications concern the surface of the skin:

• dull skin, uneven texture, fine lines caused by the sun (mild photoageing);
• superficial pigment spots;
• superficial acne scars, rather with a medium-depth peel;
• enlarged pores: in a small Japanese study, 22 women received five glycolic acid peels, and the number of visible pores fell in most of them. This is encouraging, but needs confirming.

Melasma, the brown patches on the face encouraged by sun and hormones, calls for caution. It often comes back. Its core treatment remains a depigmenting cream and strict sun protection; a peel is only a second-line treatment, as an add-on.

On the other hand, a peel does not act on volume, deep lines or sagging: these concerns call for other approaches.

Preparing the skin, two to four weeks before

Preparation is mainly there to reduce the risk of dark marks after the peel. For two to four weeks, I ask you to apply a sunscreen every day and a cream chosen for your skin, for example a retinoid or a depigmenting agent. Some of these products are stopped one day to one week before the session, depending on the product, so as not to irritate the skin. If the preparation could not be followed, I prefer to postpone.

Olive and dark skin: the risk of dark marks

Any inflammation of the skin can leave a brown mark: this is called post-inflammatory hyperpigmentation. It can last a long time and is hard to treat. In olive to dark skin, this risk is clearly higher, especially with medium-depth and deep peels.

For these skin types, I therefore favour superficial peels, with thorough preparation and strict sun protection. A medium-depth TCA peel is only considered with great caution, and sometimes not at all. The practice's rule applies here too: the first time, we always do less.

After the peel: recovery and the sun

After a superficial peel, redness and fine flaking usually last one to three days, without stopping you from working. After a medium-depth peel, the skin turns red, swells a little and then peels for five to fourteen days depending on the case: plan a few days at home.

Sun protection is then essential for several weeks: broad-spectrum sunscreen every day, no sun exposure, no sunbeds. It is what limits the risk of dark marks. That is also why I rarely do peels in summer: in autumn and winter, avoiding the sun is much easier.

When we do not peel

• An active cold sore (herpes): we wait for it to heal. If you have had them before, an antiviral is prescribed before a medium-depth peel, starting two days before and continuing for seven to ten days.
• Current or recent isotretinoin treatment (acne tablets). For a medium-depth peel, guidelines from 2008 ask you to wait six months after stopping. For a superficial peel, a 2017 review found no solid reason to wait; we discuss it case by case.
• Pregnancy: salicylic acid and TCA should be avoided or used with caution. Glycolic and lactic acids are considered safe because they penetrate very little, although data remain limited; as a precaution, I prefer to wait until after the pregnancy.
• A wound, infection or eczema on the face, a tendency to thick scars (keloids), a medicine that makes the skin sensitive to the sun, or recent or planned sun exposure.

How I work

The consultation starts with an examination of your skin and your phototype (how it reacts to the sun), followed by a computer analysis of your face. I tell you which depth seems suitable, or whether a peel is not the right answer. You leave with written information and a quote. Because the skin is prepared first, the peel usually takes place at a later appointment; we then compare the changes on the same photographs.