How often does your skin renew itself?

Why isn't there one exact number?

Renewal includes several stages: making cells, moving them through the epidermis, forming the protective surface and eventually shedding. A number for time spent at the surface is not the same as a number for the whole process. New cells reach the outermost layer after about a month, while estimates for complete epidermal turnover extend to 40 to 56 days.34

What actually happens during skin renewal?

Stem cells in the basal layer, the deepest part of the epidermis, generate new cells. These become keratinocytes, the main cells of the epidermis. As keratinocytes move upward, they mature and flatten. Eventually they lose their nuclei and become corneocytes, the dead cells that make up the stratum corneum, your outermost protective layer.23

Corneocytes and the fats between them help protect your body and control water loss. Surface cells gradually loosen and fall away as replacements arrive from below. The surface cells are dead but still protect the body, which is a fairly demanding retirement.24

Does all your skin get replaced?

The turnover clock describes the epidermis, not every structure beneath it. The dermis underneath contains collagen and elastin, while the deeper hypodermis helps store energy and connects skin to muscles and bones. Replacing the epidermis is not replacing the whole skin, despite how much work the word "renewal" is being asked to do.45

Wound healing is also different from ordinary turnover. After an injury, the body forms a clot and grows new cells to replace damaged tissue. A deep enough injury can leave a scar. Renewal becomes faster after epidermal injury and in some skin diseases, particularly psoriasis, so faster turnover is not automatically healthier skin.25

Should you exfoliate to speed renewal?

Normal renewal already includes shedding surface cells. Chemical peels help exfoliate by disrupting the top layer so cells slough off; they can make skin look brighter or improve texture. That is different from needing a peel to keep the epidermis renewing.36

If you choose a home peel, test a small amount on the jawline or behind an ear and wait a day before treating your whole face. Be especially careful with sensitive or dry skin or eczema. Retinol, tretinoin and adapalene can make a peel penetrate more deeply, increasing its effects and downtime.6

How do you care for skin while it renews?

• Wash with mild soap and lukewarm water, then pat dry rather than rubbing.
• Apply moisturizing cream or ointment immediately after drying to help seal in moisture.
• Wear SPF 30 or higher outdoors, reapply every two hours and use shade and protective clothing.
• Avoid scratching or rubbing irritated skin.