How often is your skin replaced?

How does skin replace itself?

New cells form in the basal layer, the deepest part of the epidermis. Stem cells there generate daughter cells that move upwards and mature. The main surface cells are called keratinocytes because they produce keratin, a protein that helps give the skin its protective structure. As these cells rise, they flatten and accumulate keratin. Eventually, they become dead surface cells called corneocytes, which loosen and fall or rub off.234

The outermost layer is called the stratum corneum. Those dead surface cells help form a protective barrier, which is a better job description than 'stuff to scrub off'. The epidermis helps prevent water loss and keeps unwanted substances and organisms from entering the body. Dead cells are therefore part of normal, functioning skin, not simply waste waiting to be removed.34

Is it exactly 28 days?

No single number describes every stage of renewal. Keratinocyte renewal is described as taking 15 to 30 days, while the movement of daughter cells from the basal layer to form the surface layer is described as taking 28 to 60 days. Full epidermal turnover is also estimated at 40 to 56 days. Treat 'about a month' as shorthand for an ongoing process, rather than an exact personal schedule.24

Renewal speeds up when the epidermis is injured and in certain skin diseases, particularly psoriasis. A faster rate is not automatically a sign of healthier skin.4

What about the deeper skin layers?

The epidermis is only the outer layer, so 'new skin' is a rather ambitious name for a surface refurbishment. Beneath it, the dermis is a supporting layer containing collagen, elastin, nerves and blood vessels. Collagen gives skin strength, while elastin gives it flexibility. Cells called fibroblasts produce collagen and other supporting material for growth and wound repair. Below the dermis sits the subcutis, or fatty layer. Surface shedding is not the replacement of these deeper structures.13

What should you do while skin renews?

Support the protective layer with gentle cleansing morning and night and moisturizing lotion to prevent dryness. Apply broad spectrum sunscreen with SPF 30 or higher every day, including days spent mostly indoors. These are skin care habits, not a countdown to completely new skin.1

Do not wait for a renewal cycle to pass before getting an unexplained rash checked. Contact a healthcare provider for a new mole, a mole changing in size, colour or shape, or signs of infection such as red streaks or yellow discharge.1