Provitamin B5 is panthenol, a stable alcohol form of vitamin B5 (pantothenic acid) that converts into the active vitamin after your skin absorbs it. It’s one of the most common ingredients in skincare and haircare products because it moisturizes, soothes irritation, and helps repair the skin barrier. You’ll find it on ingredient labels listed as panthenol, dexpanthenol, or D-panthenol.
How Provitamin B5 Works in Your Body
Panthenol itself isn’t a vitamin. It’s a precursor, meaning your body has to convert it before it becomes useful. Once panthenol penetrates the skin, enzymes break it down into pantothenic acid, the actual vitamin B5. Pantothenic acid then becomes part of coenzyme A, a molecule involved in hundreds of cellular processes, including building the fatty acids and lipids that hold your skin barrier together.
This conversion is the whole reason provitamin B5 exists in skincare. Pure pantothenic acid is unstable in liquid formulations and breaks down quickly. Panthenol, by contrast, stays stable in products with a pH between 3 and 5, which covers most serums, creams, and masks. It’s essentially a delivery vehicle: stable on the shelf, active once it reaches your cells.
Not All Panthenol Is Biologically Active
Panthenol comes in two mirror-image forms. The D-form (dexpanthenol) is biologically active and converts into vitamin B5 in your tissues. The L-form does not. Many products use a 50/50 racemic mixture of both, which means only half the panthenol in the formula is doing the biological work. Products listing “dexpanthenol” or “D-panthenol” specifically contain only the active form.
Skin Hydration and Barrier Repair
Provitamin B5 works as a humectant, pulling water into the outer layer of skin and helping it stay there. It also interacts with the lipid and protein layers of skin cells, reducing moisture loss by maintaining the fluidity of those layers. This dual action is why it shows up in products marketed for both hydration and barrier repair.
Clinical data backs this up. In a double-blind controlled study on patients recovering from facial laser treatment, a panthenol-enriched mask significantly reduced transepidermal water loss (the rate at which moisture escapes through skin) compared to a control group at 3, 7, and 14 days post-treatment. By day 14, the panthenol group had water loss rates of about 11.5 g/h/m² versus 16.1 in the control group. Stratum corneum hydration was also consistently higher in the panthenol group, reaching 51.5% compared to 44.8% at the two-week mark.
These findings reflect what earlier research has consistently shown: topical panthenol improves stratum corneum hydration and accelerates the restoration of the skin’s protective barrier after damage.
Wound Healing and Irritation
Beyond everyday moisturizing, provitamin B5 has a meaningful role in skin repair. Once converted to pantothenic acid, it supports the production of new skin cells. Lab studies have shown that fibroblasts (the cells responsible for producing connective tissue) proliferate faster when exposed to the active form of vitamin B5. In clinical settings, wounds treated with dexpanthenol show faster re-epithelialization, the process of new skin growing over a wound, along with better cosmetic outcomes compared to standard treatments like petroleum jelly.
It also reduces inflammation caused by common irritants. In a study where skin irritation was deliberately triggered using sodium lauryl sulfate (a harsh surfactant found in many cleansers), a dexpanthenol-containing cream significantly accelerated barrier repair compared to both a vehicle cream and untreated skin. This is part of why panthenol is a go-to ingredient in products designed for sensitive or reactive skin.
Common Medical and Consumer Uses
Panthenol-containing products span a wide range. In over-the-counter medical products, dexpanthenol ointments have been used for decades to treat infant diaper rash. One well-known product, Bepanthen, has been registered in France as a medicinal product for irritant diaper dermatitis since 1995. It works by maintaining the skin barrier and reducing inflammation in the diaper area, where constant moisture and friction break skin down.
Beyond diaper rash, topical panthenol is used for dry skin conditions, itching, and minor skin irritations including mild eczema. Dermatologists also recommend it as part of post-procedure care after laser treatments, chemical peels, and other cosmetic procedures that temporarily compromise the skin barrier.
In everyday consumer products, you’ll find panthenol in face creams, body lotions, lip balms, sunscreen formulas, and after-sun products. Its soothing and anti-irritant properties make it versatile enough to appear in products for nearly every skin type.
Benefits for Hair
Provitamin B5 penetrates the hair shaft rather than just coating the surface. Once inside, it binds to the hair’s internal structure, which increases each strand’s ability to hold moisture. The practical result is hair that feels thicker, softer, and more elastic. Panthenol also reaches the scalp, where it functions the same way it does on skin: hydrating and reducing irritation.
Shampoos, conditioners, and leave-in treatments commonly include panthenol for these reasons. Because it bonds to hair rather than rinsing away completely, even rinse-off products deliver some lasting benefit.
How It Differs From Vitamin B5 in Food
Pantothenic acid from your diet and provitamin B5 in skincare serve the same vitamin function, but they reach your skin through completely different routes. Dietary vitamin B5, found in foods like chicken, eggs, avocados, and mushrooms, gets absorbed in the gut and distributed throughout the body. Very little of it preferentially targets skin cells. Topical panthenol, on the other hand, delivers the vitamin directly where it’s applied, producing localized effects on hydration, barrier function, and healing that dietary intake alone can’t replicate.
Vitamin B5 deficiency is extremely rare because the nutrient is present in nearly all foods (its name comes from the Greek word “pantos,” meaning everywhere). So the skincare use of provitamin B5 isn’t about correcting a deficiency. It’s about concentrating the vitamin’s effects exactly where you want them.