Lip care guide: why lips dry and crack, what heals them, and what plumps them

Lips are among the most vulnerable skin structures on the body — anatomically unique in ways that make them prone to dryness, cracking, UV damage, and premature aging. Yet lip care is typically an afterthought. Here's the biology and the evidence-based approach.

Lip skin anatomy: why lips are different

No sebaceous glands

The vermilion (the red/pink lip border) has no sebaceous glands — zero intrinsic lipid barrier production. Unlike facial skin, which continuously replenishes surface lipids from sebum, lip skin has no self-hydrating mechanism. Every molecule of moisture protection must come from applied products or from the saliva glands and mucous membrane transitions at the inner lip.

The skin of the lips transitions from dry skin (outer) to mucous membrane (inner) — neither has the sebaceous gland-generated lipid barrier of normal skin.

Minimal stratum corneum

The lip epidermis has a much thinner stratum corneum than facial skin — approximately 3–5 cell layers vs. 15–20 on the face. This thin barrier:
Provides minimal protection against TEWL
Allows molecules to penetrate more readily (relevant for ingredient penetration and for sensitizer penetration)
Is more vulnerable to environmental desiccation (wind, cold air, dry environments)

No melanin

The vermilion contains minimal melanin (virtually none in lighter skin tones) — which is why lips appear red/pink (vascular color showing through) rather than the same tone as facial skin.

The absence of melanin means:
No UV protection — lips have essentially no intrinsic photoprotection
Extremely high cumulative UV damage over a lifetime
Actinic cheilitis: UV-induced dysplasia of the lip vermilion — the premalignant lip lesion equivalent to actinic keratosis; most common on the lower lip (which receives more direct UV)

Lip licking worsens dryness

Saliva contains amylase, lipase, and proteases — enzymes designed to digest food. On the lip skin, these enzymes disrupt the already-minimal barrier. The brief moistening of licking is followed by accelerated evaporation → net dryness worsening. The pattern of lip licking → temporary relief → worse dryness → more licking → "lick eczema" (perioral contact dermatitis from chronic saliva exposure) is a common clinical cycle.

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Causes of dry and chapped lips

| Cause | Mechanism |
|---|---|
| Cold, dry air | Accelerated TEWL through thin barrier |
| Wind | Increased evaporative water loss |
| Mouth breathing | Continuous airflow over lips → desiccation |
| Dehydration | Reduced tissue hydration throughout body; lips show earliest |
| Lip licking | Enzymatic barrier disruption + evaporative loss |
| Certain medications | Isotretinoin, retinoids, diuretics, antihistamines → reduced mucous secretion and skin hydration |
| Vitamin B12 / iron deficiency | Angular cheilitis (cracking at lip corners) |
| Contact allergens | Fragrance in lip products, nickel in dental appliances, cinnamon in toothpaste/food — cause allergic contact cheilitis |
| Isotretinoin | Dramatically reduces sebum and mucous membrane hydration; cheilitis is the most common isotretinoin side effect (>90% of patients) |

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Evidence-based lip care

Barrier repair: what works

Petrolatum (petroleum jelly):
The gold standard occlusive for lips. Reduces TEWL by up to 99%, allows the lip's own remaining moisture to be retained, creates a physical barrier against environmental stressors. Pure petrolatum (Vaseline) is the most effective, fragrance-free, and inexpensive lip treatment available.

Application: Apply generously as the last step PM; reapply throughout the day as needed. During severe dryness or isotretinoin use, apply every 2–4 hours.

Beeswax / plant waxes:
Lower occlusion than petrolatum but film-forming and widely used. Acceptable base for a lip balm; significantly less effective than petrolatum for severely dry lips.

Lanolin:
Highly effective emollient and occlusive; mimics the skin's own lipids; risk of sensitization in lanolin-allergic individuals (rare). Very effective for cracked lips.

Shea butter / cocoa butter:
Emollient; moderately occlusive; widely used in lip products. Less effective than petrolatum for TEWL reduction.

Glycerin + HA in lip products:
Humectants draw water into the stratum corneum. Useful when the environment is humid (>40% relative humidity) — in very dry air, humectants without occlusive overcoat can worsen dryness by drawing water from deeper tissues to the surface where it evaporates.

Ingredients to avoid in lip products

| Ingredient | Reason to avoid |
|---|---|
| Fragrance / flavor chemicals | The #1 cause of allergic contact cheilitis; common lip product fragrances include cinnamon, citrus, mint, vanilla |
| Menthol, camphor, phenol | Direct irritants to thin lip skin; cause a cooling sensation that feels refreshing but increases TEWL |
| Salicylic acid | Keratolytic on very thin lip barrier → worsens dryness and irritation |
| "Plumping" irritants (capsaicin, ginger, peppermint) | Cause vasodilation and mild inflammation for cosmetic swelling — chronic irritation worsens lip barrier |
| Hyaluronic acid as sole moisturizer (no occlusive) | Draws moisture to lip surface where it evaporates; needs occlusive pairing |

SPF on lips

Actinic cheilitis prevention — the premalignant UV-induced dysplasia of the lower lip — is a meaningful medical indication for daily lip SPF. The lower lip receives maximal direct UV (especially in outdoor workers and lighter-skinned individuals).

Use a lip balm with SPF 30+ containing mineral filters (zinc oxide) for daily protection. Reapply every 2 hours outdoors.

Progression of actinic cheilitis: Blurring of the vermilion border → scaly, pale patches on the lower lip → persistent erosions → squamous cell carcinoma in situ. Dermatology evaluation for any persistent lower lip scaling or erosion that does not resolve with consistent moisturization.

Retinol for lip anti-aging

The vermilion develops fine vertical lines ("lip lines") primarily from:
Repeated perioral muscle contraction (orbicularis oris)
UV damage thinning the vermilion

Retinol 0.025–0.05% applied to the vermilion border (the skin just outside the lip proper) 2–3 nights/week improves perioral fine lines. Do not apply to the vermilion itself — the thin mucous-membrane-transitional skin is too reactive; apply to the perioral skin surrounding the lip.

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Lip plumping: topical vs. filler

Topical "plumping" — what it actually does

Most topical lip plumpers work by inducing mild irritant inflammation — capsaicin, peppermint oil, and ginger extract cause transient vasodilation and very mild swelling, producing a temporary 1–4 hour plumping effect. This is not structural change — it is irritant-induced edema.

Hyaluronic acid in lip serums: HA at the skin surface acts as a humectant, temporarily hydrating and subtly plumping the surface. The effect is visible in before/after photography under good lighting conditions — a hydration effect, not volume restoration. Does not replicate filler.

Peptides in lip products (collagen-stimulating): Slow, modest structural benefit through collagen synthesis stimulation. Not comparable to filler for volume.

Hyaluronic acid lip filler

Filler is the only intervention that meaningfully increases lip volume. HA filler (1–3 mL typical) injected by an experienced provider:
Increases lip volume (cupid's bow definition, vermilion border sharpness, overall projection)
Can correct asymmetry
Results last 6–18 months depending on product and patient

Risks at the lip: The labial arteries run within or adjacent to the lip — vascular occlusion from HA filler at this site is a known complication, including rare reports of skin necrosis. Must be performed by an experienced injector with hyaluronidase available. Technique (cannula vs. sharp needle, aspiration, product choice) significantly affects complication rates.

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The lip care routine

Daily:
Fragrance-free SPF 30+ lip balm with zinc oxide (AM; reapply outdoors)
Petrolatum lip balm as needed throughout the day and before bed

If lips are actively dry or chapped:
Gently exfoliate 1× weekly with a soft toothbrush + small amount of fragrance-free lip balm (mechanical only; no chemical exfoliants on vermilion)
Apply a thick layer of petrolatum at night for 7–10 days consistently

For perioral anti-aging:
Retinol 0.025–0.05% to the perioral skin (not the vermilion itself) 2–3 nights/week

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