Olive Oil on Skin: What the Research Actually Shows

Olive oil is one of the oldest cosmetics in the world and one of the most confidently recommended things in any kitchen. The research on putting it on skin is small, but the best study in it is unusually clean, unusually British, and points the other way. This page reports what was measured.

Plate I · IllustrationRecord

What did the Sheffield trial find?

That olive oil measurably damaged the skin barrier, and that a different kitchen oil did not.

Danby and colleagues at the University of Sheffield ran two randomised forearm-controlled studies in nineteen adult volunteers, some with a history of atopic dermatitis and some without. The design is the useful part: a forearm-controlled trial uses each participant as their own comparison, one arm treated and the other not, so differences between people cancel out. The first cohort applied six drops of olive oil to one forearm twice daily for five weeks. The second applied six drops of olive oil to one forearm and six drops of sunflower seed oil to the other, twice daily for four weeks. The researchers then measured stratum corneum integrity and cohesion, hydration, skin-surface pH and erythema.

Four weeks of olive oil produced a significant reduction in stratum corneum integrity and induced mild erythema — redness — and it did so in volunteers with and without any history of atopic dermatitis. Sunflower seed oil, on the other arm of the same people, preserved barrier integrity, caused no erythema, and improved hydration.

Fig. I · Two forearms, one personDiagram

Nineteen adults, with and without a history of atopic dermatitis. Each person carried both treatments — one arm each — so everything that differs between people cancels out.

Olive oilsix drops, twice daily, 4 weeks

• ↓Stratum corneum integrity significantly reduced
• ↑Mild erythema induced — redness
• ·In volunteers with and without an atopic dermatitis history

Sunflower seed oilsix drops, twice daily, 4 weeks

• →Stratum corneum integrity preserved
• →No erythema
• ↑Hydration improved

Also run

A separate cohort applied six drops of olive oil to one forearm twice daily for five weeks. The result above is attributed to the four-week comparison, so it is the one drawn.

Measured

Stratum corneum integrity and cohesion · intercorneocyte cohesion · moisturisation · skin-surface pH · erythema.

No sizes drawn

The trial reports directions and significance, not magnitudes. Nothing here is scaled, because there is no published figure to scale it to.

The authors' recommendation: use of olive oil for the treatment of dry skin and infant massage “should therefore be discouraged”.

The authors’ conclusion is not hedged: topical olive oil “significantly damages the skin barrier, and therefore has the potential to promote the development of, and exacerbate existing, atopic dermatitis”, and its use “for the treatment of dry skin and infant massage should therefore be discouraged”. They framed the study as a test of an assumption — that natural oils are advocated and used throughout the world in neonatal skin care in the absence of evidence — and it is worth reading their closing line as the point of the whole exercise: the findings “challenge the unfounded belief that all natural oils are beneficial for the skin”.

What it is: nineteen people, a mechanistic study of biophysical measurements rather than a trial of a disease outcome, and short. What it is not: a study anyone has contradicted with better evidence.

Why would an oil that is good to eat be bad on skin?

Because the two questions have almost nothing to do with each other, and the fatty acid that makes olive oil what it is behaves differently on a barrier than in a diet.

Olive oil is roughly 73% oleic acid, a monounsaturate. Sunflower oil is dominated by linoleic acid, a polyunsaturate. That single compositional difference is the most likely explanation for the split in the trial: oleic acid is a long-established penetration enhancer, used precisely because it disorders the ordered lipid layers that hold the stratum corneum together. That property is valuable when the object is to get a drug through skin. It is the opposite of valuable when the barrier is the thing you were trying to help.

Fig. II · Oleic against linoleicDiagram

Two kitchen oils came off the same trial with opposite results. The most plausible reason is one compositional difference, drawn below.

Olive oilfatty acids, drawn to scale

73% monounsaturated — overwhelmingly oleic acid13.8% saturated10.5% polyunsaturated

The three shares sum to 97.3%. The remainder is unassigned in the source, so the bar is left short rather than padded out to fill its track.

Sunflower seed oilthe other arm of the trialNo bar drawn

A linoleic-acid oil — a polyunsaturate, where olive oil is a monounsaturate. No fatty-acid breakdown for it was fetched for this figure, so it is named and not measured.

Why the difference would matter on skin

Oleic acid is a long-established penetration enhancer: it disorders the ordered lipid layers that hold the stratum corneum together. That is a useful property when the object is to get a drug through skin, and the opposite of useful when the barrier is the thing you were trying to help. The same acid is the irritating free fatty acid investigated in the dandruff model, where sensitivity to it varies from person to person.

This is the explanation, not the finding. The trial compared two oils and measured a difference; it did not isolate an acid.

None of this touches the food question. The trials that made olive oil’s reputation measured what happens when people eat it — those are on is olive oil good for you — and a barrier study on a forearm neither supports nor undermines them. It is the same substance answering a different question, and it answers this one badly.

What about babies?

This is where the Sheffield team started, and where the evidence is most worth having.

Natural oils are used in neonatal skin care around the world, and the researchers were explicit that the practice runs ahead of any evidence supporting it. Their own result named infant massage as a use to discourage. And the broader literature has not rescued the idea from another direction: the 2022 Cochrane review of skin care interventions in infants, covering emollients given in the first year of life to healthy babies, concluded on low- to moderate-certainty evidence that they are probably not effective for preventing eczema, may increase the risk of food allergy, and probably increase the risk of skin infection.

That review is about emollients generally rather than olive oil specifically, and the distinction matters. But the two findings point the same way, and they point away from the assumption that oiling a baby’s skin is a neutral or gentle thing to do.

Anything concerning an infant’s skin belongs with a health visitor, midwife or GP. A food company’s role here is to report the research and stop.

Does olive oil help acne, or clog pores?

There is no trial of olive oil for acne to report — not a small one, not a poor one. What exists is a mechanism worth knowing, and it comes from the dandruff literature.

Dandruff and seborrhoeic dermatitis are driven by three things together: Malassezia yeasts, which live on sebum; the free fatty acids those yeasts release from sebaceous triglycerides; and individual sensitivity to those fatty acids. In the paper that set out that model, the toxic free fatty acid metabolite used to represent the group — the one whose effects were investigated — was oleic acid. Some people react to it and some do not, and that individual susceptibility is a defined part of the model rather than an aside.

Oleic acid is the majority fatty acid in olive oil. That does not prove olive oil causes acne, and this page will not say that it does: the dandruff work was about scalp sebum, not about applying a cooking oil to a face. But if you have skin that reacts to oils and you have been told olive oil is the gentle option, the composition is at least worth knowing about.

What are the real risks worth knowing?

Three, and none of them is dramatic.

The barrier effect is the main one, and it is the finding above: neat olive oil, twice daily, reduced stratum corneum integrity and produced mild redness in a month, in people with and without eczema histories.

Sunburn is not a use for it. Olive oil offers no meaningful protection from ultraviolet light, and burned skin has a compromised barrier already. NHS guidance on sunburn is the right starting point.

Allergy to olive is uncommon but real, and anyone who reacts to an oil on skin should stop using it. That is ordinary advice and applies to any oil.

How should the shelf claims be read?

With the register in one hand. In Great Britain, a health claim on a food may only be used if it is authorised on the nutrition and health claims register — and the only authorised wording that names olive oil concerns blood lipids in people who eat it, conditional on the oil’s polyphenol content. Nothing on that register authorises a skin claim for olive oil. Cosmetic products are governed under a different regime entirely, with its own rules about what a label may say, so “contains olive oil” on a cream is not making the food register’s claim and is not evidence of anything this page has measured.

So what does the record actually show?

Small literature, clear direction. The one properly controlled study to compare olive oil against another kitchen oil on human skin found that olive oil reduced barrier integrity and caused mild redness, that sunflower seed oil did neither and improved hydration, and that the difference held in people with and without a history of eczema. Its authors recommended against using olive oil for dry skin and infant massage. A large Cochrane review of infant emollients points the same way about oiling babies generally. There is no trial of olive oil for acne, and the closest mechanistic evidence — from dandruff research — puts oleic acid on the irritant side of the ledger for susceptible people.

The honest summary is that olive oil is a good food with a poor topical record, and that those two facts sit together without contradiction. What the eating evidence shows is a separate page: is olive oil good for you. What the same oil does on hair is olive oil for hair.

Where THYMELIA stands

THYMELIA is a UK house of Greek foods — raw thyme honey from Chania in western Crete, and early-harvest extra virgin olive oil from the hills above Kalamata. We sell food, and we have no cosmetic to defend, which is the only reason this page is easy to write: reporting that the topical evidence runs against olive oil costs us nothing. There is no shop yet, and we name no date for one. What the research says about the honey side of the same question is at honey on skin, and how we choose a harvest is at sourcing.