Lavender oil – skin savior or skin irritant?

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A question came up recently on TheBeautyBrains forum: Lavender oil in cosmetics – does it cause skin cell death, and is that a problem? This was in response to the description of “lavender extract and oil” on Paula Begoun’s Cosmetic Ingredient Dictionary. Paula is known for her belief that fragrances, natural or synthetic, have no place in cosmetic products. Here are some random examples from her website: “Cedarwood oil: there is evidence that cedarwood oil is allergenic and can cause skin irritation. Rose oil: Fragrant, volatile oil that can be a skin irritant and sensitizer. Tangerine oil: Fragrant, volatile citrus oil that can be a skin irritant.” And so on. In her profile of lavender oil, she goes out of her way to find negative information, but is hard pressed to find anything positive to say:

Lavender: widely-used plant that’s a member of the mint family. It is primarily a fragrance ingredient, although it may have antibacterial properties. There is no research showing it has any benefit for skin (Sources: Phytotherapy Research, June 2002, pages 301–308). In fact, it can be a skin irritant but there is a conflicting research on just how much of a photosensitizer lavender can be. It appears lavender oil all by itself isn’t a photosensitizer, but when exposed to oxygen (as it would be when applied to your skin), one of it’s fragrant components, linalyl acetate forms substances that lead to allergic contact dermatitis in and out of sunlight (Sources: The New Ideal in Skin Health: Separating Fact from Fiction, Thornfeldt, Carl M.D., Allured Books, 2010, pages 286–287; Contact Dermatitis, January 2008, pages 9–14; Hautarzt, February 2002, pages 93–97; and Contact Dermatitis, August 1999, page 111).

Research also indicates that other components of lavender, specifically linalool, can be cytotoxic, meaning that topical application causes skin-cell death (Source: Cell Proliferation, June 2004, pages 221–229). Lavender leaves contain camphor, which is known as a skin irritant. Because the fragrance constituents in lavender oil oxidize when exposed to air, lavender oil is pro-oxidant. This enhanced oxidation also increases its irritancy on skin (Source: Contact Dermatitis, September 2008, pages 143–150). Lavender oil is the most potent form, and even small amounts of it (0.25% or less) can be problematic. It is a must to avoid in skin-care products, but is fine used as an aromatherapy agent for inhalation or relaxation (Source: Psychiatry Research, February 2007, pages 89–96; and www.naturaldatabase.com).

Let’s take a look at these points one at a time.

“There is no research showing it has any benefit for skin”

Well, this was almost true in 2002, but not quite. Of the articles I’m about to cite, all except three were published either in 2002, or later. But today, this statement makes no sense. One of the early papers was on wound healing (Guba 1998/1999). A mixture of oils including 4% lavender oil was used on 18 patients with skin ulcers or wounds. In most cases the formulation was applied daily, and healing took from 5 days to 12 weeks. There were no adverse reactions. In an anti-allergic study, lavender oil, applied to the skin of rats or mice at 0.1%, 1.0%, 10% or 100%, inhibited immediate-type allergic reactions. It also inhibited the release of the inflammatory mediators, TNF and histamine (Kim & Cho 1999). In a clinical trial of 120 women post-childbirth, lavender oil sitz baths (a few drops in water) significantly reduced redness during healing after episiotomy (Vakilian et al 2011). Two other studies have reported positive effects for lavender oil in wound healing (Hartman & Coetzee 2002, Kerr 2002). No adverse reactions were reported in any of the above studies. Hartman & Coetzee also used lavender oil at 4%, and blue chamomile oil at 2%.

Lavender is one of the most active essential oils against MRSA (Edwards-Jones et al 2004), and the benefits of preventing MRSA establishing itself on your skin should not be underestimated. Lavender oil is moderately active against Propionibacterium acnes (Zu et al 2010), one the the principal bacteria involved in acne. It is moderately active against two of the principal fungi that can cause skin problems such as athlete’s foot and ringworm (Trycophyton rubrum and T. mentagrophytes) (Cassella et al 2002), and highly active against a third, Candida albicans (D’Auria et al 2005). The use of up to 0.5% of lavender oil in aqueous body milks allowed the regular synthetic preservative to be cut back by up to 8.5 times without any reduction in efficacy (Kunicka-Styczynska et al 2009). Lavender oil is very effective against some problematic bacteria and fungi found on the skin, but not all (Kunicka-Styczynska et al 2011, Sokovic et al 2010) so it would not be appropriate to use as a stand-alone preservative.

There is anecdotal evidence that lavender oil is a useful remedy for burns (Gattefossé 1993, p87). This is supported by the antimicrobial data above (i.e. preventing infection), and by the fact that lavender oil has a proven analgesic action (Ghelardini et al 1999, Sakurada et al 2009). This action is mostly due to linalool, and may also explain why lavender oil reputedly soothes bee stings, something I can personally attest to. Burns too.

Ultra-violet (UV) radiation can damage the skin because it leads to the generation of free radicals. The body has a limited amount of protective antioxidant enzymes, and these enzymes tend to decrease with age, making the skin more vulnerable to oxidative stress. A Japanese study reported that lavender oil inhibited the generation of singlet oxygen, which causes the most damage in response to UVA/UVB radiation (Sakurai et al 2005). This suggests that the regular use of lavender oil in skin preparations could suppress the aging effects of sunlight on the skin. Lavender oil has shown excellent antioxidant activity in several assays (Yang et al 2010), suggesting that it could inhibit degenerative change such as skin cancer, sun damage and the effects of ageing. Linalool, one of the major constituents of lavender oil, has shown very good in vitro activity against human basal cell carcinoma (Cherng et al 2007) and a topically applied 10% dilution of linalool reduced skin tumor incidence in mice by 33% (Gould et al 1987).

So today we can say that the principal known benefits of using lavender oil on the skin are that of numbing pain and healing wounds (cuts, sores, abrasions, ulcers), and other probable benefits include preventing bacterial colonization, treating fungal infections, combating blemishes, preventing skin cancer, and countering the damaging effects of UV radiation (photo-ageing).

“There is a conflicting research on just how much of a photosensitizer lavender can be.”

There is no conflict. Perhaps Paula Begoun does not know the difference between phototoxicity and photoallergy. She also seems to have confused allergic reaction with phototoxicity. I know, dermatology jargon can be very confusing! Lavender oil is not photosensitizing on the skin (Opdyke 1976 p451), and linalyl acetate is neither a photoirritant nor a photoallergen (Bickers et al 2003). This means that there is no risk of an adverse reaction in strong sunlight, as there is with bergamot and some other citrus oils.

There is one report of photoallergy to lavender oil (Goiriz et al 2007). This is the only case of photoallergy to lavender oil ever reported, and photoallergy from essential oils is so rare that it can be discounted as a risk. This is not only a non-issue, it’s also ironic, considering lavender’s protective action in relation to UV radiation damage.

“When exposed to oxygen (as it would be when applied to your skin), one of it’s fragrant components, linalyl acetate forms substances that lead to allergic contact dermatitis in and out of sunlight.”

Lavender oil contains two major constituents in approximately equal amounts – linalool and linalyl acetate. Oxidation is actually more of a problem with linalool than with linalyl acetate, and it’s true that, over a period of months or years, lavender oil constituents can oxidize to hydroperoxides. These “oxidation products” are often slightly more skin-allergenic than the original compounds (which are virtually non-allergenic). However, oxidation is a very slow process – it does not happen in a few minutes while a product is sitting on your skin! To avoid the possibility of oxidation, I recommend that products containing lavender oil also include an added antioxidant. This is in line with the International Fragrance Association recommendation that essential oils high in linalool should include an antioxidant, such as the addition of 0.1% alpha-tocopherol (IFRA 2009). Even without an antioxidant, the shelf life of a lavender-containing product should be good for at least 12 months, so long as the essential oils were reasonably fresh when first used.

“Because the fragrance constituents in lavender oil oxidize when exposed to air, lavender oil is pro-oxidant. This enhanced oxidation also increases its irritancy on skin.”

This is partly true. It’s important to realize that in these tests, the essential oil is typically exposed to the air every day for a period of weeks or months. This scenario does not reflect real-world use of lavender oil, though it does show that oxidation will happen eventually. But Paula Begoun is wrong to label lavender oil as a pro-oxidant – it is not, it is an antioxidant that can itself eventually oxidize. That does not make it a pro-oxidant! Pro-oxidants cause oxidation. And, she uses “irritation” here when she means “allergenicity.” They are not the same thing, and the hydroperoxides that can form in lavender oil are potentially allergenic, not irritant.

“Lavender leaves contain camphor, which is known as a skin irritant.”

This assertion smacks of desperation! Lavender oil contains less than 1% of camphor which, anyway, is only a mild irritant. If you have a product containing 1% lavender oil, then you will end up with less than 0.01% of camphor. Even if camphor was a powerful irritant, this would hardly be an issue.

“Research also indicates that other components of lavender, specifically linalool, can be cytotoxic, meaning that topical application causes skin-cell death.”

Here lies the fundamental claim of risk, which however is based on a fundamental misunderstanding. Lavender oil was cytotoxic to human dermal fibroblasts and endothelial cells (skin cells) in vitro at concentrations greater than 0.125%. Linalool (35% of the oil sample) had similar toxicity to the essential oil, while linalyl acetate (51% of the oil sample) was more toxic. Membrane damage was thought to be the mechanism of toxicity (Prashar et al 2004). In this type of assay, the test substance is in direct contact with isolated cells in a petri dish. Without that direct contact, cell membrane damage will not take place at those low dilutions. It’s an in vitro test, and you can’t assume that the same effect will happen when you apply lavender oil to the skin, because the skin has a protective barrier: the stratum corneum. However, even if you applied lavender oil to broken skin, it would still not be equivalent to the test using isolated cells, because the dermis is a complex matrix of tissue that contains those cells.

Any type of in vitro test is only suggestive of a possible effect. You can never assume that the same effect will take place in the living body. It might, it might not. Either the cytotoxicity described above will manifest as irritation, or it will be so negligible as to have no importance. The most telling evidence is the fact that lavender oil has been successfully used in wound healing at 4%, with no adverse effects. Dermatological testing also reveals a lack of irritation. In a 48 hour occlusive patch test on 50 Italian volunteers, undiluted lavender oil produced no adverse reactions. Similarly tested at 1%, it produced no reactions in 273 eczema patients (Meneghini et al 1971). Undiluted lavender oil was slightly irritating to rabbit skin, but was not irritating to mouse or pig skin; tested at 10% on 25 healthy volunteers it was neither irritating nor sensitizing (Opdyke 1976 p451). So if there is any cytotoxicity, it’s not significant.

“It is a must to avoid in skin-care products.”

Skin allergies to lavender oil do happen occasionally, and I know of five cases (not cited here) in the dermatology literature, reported between 1986 and 2000. Considering that it is the most widely used essential oil in aromatherapy (global annual production about 200 tonnes), lavender oil allergy is extremely rare. And, although it is a very low-risk skin allergen (possibly only when oxidized), it is not an irritant. Nor are rose, cedarwood and tangerine. Undiluted lavender oil can work wonders on stings and blemishes, but it should not be applied to large areas of skin simply because it has a drying effect, due to rapid evaporation – the same reason that alcohol is drying.

If you don’t want to use lavender oil – or essential oils in general – that’s fine. But please, don’t mis-represent the science just so you can justify your world-view! Paula is right to draw attention to the possibility of lavender oil oxidation, but this is not a major problem, and is easy to avoid. To be super-safe, use undiluted lavender oil within 12 months of purchase, keep it cool and away from strong sunlight, and add an antioxidant to any product containing it (not needed in soaps).

If you search for negative effects you will surely find them, and it’s easy to become enmeshed in that negativity. I submit that the dermal benefits of lavender oil outweigh the risks to a considerable degree.

References

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Sakurai H, Yasui H, Yamada Y et al 2005 Detection of reactive oxygen species in the skin of live mice and rats exposed to UVA light: a research review on chemiluminescence and trials for UVA protection. Photochemical & Photobiological Sciences 4:715-720

Soković M, Glamočlija J, Marin PD et al 2010 Antibacterial effects of the essential oils of commonly consumed medicinal herbs using an in vitro model. Molecules 15:7532-7546

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