What Is Carvacrol? The Compound Behind Oregano Oil's Strength

Pure carvacrol and undiluted oregano essential oil irritate skin, eyes and the lining of the mouth. Use only products labeled for internal use if you plan to swallow them, and avoid concentrated oregano oil during pregnancy and in young children unless a clinician says otherwise.

What is carvacrol?

Carvacrol is a phenol built on the same carbon skeleton as cymene, a compound common in herb oils. Chemists group it with the monoterpenoids, the family of small fragrant molecules that give many herbs their smell. Its formula is C10H14O. Thymol has exactly the same formula; the two are isomers, differing only in where the hydroxyl group sits on the ring (PubChem).

Carvacrol occurs in the essential oils of oregano (Origanum vulgare), thyme and several other plants (Sharifi-Rad et al., Phytotherapy Research, 2018). Outside the supplement aisle, it is used in small amounts as a food flavoring and preservative and as a fragrance in cosmetics (Suntres et al., Critical Reviews in Food Science and Nutrition, 2015). FDA includes carvacrol on its list of flavoring substances permitted in food (21 CFR 172.515), and oregano (Origanum) essential oils appear on its list of essential oils generally recognized as safe for flavoring use (21 CFR 182.20). Flavoring amounts are tiny compared with a supplement serving.

How much carvacrol is in oregano oil?

There is no single answer, because "oregano" is not one uniform plant. Researchers who analyzed 502 individual Origanum vulgare plants from 17 European countries found that the plants' essential oil content ranged from 0.03% to 4.6%, and that they split into distinct chemical types. Plants from Mediterranean climates tended to make cymyl compounds (the group that includes carvacrol and thymol), while plants from continental climates leaned toward other compounds such as sabinene (Lukas et al., Phytochemistry, 2015).

Even within one subspecies the chemistry shifts. Wild O. vulgare ssp. hirtum collected at three sites in southern Italy produced three different oils: one led by carvacrol and thymol, one led by thymol and alpha-terpineol, and one led by linalyl acetate and linalool (De Martino et al., Molecules, 2009).

Other plants make carvacrol too. Twenty-two samples of Thymbra capitata oil from Portugal all tested between 60% and 66% carvacrol (Salgueiro et al., Planta Medica, 2004). And not everything called oregano is Origanum: in FDA's spice list, the name also covers Mexican oregano, which comes from Lippia species (21 CFR 182.10).

The practical takeaway: two bottles labeled "oregano oil" can contain very different amounts of carvacrol. A stated percentage on the label is the most useful number you have.

What "70% carvacrol" or "80% carvacrol" means on a label

A carvacrol percentage usually refers to the oregano essential oil inside the product, not to everything in the bottle. Many liquid oregano supplements, Oreganol P73 among them, blend the oregano oil into a carrier such as olive oil, so the bottle as a whole is far less than 80% carvacrol.

So read two numbers together. A label that says "30 mg, 80% carvacrol" is most likely telling you how much oregano oil is in a serving (the milligrams) and how rich that oil is in carvacrol (the percent). The serving size on the supplement facts panel tells you how many drops or softgels deliver that amount. A higher percentage means a more concentrated oil, which also means more potential for irritation.

What does P73 mean on Oreganol labels?

Oreganol P73 is a product name used by North American Herb & Spice for its wild oregano oil, sold as a liquid and as softgels. The brand's listing describes the oil as wild oregano oil blended with extra virgin olive oil. We could not find "P73" defined as a carvacrol percentage or as any standard grade in scientific or FDA references, so it can't be compared directly with a figure like "80% carvacrol." If carvacrol content matters to you, check the current label or ask the maker. We mention the brand only because we carry it; this isn't an endorsement.

What does carvacrol do? The lab research

Most of what we know about carvacrol comes from cell cultures and animals. Reviews describe antibacterial, antifungal, antioxidant, anti-inflammatory and anticancer effects in these settings (Suntres et al., 2015; Sharifi-Rad et al., 2018).

The antimicrobial effect is the best understood. Carvacrol is fat-loving and carries a free hydroxyl group on a phenol ring, a combination that lets it slip into microbial membranes and make them leak (Sharifi-Rad et al., 2018). In one study, yeast cells exposed to a carvacrol-rich oil quickly took up a dye that only enters damaged cells, pointing to direct membrane injury as the way it killed them (Salgueiro et al., 2004). Lab work has shown activity against food-poisoning bacteria such as E. coli, Salmonella and Bacillus cereus.

Carvacrol also acts on human cells directly. It is a strong activator of two ion channels, TRPA1 and TRPV3, which are part of how the body senses its surroundings (PubChem).

What human studies show

Very little. A 2018 review concluded that human trials of carvacrol were still missing, and that this gap blocks any firm conclusion about clinical use (Sharifi-Rad et al., 2018).

The study most often cited for oregano oil in people is small. Fourteen adults whose stool tests showed intestinal parasites took 600 mg of emulsified Mediterranean oregano oil daily for six weeks. Afterward, Blastocystis hominis was no longer found in eight of them, and two other parasites cleared in the few people who had them (Force et al., Phytotherapy Research, 2000). There was no placebo group, and the study has not been repeated in a controlled trial. It's a reason for curiosity, not proof.

If you want to compare oregano oil with other popular oils, our guide to oil of oregano with black seed oil lays out the evidence for each side by side.

Carvacrol and oregano oil safety

• It's an irritant. Chemical safety filings classify carvacrol as irritating to skin and eyes, able to cause skin allergy, and harmful if swallowed in pure form (PubChem). Undiluted oregano oil can burn skin and the inside of the mouth.
• Dilute anything that goes on skin. Mix essential oil into a carrier oil and test a small patch first.
• Swallow only oral products. Choose supplements labeled for internal use and stay within the serving size.
• Mint-family allergy. Oregano and thyme are in the mint family, and people allergic to one of these herbs may react to others (Benito et al., Annals of Allergy, Asthma & Immunology, 1996).
• Pregnancy and children. We found no safety research supporting concentrated oregano oil in pregnancy, breastfeeding or young children, so avoid it then unless your clinician advises it.

Find it at William's

We carry several forms of oregano oil, so you can pick by how you plan to use it:

• Natural Factors certified organic oil of oregano liquid, 2 fl oz (30 mg, 80% carvacrol): the one product here with a carvacrol percentage on our listing, useful if you want a known strength.
• Natural Factors oil of oregano softgels, 180 mg (60 count): a softgel for people who don't want the taste of the liquid.
• North American Herb & Spice Oreganol P73 liquid, 1 oz: wild oregano oil in extra virgin olive oil, taken by the drop.
• Now organic oregano oil (essential oil), 1 oz: pure Origanum vulgare essential oil for diluting, diffusing or making your own skin blends.

Our main guide to oil of oregano covers everyday uses, and if you are curious about thymoquinone, the comparable compound in black cumin, see our black seed oil guide.

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