Takeaway: Testing Oregano Oil Supplements on Amazon
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Bloomingdale, IL—For years, NOW has shared results from its industry quality testing program, which investigates unfamiliar brands sold on online in an effort to raise awareness on low-quality products in the marketplace. The focus of the latest round: Oregano Oil supplements purchased from Amazon.com.
As NOW explained, oregano (Origanum vulgaris) is a popular, aromatic herb, the oil of which is used to help maintain healthy intestinal flora balance. Carvacrol, the main active compound, is credited with the beneficial properties. Genuine oregano oils typically contain 55% to 90% carvacrol, NOW shared, adding: "Ensuring supplements contain genuine, properly standardized oil is essential for product quality and effectiveness."
About NOW's testing of oregano oil
NOW purchased two bottles of each Oregano Oil supplement (including NOW brand) in February 2026 to conduct internal analyses. To ensure accuracy and transparency, NOW also partnered with Eurofins, an ISO 17025-accredited independent laboratory. Carvacrol was quantified by HPLC (High-Performance Liquid Chromatography) using a validated reverse-phase method.
What the Testing Found: Widespread Potency Failures
- Out of 35 tested brands, only 14 met the label claim for carvacrol.
- 15 brands had less than 8% of label claim and 6 of those had no detectable carvacrol. NOW Oregano Oil liquid and softgels were among the few samples that met the label claim for carvacrol.
- Nearly two-thirds of the products failed potency testing.
- Six had no detectable carvacrol, the active measurable component in oregano oil.
- Many of the softgel samples contained virtually no oregano smell or taste, according to NOW, which the company said would be a red flag for consumers.
A chart detailing the results can be accessed on NOW's website.
NOW's observation about the results
“This round of testing was disappointing, with nearly two-thirds of the brands failing carvacrol testing,” said Katie Banaszewski, NOW Senior Director of Quality. “NOW’s in-house analytical testing paired with Eurofins’ independent verification underscores the importance of scientifically valid methods. NOW will continue to purchase and test products sold on major online platforms and publicly share the results to encourage higher quality standards across the supplement industry.”
Why Carvacrol Matters in Oregano Oil
The company maintains that choosing the correct testing method is key, explaining: "Choosing the correct testing method for carvacrol is critical. Non-specific methods, such as spectrophotometric assays, can be fooled by the other constituents of oregano oil, like thymol. These methods may artificially inflate potency results, making products seem compliant when they are not. In contrast, HPLC can separate and identify carvacrol from closely related compounds, providing an accurate and reliable measure of product quality. NOW’s and Eurofin’s testing both relied on chromatographic specificity, ensuring confidence in the results."
NOW added that there many be a commonality among the products: "A cursory glance at these products suggested that many were produced by the same companies, most likely as contract/private label manufacturers. Even when manufactured by a contract manufacturer, the responsibility of providing safe, quality products lies equally with everyone in the supply chain and rigorous testing should be performed at every 'link' in that chain."
Previous NOW testing includes:
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NOW also has reported multiple supplements sold on Amazon impersonating the NOW brand, as well as another prominent industry supplement brand.
Opportunity for natural products retailers
NOW generally does not test health food store brands or practitioner brands, as the company says quality issues do not seem to be a major issue with those brands. In 2022, WholeFoods Magazine recognized NOW and other industry leaders for their industry self-policing efforts, naming the Person of the Year: The Amazon.com Quality Activists. Dan Richard, VP of Global Sales and Marketing, NOW Health Group, told WholeFoods: “Stores can publish NOW’s results to let consumers know ‘buyer beware.' They can share some of the many articles published about our testing programs in their newsletters or on social media. The low prices online are sometimes too good to be true. Local stores have many advantages that online stores can’t offer including service, in-person experience, sampling, and more. It’s not easy these days for any business, but many natural retailers still succeed by finding a worthwhile niche, providing quality health products and at a reasonable price."
Related: The Natural View: NOW's Commitment to Supplement Quality & Transparency
- Concerns around adulteration in the supplement industry, and how NOW’s in-house testing helps protect against these issues.
- Some of the challenges labs face in maintaining rigorous standards, and how NOW deals with these challenges.
- Key takeaways from NOW Foods' testing of supplements sold on Amazon.
- ..and more.
FAQ: Oregano oil quality control
Q: What is the key active ingredient in oregano oil? Carvacrol is the primary active compound and is responsible for oregano oil’s functional benefits.
Q: What percentage of carvacrol should oregano oil contain? High-quality oregano oil typically contains about 55%–90% carvacrol, according to NOW.
Q: Why do some oregano oil supplements fail testing? NOW says inaccurate testing methods, poor manufacturing practices, or mislabeling can lead to inflated claims or low actual potency.
