NOW (Bloomingdale, IL) recently tested 35 oregano oil supplements purchased from Amazon. Results showed that nearly two-thirds of the products failed potency testing and six had no detectable carvacrol, the active measurable component in oregano oil. In fact, many of the soft gel samples contained virtually no oregano smell or taste, according to NOW.

NOW purchased two bottles of each oregano oil supplement (including NOW brand) in February 2026 to conduct internal analysis. The company also partnered with Eurofins to ensure accuracy and transparency.

Oregano (Origanum vulgaris) is a popular aromatic herb whose oil is used to maintain healthy intestinal flora balance. The main active compound, carvacrol, is responsible for its beneficial properties and genuine oregano oils typically containing 55 to 90 percent carvacrol.

Carvacrol was quantified by HPLC (high-performance liquid chromatography) using a validated reverse-phase method. Non-specific methods can be fooled by other constituents of oregano oil like thymol. These methods may artificially inflate potency, making products seem compliant when they’re not, NOW stated.

A cursory glance also suggested many of the products were produced by the same companies, most likely as contract or private label manufacturers. Even when using a contract manufacturer, the responsibility of providing safe, quality products lies equally with everyone in the supply chain and testing should be perform at every step, NOW added.

In the past, NOW has carried out multiple tests on products from Amazon similar to this one. “This round of testing was disappointing, with nearly two-thirds of the brands failing carvacrol testing,” said Katie Banaszewski, senior director of quality at NOW. “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.”

For more information, visit www.nowfoods.com.