Countless generations have used the relaxing aroma of English lavender oil as a sleeping aid at home. But there has been a recent increase in reports of the traditional remedy no longer working, prompting a natural essential oil supplier to test some of those being sold online.

This found unscrupulous suppliers, particularly from China and India, have been using cheaper oils and artificial fragrances to bulk out their products and undercut pure lavender essential oil products, as these are in high demand and relatively expensive.

Now natural products tested 28 popular products sold on Amazon US and marketed as “Lavandula angustifolia” - English lavender or “pure lavender essential oil”.

They were subjected to chemical analysis to investigate whether they complied with the ISO standard for lavender oils. It found just three were authentic Lavandula angustifolia essential oil and showed no evidence of adulteration.

Eleven (55%) showed profiles inconsistent with authentic Lavandula angustifolia and appeared to contain lower-grade lavender materials, blended lavender-type oils, or non-authentic lavender species.

Twelve (60%) showed evidence of dilution with carrier oils, mineral oil-type substances, fatty esters, or other extender materials. Thirteen (65%) contained synthetic fragrance-related compounds or compositional patterns not expected in genuine lavender essential oil

Some of the “fake” products tested are listed high up on Amazon’s UK site too.

Now natural products said: “Several samples showed severe suppression of natural lavender constituents, while others appeared to be heavily formulated fragrance blends rather than true essential oils.

“Notably, eight of the tested brands are from China, and four are from India. Of these foreign brands, all failed testing due to the criteria above. Additionally, imported brands were four of the top five lowest-priced products.

“This analysis revealed that buyers should beware: the lowest-cost lavender oil products tested were the lowest quality.”

An Amazon spokesperson said: “We require all products offered in our store to comply with applicable laws, regulations and Amazon policies.

“We continuously monitor our store, and we take action to maintain a trustworthy selection for our customers, including removing noncompliant products, and outreach to sellers, manufacturers, and government agencies for additional information, when appropriate.

“We are in the process of removing the products in question.”