The online retail giant charged more for best-selling items compared to other shops, including Boots, Superdrug and Sainsburys.
The voucher codes surveyed a shopping basket of 20 current popular beauty products - amounting to £220.09 - and discovered that British women could be missing out on £56.67 worth of discounts if they don't shop around.
There were huge discrepancies in prices across Boots
, Sainsbury's and Amazon for a range of beauty essentials, including shower gels, beauty scrubs and shampoos.
According to the study, Dove, St Ives Apricot Scrub, Charles Worthington and Radox were the brands with products showing the largest price differences.
The difference in price was as much as 167 per cent, for example:
* Dove Nourishing Care shower oil: £2.48 at Superdrug to £6.59 at Amazon, 166 per cent increase
* St Ives Apricot Scrub: £2.05 at Superdrug – £5.25 at Amazon, 156 per cent increase
* Charles Worthington Volume & Bounce Shampoo: £5.99 at Boots to £13.95 at Amazon, 133 per cent increase
* Radox Feel Uplifted shower gel: 98p at Superdrug to £2.62 at Amazon, 167 per cent increase
But it wasn't all bad for Amazon as proved it was cheaper to purchase Bio Oil and Revlon Ultimate All-in-One Mascara from the other retailers.
It's also worth noting that the research was undertaken on one day in August.
And that some of the items - in particular those sold by Superdrug - were on promotion.
Retailers offer discounts and promotions on popular items making it hard for shopper to know where to buy the item they want at the lowest price.
An Amazon spokesperson declined to comment when approached by The Sun Online.
The average British woman spends £20 a month on beauty products and 53 per cent of them fail to regularly check prices.
Sezer Yurdakul, Global Head of Online Marketing at Voucherbox said stressed the importance of shoping around for beauty products.
He said: "There is no one shop stop for beauty lovers so it is vital you shop around in order to get the best deals - even on the low value products.
"It's always worth checking store offers which may make multiple purchases cheaper overall, as well as factoring in online vouchers and promotions - something which almost a quarter of shoppers do already.
, St Ives Apricot Scrub
, Charles Worthington