Gold standard consumer rights group Which? warned shoppers that Black Friday sales offer few real deals.
In a new report, it said that most goods were cheaper or available for the same price at other times and just one in 20 offers were cheaper during the annual sales.
Which? home products and services chief Natalie Hitchins said: “We have repeatedly shown that deals touted by retailers on Black Friday are not as good as they seem. Time-limited sales can be a good opportunity to bag a bargain, but don't fall for the pressure tactics around Black Friday.
"Our investigation indicates that this popular shopping event is all hype and there are few genuine discounts."
Hitchins suggested shoppers try to steer away from impulse buys and do their research before stumping up the cash for goods in the Black Friday sales.
Which? looked at 83 products on Black Friday last year and monitored prices six months before and after he date. It identified key product types that were cheaper outside Black Friday sales — such as smart speakers, tumble dryers as well as coffee makers.
It found that that only four of the 84 products, from major retailers including Amazon (AMZN), John Lewis, and Currys PC World, were cheaper on other days of the year.
Prior to last year’s Black Friday event, only six in 10 items were cheaper or the same price on at least one day in the six months.
Retailers hit back at the report, with Amazon saying: "Our Black Friday sale is about thousands of deals on a huge selection of products from every category across the site, at a time of year when we know saving money is important to our customers.
"And the best thing about shopping online is that customers can easily compare prices, allowing them to make an informed purchase decision.”
John Lewis added: "In addition to the variety of offers we have in-store and online during the Black Friday period, our commitment to being 'Never Knowingly Undersold' means that we continuously monitor and match the prices of our high street competitors throughout the year."
Currys PC World said: "Our customers tell us that they appreciate the increased choice during Black Friday where we have the most deals on at once. When we launched our Black Friday event last year, 40% of those products were the lowest price they had ever been."