Silver is known to have anti-bacterial properties and is used in many types of dressings for wounds, ulcers and burns.
How it exactly works is unknown, but silver is thought to stop microbes from spreading.
The amount of NHS cash spent on such products has risen from around 23 million in 2005 to around 25m in 2006-7, according to an editorial in yesterday's Drug and Therapeutics Bulletin.
In the article, experts said the evidence backing the use of silver dressings was not robust enough.
Trials on effectiveness have featured small sample sizes and have failed to assess how well the dressings work over a long period.
The article states that the high cost of the dressings is "difficult to justify" while evidence they work better than cheaper dressings is so scarce.