One of the industry's best-kept secrets, serums are fast becoming the new darling of women around the country - thanks to a little Boots number that is rapidly flying off shelves nationwide.

Sales of No7 Protect & Perfect Serum increased by nearly 2,000%, with 13 being sold every minute, after it was touted by the BBC Horizon programme as a 'wonder cream' that reduces wrinkles.

But beauty insiders aren't too surprised by the sudden popularity of serums.

Dr Barry Cohen, founder of pH Advantage, says: "The molecules in a serum are smaller than that of a traditional moisturiser, and therefore, are able to absorb more effectively into the skin's pores."

Concentrated ingredients are packed into a serum, which can penetrate the skin much quicker and more deeply for an intensive treatment. They can also help to address certain skin problems, such as dehydration and dullness.

To get a serum's full benefits, you should add a drop onto cleansed skin before applying your moisturiser in the morning, and again before you sleep at night.

Boots No7 skin-firming and complexion-brightening Protect & Perfect Serum, £17, was scientifically shown to repair photo-aged skin and improve fine wrinkles on the programme.

But it's not the only serum on the market that's been proven to boost the appearance of skin.

Alpha-H a-c-e kit, £60 at John Lewis, QVC and Hqhair.com, contains three vitamin serums. These pure forms of vitamins support, nurture and bolster skin better than other treatments. Alpha A helps reduce the appearance of lines and scars, Vital C firms and protects the skin, and Alpha E gives extra hydration.

Serums are successful in anti-ageing. Elemis' new Pro-Collagen Quartz Lift Serum, £95 or 143 Euros (01278 727 830/www.elemis.com), lifts and firms skin, while Lancome High Resolution Collaser-48 serum, £49, boosts collagen to slow down the signs of ageing.

Vitamin C is a popular ingredient, with pH Advantage High Potency Effective C serum, £70 or 103 Euros from Harvey Nichols, and Darphin Arovita C Line Response Firming serum, £45 or 75 Euros (0870 034 2566), including it in their formulas.

Not to be outdone, REN has launched two new anti-ageing serums - Revivo-Lift Radiant Day, £40, and Revivo-Lift H11 Night, £46 (0845 225 5600). Both claim to smooth lines and correct skin tone.

Malin+Goetz Replenishing Face Serum, £50 at Hqhair.com, is made without artificial colour or fragrance, and can be used on its own as an oil-free moisturiser, or an intensive booster for drier skins.

And Origins Modern Fusion, £27.50 or 42.50 Euros, contains rice. Inspired by an ancient Asian tradition, the rice butter hydrates, while purple rice protects.

Ensure your eyes don't reveal your true age with Darphin Lifting And Firming serum, or Dark Circles Relief And De-Puffing serum, £44 or 57 Euros each, or Lancome High Resolution Yeux Collaser-48, £37.

But you don't have to spend a fortune to look better, as the No7 serum proves. The Sanctuary Line Smoothing Serum, £9.95 at Boots, is reported by 77% of testers to be effective in smoothing wrinkles and fine lines.

Serums are also potent little products in hairland. Applied drop by drop, they can transform extremely damaged hair into silky, healthy and strong locks. A bottle of serum is sold every 20 seconds, proving that actions speak louder than words.

John Frieda caused a revolution when he launched his hair serums 20 years ago. The Frizz-Ease serum has miraculously tamed all degrees of frizz and led Vogue to declare John as the "founding father of modern hair-styling products".