As mentioned above, our cells' production of hyaluronic acid starts to decline as we get older, so if you're looking for an intense boost for aging skin then Skinceuticals HA.Intensifier (£85) is worth considering. A nifty serum that boosts your own levels of HA. Dr Alexis Granite, consultant dermatologist at the Cadogan Clinic in London, describes it as having "an elegant texture and scent, plus it works!"