It’s a truth universally acknowledged that all good things must come to an end. Brangelina, Breaking Bad – even Bake Off with its gloriously kitsch new format won’t last forever. This, of course, is upsetting; nobody likes change. But for beauty devotees the world over, it’s even more distressing to know that this age-old adage can also be applied to skincare. I hate to be the bearer of bad news but the effects of your fancy serum do not last forever. It’s not actually the serum’s fault. It tried its darned best. The real perpetrator? Your skin. “Your fibroblasts are really similar to your muscles. If you continuously do the same cardio and weights routine, your muscles get bored quickly and build up a resistance. The same goes for your skincare. Skin cells get used to the effects of the ingredients and they quickly become bored and unresponsive,” explains cosmetic dermatologist, Dr. Frances Prenna Jones