I don’t buy beauty products in January. I try not to buy anything except food, travel and other essentials. But I do have a good sort out and a reorganisation of all my beauty supplies.

First, I audit what I have and get rid of anything opened that’s past its best. Manufacturers’ advice may vary, but I apply the following rules of thumb: open skincare lasts about a year; and change of colour isn’t necessarily the death knell, but a change in texture (if the products splits, thins or becomes crystallised) or smell (skincare that’s gone off has a distinctive whiff), signals The End.

Some active ingredients lose some potency over time, though this is more easily avoided than it used to be, thanks to advances in cosmetic science. The contents of pipette/dropper bottles or open jar packaging will often go off faster than something in an airless pump. Wet products such as lotions, creams and gels have a much shorter life expectancy than dry powders, which last for ages (truly, I still own eyeshadows I wore to acid house raves).

If powder products develop a greasy film over their surface, gently scrape it away with a sharp knife. What lies beneath is likely to be fine. Ditto, pencils. Sharpen and crack on unless something seems off.

For open foundation, primer and concealer, you’re looking at a year’s use at most. Lipsticks and glosses, a couple of years, perhaps longer if you sanitise the bullets or doe-foot sponge applicators, respectively. Mascara needs to be opened and used up: no popping in the cupboard for best – you have three to six months, max. Things high in alcohol such as hairspray, hand sanitiser and makeup setting spray are the Olivia de Havillands of beauty – all enjoy exceptionally good innings. Unopened product is mostly good for three or four years, but I find “Clean beauty” products, ie those not containing traditional and well tested preservatives such as parabens, can have the staying power of Liz Truss.

I then reorganise the survivors into satisfying rows of Muji’s PP containers (from £2.50) and label them with my Dymo label machine (any excuse). I strongly recommend it.

If you find new and unopened toiletries you are unlikely to use, drop them into your local food bank or consider donating to a hygiene poverty charity, such as Beauty Banks, which – full disclosure – I co-founded and run on a voluntary basis. We have donation bins in over 100 branches of Superdrug and your support will matter to someone.