Makeup hygiene is a shelf-life problem, not squeamishness

Comparisons of makeup shelf life usually pick a winner. This one picks the circumstances, which is more useful.

Reading the symbols

The small open jar symbol with a number and the letter M indicates the period after opening, in months, that the manufacturer tested for. That figure assumes reasonable storage and use, not a product left open in a hot bathroom or carried loose in a bag.

Some products also carry a best before date, which applies to the unopened product on the shelf. Neither figure is a hard cliff, but both are based on stability and preservative testing rather than on guesswork. Writing the opening date on the base of a product with a marker is a small habit that removes all uncertainty later.

Which products need the most care

Mascara and liquid eyeliner have the shortest recommended lives, generally around three months, because of the eye and the wet environment. Liquid foundation, cream products and anything water-containing sit in the middle, often around six to twelve months. Powders contain little or no water and last considerably longer, though the binders and the surface can still degrade.

By the end of a working day, lipsticks and balms are anhydrous and stable, but they contact the mouth and pick up organisms with every use. Nail products degrade chemically rather than microbially, and thickening is the usual sign of age.

How contamination happens

Fingers introduce organisms into jars and pots, and wet fingers introduce water alongside them. Wands returned to tubes carry whatever was on the lashes or lips back into a warm, enclosed environment.

Storing products in a bathroom exposes them to repeated heat and humidity cycles that stress preservative systems. Sharing products transfers organisms between people, which is a genuine route for eye and lip infections. Testers in shops are the extreme version of all of these, and disposable applicators are worth insisting on.

Signs something has gone off

A change in smell is the most reliable early signal, particularly a rancid note in products containing plant oils. Separation that does not resolve on shaking, changes in texture, and colour shifts all indicate degradation. Powders that develop a hard glazed surface have accumulated sebum from brushes, which affects application rather than safety.

Any product that stings when it previously did not deserves to be discarded rather than persevered with.

Mould, which appears as spots or fuzz, means immediate disposal with no further consideration.

Storage that extends life

Cool, dry and dark is the whole principle, which means a bedroom drawer beats a bathroom shelf. Closing lids properly prevents both evaporation and contamination, and it matters more than people assume. Keeping products out of direct sunlight prevents both pigment fading and degradation of oils.

Under makeup, cars are the worst environment available, cycling between extremes of temperature repeatedly. Refrigeration is unnecessary for most makeup and can cause emulsions to separate.

If you are pregnant, breastfeeding or using prescription treatment, check specific actives with a doctor or pharmacist before adding them.

When to see someone

Redness, swelling, discharge or pain around the eyes or lips after using a product needs medical attention rather than a product swap. Recurrent styes or lid margin inflammation may relate to eye makeup habits and are worth discussing with a doctor or pharmacist.

Anyone who has had an eye infection should discard eye products used during it to avoid reinfection. Contact lens wearers have additional reasons to be careful about particles and expired products. Persistent irritation from cosmetics generally may reflect a contact allergy that clinical patch testing can identify.

Side by side

The takeaway

Write the opening date on the bottom and let the symbol decide rather than optimism.

Skin changes slowly. Anything promising otherwise is selling the promise.