Photo: OlgaMiltsova/Thinkstock

Spring is here—and the change in season may have you switching up your skincare routine. But if you're digging out last year's lightweight moisturizer, check the expiration date. Most opened products lose their effectiveness after one year and some even sooner, according to cosmetic chemist Ni'Kita Wilson. Expired products may not only lack potency, but could also cause an adverse skin reaction. If you're unsure how old something is, the general rule is to toss anything that has significantly changed in color or odor, or separated, clumped, thickened or thinned, says cosmetic chemist Mort Westman. All are signs that the product has gone bad. To be completely sure it's time to let go, here's a complete list of how long to keep your skincare products.

Moisturizer

Unopened: Two to three years

Opened: Up to one year

Photo: Jacob Wackerhausen/Thinkstock

Sunscreen
Unopened: Two to three years

Opened: Six months to one year

Photo: IngaIvanova/Thinkstock

Treatment Products (such as facial serum, retinoids, AHAs or Vitamin C) in A Pump or Tube
Unopened or Opened: No longer than one year

Photo: merznatalia/Thinkstock

Treatment Products in A Jar
Unopened: No longer than one year

Opened: Up to six months

Photo: Purestock/Thinkstock

Masks
Unopened: Two to three years

Opened: Up to one year*

*For cream or gel masks. Clay masks tend to dry out once opened, so they may last only six months.