How to Know If Your Vitamin C Serum Has Gone Bad

Vitamin C is a powerful antioxidant that helps protect skin from free radical damage and as a result, prevents signs of premature aging — like wrinkles — from forming. The ingredient is also known to target hyperpigmentation and helps even out skin tone for a brighter complexion. 

The one downside of vitamin C is that it’s unstable. This means that over time it can oxidize, degrade and lose efficacy. Factors like light, air, heat and humidity can all speed up the oxidation process, but how can you tell if your vitamin C serum has gone bad? We asked Dr. Elizabeth Houshmand, a Dallas-based, board-certified dermatologist and Skincare.com expert, to find out. Keep reading to learn if it may be time to toss your beloved vitamin C serum. 

How to Know if Your Vitamin C Serum Has Gone Bad

The biggest red flag is if the color of your vitamin C serum has changed over time. “If it is completely yellow, brown, orange or any shade other than what it looked like when you first bought it, it most likely has gone bad,” says Dr. Houshmand. If you’re still unsure, take note of any scent or texture changes, which may also be a sign that it’s time for a fresh one. While she says there’s no harm in using an oxidized vitamin C serum, you’re not going to be reaping its many benefits. 

How Can You Prevent Your Vitamin C Serum From Going Bad? 

“Your best option is to use the vitamin C product within a three-month time period,” she says, noting that the average vitamin C serum lasts for three to four months before it expires. “You can also keep your product away from heat and light,” she says. This is why we swear by keeping our vitamin C serums in the refrigerator. 

Choosing a vitamin C serum with a certain type of packaging can also help prolong the shelf life. Dr. Houshmand recommends looking for a dark, opaque glass bottle with a protective seal. Two that we like are the Kiehl’s Powerful-Strength Vitamin C Serum and the SkinCeuticals C E Ferulic. 

Another option is the L’Oréal Paris Revitalift Derm Intensives Vitamin C Serum, which is housed in an airtight metal tube to prevent exposure to oxygen and light. Pure vitamin C (also known as L-ascorbic acid) has been found to be more stable in powder form. Vitamin C powders, like the Neogen Real Vita C Powder Lemon can be mixed right into your favorite gentle toner or essence. 

Whatever form of vitamin C you prefer, using it before it oxidizes will help you achieve the glowy skin of your dreams. 

Photo: Chaunte Vaughn

Read More: 

Why SkinCeuticals C E Ferulic Is a Vitamin C Serum Worth the Money

6 Skincare Tips for Glowing Skin

Derm DMs: Can You Use Ferulic Acid As a Standalone Antioxidant (Without Vitamin C)?