How To Tell If Your Vitamin C Serum Has Gone Bad

Vitamin C serums are great at reducing the appearance of fine lines, wrinkles, dark spots, and acne by promoting the synthesis of collagen to help skin heal faster. But if your serum has begun to break down and expire, its efficacy will decrease, rendering the product useless over time. To help you get the most out of your skin-care products, learn how to tell if your vitamin C serum has gone bad.

Texture

Take note of what the original texture of your serum was, as different textures are common among brands. If a vitamin C serum has gone bad, the texture can change and become sticky, grainy, or even thin out. Any sudden shift in texture from its original form is an indication that your serum has gone bad.

Smell

Some vitamin C serums have fragrance added, while others may have no scent added at all. Some people liken the smell of the serums to bologna or hotdogs. However, your vitamin C serum should never have a sour or tangy smell to it. If the smell has suddenly changed or a new sour smell has formed, the serum has likely gone bad.

Color

The easiest way to tell if your vitamin C has gone bad is to look at the color. Most serums will be white or clear, but if the serum has begun to oxidize, the color will darken. At first, oxidation will make your serum look yellow, but at this stage, it’s still safe to use and effective. After the yellowing stage, the serum can become a dark brown or deep burnt orange. At this stage, the product is ineffective and can cause irritation if used.

What To Do

So how can you prevent your serum from going bad? The first thing you should know about vitamin C is that it comes in different formulas, with some being more stable than others. Magnesium ascorbyl phosphate (MAP) is the most stable version of vitamin C.

While vitamin C is sensitive to light, heat, and air, the MAP formulation is the least affected by these environmental factors. However, overall, it’s best to store it in a cool dark place. You can keep it in the box, store it in your medicine cabinet, or put it in a skin-care fridge, but never leave your serum open and exposed to air.

Ultimately, the best way to tell if your vitamin C serum has gone bad is to take note of any rapid changes in the product. If you notice these changes, it’s best to throw away the product and, in general, avoid applying any expired products to your skin.