Shelf life · 1 min read
How long does vitamin C serum last?
Quick answer: The average vitamin C serum lasts about 3 to 4 months after opening. Once it turns yellow, orange or brown, it has likely oxidized.
- Shelf life
- 3–4 months
- after opening
- Risk
- Low
- mainly loses effectiveness as it oxidizes
Signs your vitamin c serum has gone bad
How to store it
- Keep it away from heat and light, for example in a dark drawer
- Choose dark, opaque bottles and close them right after use
- Pumps expose the serum to less air than droppers
When does my vitamin c serum expire?
An estimate based on general guidance or your label. Always follow the product's own label, and replace anything that smells, looks or feels different.
Why vitamin C changes color
Vitamin C reacts with air and light. As it oxidizes, it turns from clear or pale to yellow, then orange, then brown. A dermatologist quoted by Skincare.com says that if it is completely yellow, brown, orange or any shade other than when you bought it, it has most likely gone bad.
Serums in general last longer
Many other serums are given 6 to 12 months after opening. Vitamin C is on the short end because the active ingredient itself is unstable. If you use it only now and then, a smaller bottle is less likely to go to waste.
Shelf life by type
| Type | Shelf life | Note |
|---|---|---|
| Vitamin C serum | 3–4 months | |
| Serums in general | 6–12 months |
FAQ
Is oxidized vitamin C harmful?
Mostly it just stops working as well. Stop using it if it irritates your skin.
Should I keep vitamin C in the fridge?
Skincare.com's expert suggests a refrigerator or dark drawer. Some brands prefer room temperature, so check your label.
This is general guidance compiled from the sources below. It is not medical advice. Always follow your product's label, and stop using anything that irritates your skin or eyes.
Sources
- How to Tell If Your Vitamin C Serum Has Gone Bad, Skincare.com by L'Oréal. Accessed September 24, 2026.
- How long does makeup last? Your guide to expiration, contamination and curation, MECCA. Accessed September 24, 2026.