Do makeup and tools expire or harbour bacteria?
Short answerYes. Makeup has a shelf life (mascara ~3 months, liquids 6–12, powders 1–2 years), and dirty brushes and sponges harbour bacteria that can cause breakouts and irritation. Clean tools regularly, replace sponges every few months, and never share or use store testers on bare skin.
Both products and the tools that apply them have limits — and hygiene is a real, not theoretical, concern.
Rough product timelines
- Mascara & liquid liner: ~3 months (eye-area, highest risk).
- Foundation/concealer: ~6–12 months.
- Powders: ~1–2 years.
Tool hygiene
- Brushes and sponges build up bacteria; clean on schedule and replace worn sponges.
- Never use in-store testers on your face — community threads are full of warnings about people swatching and returning products.
As one widely-upvoted comment put it, "there is no justifying opening a cosmetic product, using it then putting [it] back." Treat your tools and testers with the same hygiene you'd want from anyone sharing them.
What people actually say
Real, unedited voices from Reddit communities and verified Amazon.com reviews — cited, not paraphrased.
“There is no justifying opening a cosmetic product, using it then putting back, whether or not it's sealed.”
“A lot of makeup brands don't stick to dead skin — [funeral-home insight on how makeup behaves].”