---
title: "Does Hydrogen peroxide expire? Degrades in quality"
description: "It decomposes into water. An opened bottle is often plain water within six months. What actually changes over time, whether it matters, and how to store it."
url: https://atoneplace.net/does-it-expire/hydrogen-peroxide/
site: "At One Place"
---

# Does Hydrogen peroxide expire?

**Does Hydrogen peroxide expire?: It decomposes into water. An opened bottle is often plain water within six months.**

Unopened: 3 years. Opened: about 6 months

Hydrogen peroxide breaks down into water and oxygen, a reaction accelerated by light, heat, and contact with almost any metal or organic material — which is why it is sold in opaque brown bottles. Every opening introduces contaminants that catalyse it. The test is simple and genuinely works: pour a little into a sink and it should fizz vigorously on contact with the drain. No fizz means water.

## How to store it

- Original brown bottle, closed, in the dark.
- Never decant it into a clear container.

## How to tell it has gone

- The fizz test. If it does not bubble on skin or in a drain, it has gone.

> "Use by" and "best before" are legally different. Use-by is a safety date and should be respected; best-before is about quality, and food is usually fine well past it. Where the two diverge matters, the page above says which applies.

## Common questions

### Does Hydrogen peroxide expire?

It decomposes into water. An opened bottle is often plain water within six months.

### How long does Hydrogen peroxide last?

Unopened: 3 years. Opened: about 6 months

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## Sources

- US Food and Drug Administration — FDA (https://www.fda.gov/) [Public domain (US Government)]