Is It Safe To Use Expired Hydrogen Peroxide?

Hydrogen peroxide is probably a staple in your household cleaning supplies or first aid kit, but do you replace your bottle regularly? If not, your hydrogen peroxide may have expired without you even knowing.

The shelf life of 3 to 7 percent hydrogen peroxide solution purchased from your local store is around three years for an unopened bottle (via Healthline). It is much shorter after the bottle is opened, though, with a shelf life ranging one to six months. The decay rate for a 3 percent hydrogen peroxide solution is estimated to be at 0.5 percent per year, according to ThoughtCo.

How does this happen so quickly, and why? Essentially, hydrogen peroxide starts to break down into water and oxygen gas after exposure to the air or to other contaminants like your finger or a swab. 

This can be frustrating when you need your bottle as a disinfectant or stain remover immediately. That leads to the main question you ponder while in your bind — is it still safe to use expired hydrogen peroxide? 

Hydrogen peroxide past its expiration date isn't harmful; however, its efficacy has been compromised as more time has passed by, according to Healthline. Even an expired, sealed bottle is no longer full-strength hydrogen peroxide. In fact, it is probably just plain water. But you should still use caution with expired hydrogen peroxide, as it can be a skin irritant and poisonous when consumed.

You can test if your hydrogen peroxide is still effective by pouring some into the sink — if it fizzes or bubbles, it's still effective. No fizz means it's a no-go and it's time to replace your bottle. 

Some tips to keep your hydrogen peroxide from losing its fizz are to store it in a cool, dark place and in its original dark bottle. You should also avoid opening your bottle until ready to use it, or try to buy in smaller portions so you are able to use it quickly enough. However, if your bottle of hydrogen peroxide is expired and no longer effective, you can just throw it out.