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Anne Marie Helmenstine, Ph.D.

Hydrogen Peroxide Shelf Life

By July 9, 2013

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If you've ever poured hydrogen peroxide solution onto a cut and didn't experience the expected fizz, it's likely your bottle of hydrogen peroxide has become a bottle of plain water. The 3% hydrogen peroxide solution you can buy for use as a disinfectant typically has a shelf life of at least a year if the bottle is unopened, but only lasts 30-45 days once the seal has been broken. As soon as you expose the peroxide solution to air, it starts to react to form water. Also, if you contaminate the bottle (e.g., by dipping a swab or finger into the bottle), you can expect the effectiveness of the remaining liquid to be compromised.

So, if you have a bottle of hydrogen peroxide that has been sitting in your medicine cabinet for a few years, it would be a good idea to replace it. If you've opened the bottle at any point, its activity is long-gone. Good to know, right?


February 15, 2010 at 10:29 am
(1) Kam Fok says:

It is true potency of hydrogem peroxide solution is going down slowly. It is a good practice for writing the date on the bottle label when you open the bottle and start to use it.

February 16, 2010 at 10:26 pm
(2) Gideon says:

I know that glycerin is an inhibitor to the decomposition of hydrogen peroxide,can it be added to improve it storage life?

April 9, 2010 at 8:16 am
(3) Ruth says:

At home, wouldn’t it be simpler to just apply hydrogen peroxide to an object or area that is known to be contaminated with bacteria (to test it)?

If I pour a little down the bathroom sink drain, I always hear it fizzing down there.

August 13, 2011 at 8:43 am
(4) john says:

It doesn’t completely lose all of its zip that quickly, after two years I have used an opened bottle to apply a bit of it to a rash (between thighs from walking) and felt the sting of it as it disinfected the chafed area

November 1, 2011 at 11:55 am
(5) aj says:

to say that shelf life reacting to 1ml of air or tons of air is the same 30-45days is rediculous, if u break the seal & 1ml of air gets in & is reasealed (capped tight) It will last for at least 10times that. Its easy to test pooring it on something anyone can see.

November 16, 2011 at 6:50 pm
(6) Kiran says:

hey kid, whats up? u guys ever talk about anything but school, come on man, i’m a high school student too, 9th grade. Anyways aj i think ur right it can last for at least 10times that.

November 16, 2011 at 6:56 pm
(7) Kiran says:

fire and ice
some say the world would end in fire, some say in ice from what i’ve tasted if desire i hold with those who favor fire, but if i had to perish twice, i think i know enough of hate to say that for distraction,
is also great

this is a poem from eclipse, (the twilight saga)

March 2, 2012 at 7:12 pm
(8) Jim says:

I’m no expert, nor a scientist. From experience, I can tell you that a bottle of 3% hydrogen peroxide, purchase long ago and opened at least 4 years ago, is still effective in removing blood stains from clothing & rugs…just did it last week. I’m not trying to be cheap, it’s just the only bottle I had, and I didn’t have time to get a new bottle before the stains set. I suspect that the earlier comment about rapid decomposition, once opened, is correct IF THE TOP IS NOT QUICKLY AND FIRMLY REPLACED.

…But I’m going to get a new bottle today.

March 2, 2012 at 7:17 pm
(9) Jim says:

Hey “Kiram”, do your homework. That poem, Fire and Ice, was written by Robert Frost, and you mis-quoted it — “Some say the world will end in fire,
Some say in ice.
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.”

May 2, 2012 at 11:28 am
(10) Greg P. says:

I recently applied some peroxide from a 2 year old bottle (previously opened) to a paper cut on a finger. When I removed the Band-Aid a couple of days later, there was a white film on the area. Plain water would not leave this film so I suspect the peroxide WAS still active, although perhaps weakened. 30-45 days ? I don’t buy that.

December 1, 2012 at 3:11 am
(11) Ben says:

Peroxide bought from a store or pharmacy has many chemical stabilizers added to it, which make it unsafe to digest but also make it last a lot longer.

When you open a bottle of hydrogen peroxide, and leave the cap OFF, or loose enough it might as well be off, it will indeed become a bottle of water in 45 days.

Putting the cap back on correctly and storing in a dark, cool place will increase the shelf life dramatically once opened, and it’s much longer than 45 days.

February 4, 2014 at 4:08 am
(12) Travis says:

Sometimes it can last a lot longer. I just used some from an open bottle that’s been open for months, and it fizzed really well and did the job.

It’s funny how that works.

February 7, 2014 at 2:09 am
(13) Bill says:

I buy the plastic bottles & when I use some, I squeeze the bottle to remove as much air as possible & tighten the cap to keep air out which extends the life indefinitely.

February 9, 2014 at 1:38 am
(14) bruce says:


After a reaction to neosporin I found a bottle of 3% hydrogen peroxide(in the back of our bathroom cabinet) that was 25%(approx) full and >10 years old, I tried it, and it fizzled and stung and the reaction has sub-sided.. so there was still some efficacy left….

February 11, 2014 at 4:26 pm
(15) Nick says:

I find idea that H2O2 expires quickly to be false, i tested some 3% H2o2 in titration, and 13 years after its expiration date it was still at .5% H2O2 content

February 26, 2014 at 5:24 am
(16) The dude says:

I am a chemist and I am correct to say that all these people have discovered the many uses of water.

Water can disinfect
Water can remove stains
Water ( unless triply distilled) can deposit residue upon evaporation
And store bought h2o2 is mostly water to begin with.

As for the bubbling and stinging people report… I don’t remember h2o2 ever stinging anything.

If you open the bottle the stuff starts to decompose. However oxygen is required so screw the lid on tight and don’t leave the cap off. You should get your 4$ worth out of a bottle. After 12 months, THROW it AWAY! That’s just gross

April 14, 2014 at 2:50 pm
(17) Woah1 says:

Woah everyone. It’s ok.

Thanks for the comments everyone. You guys have been a great help. Really! It answered my question.

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