I’m sure most people have heard of hydrogen peroxide. It’s used as a disinfectant and, even if you’ve never used it for that, you probably at least know that it’s used to bleach hair. It’s where the phrase “peroxide blonde” comes from, after all. Hydrogen peroxide, and its formula, is so famous that there’s an old chemistry joke about it:

(I have no idea who to credit for the original drawing – if it’s you, leave me a message.)
To save you squinting at the text, it goes like this:
Two men walk into a bar. The first man says, “I’ll have some H2O.”
The second man says, “I’ll have some H2O, too.”
The barman brings the drinks. The second man dies horribly.
Now I think about it, it’s not a terribly funny joke.

Hydrogen peroxide has an extra oxygen atom in the middle.
Never mind. You get the idea. H2O2 (“H2O, too”) is the formula for hydrogen peroxide. Very similar to water’s formula, except with an extra oxygen atom in the middle. In fact, naturopaths – purveyors of alternative therapies – often refer to hydrogen peroxide as “water with extra oxygen”. But this is really misleading because, to torture a metaphor, that extra oxygen makes hydrogen peroxide the piranha to water’s goldfish.
Water, as we know, is pretty innocuous. You should try not to inhale it obviously, or drink more than about six litres in one go, but otherwise, its pretty harmless. Hydrogen peroxide, on the other hand, not so much. The molecule breaks apart easily, releasing oxygen. That makes it a strong oxidising agent. It works as a disinfectant because it basically blasts cells to pieces. It bleaches hair because it breaks down pigments in the hair shaft. And, as medical students will tell you, it’s also really good at cleaning up blood stains – because it oxidises the iron in haemoglobin to Fe3+, which is a pale yellow colour*.

Dilute hydrogen peroxide is readily available.
In its dilute form, hydrogen peroxide is a mild antiseptic. Three percent and even slightly more concentrated solutions are still readily available in high-street pharmacies. However, even these very dilute solutions can cause skin and eye irritation, and prolonged skin contact is not recommended. The trouble is, while it does destroy microbes, it also destroys healthy cells. There’s been a move away from using hydrogen peroxide for this reason, although it is still a popular “home” remedy.
More concentrated** solutions are potentially very dangerous, causing severe skin burns. Hydrogen peroxide is also well-known for its tendency to react violently with other chemicals, meaning that it must be stored, and handled, very carefully.
All of which makes the idea of injecting into someone’s veins particularly horrific.
But this is exactly what some naturopaths are recommending, and even doing. The idea seems to have arisen because hydrogen peroxide is known to damage cancer cells. But so will a lot of other dangerous substances – it doesn’t mean it’s a good idea to inject them. Hydrogen peroxide is produced by certain immune cells in the body, but only in a very controlled and contained way. This is definitely a case where more isn’t necessarily better.
The use of intravenous hydrogen peroxide appears to have begun in America, but it may be spreading to the UK. The website yestolife.org.uk, which claims to empower people with cancer to “make informed decisions”, states “The most common form of hydrogen peroxide therapy used by doctors calls for small amounts of 30% reagent grade hydrogen peroxide added to purified water and administered as an intravenous drip.”
30% hydrogen peroxide is really hazardous stuff. It’s terrifying that this is being recommended to vulnerable patients.
Other sites recommend inhaling or swallowing hydrogen peroxide solutions, both of which are also potentially extremely dangerous.

If anyone ever suggests a hydrogen peroxide IV, run very fast in the other direction.
In 2004 a woman called Katherine Bibeau died after receiving intravenous hydrogen peroxide treatment from James Shortt, a man from South Carolina who called himself a “longevity physician”. According to the autopsy report she died from systemic shock and DIC – the formation of blood clots in blood vessels throughout the body. When her body arrived at the morgue, she was covered in purple-black bruises.
Do I need to state the obvious? If anyone suggests injecting this stuff, run. Run very fast, in the other direction. Likewise if they suggest drinking it. It’s a really stupid idea, one that could quite literally kill you.
* As anyone who’s ever studied chemistry anywhere in my vicinity will tell you, “iron three is yellow, like wee.”
** The concentration of hydrogen peroxide is usually described in one of two ways: percentage and “vol”. Percentage works as you might expect, but vol is a little different. It came about for practical, historical reasons. As Prof. Poliakoff comments in this video, hydrogen peroxide is prone to going “flat” – leave it in the bottle for long enough and it gradually decomposes until what you actually have is a bottle of ordinary water. Particularly in the days before refrigeration (keeping it cold slows down the decomposition) a bottle might be labelled 20%, but actually contain considerably less hydrogen peroxide.
What to do? The answer was quite simple: take, say, 1 ml of hydrogen peroxide, add something which causes it to decompose really, really fast (lots of things will do this: potassium permanganate, potassium iodide, yeast, even liver) and measure the volume of oxygen given off. If your 1 ml of hydrogen peroxide produces 10 ml of oxygen, it’s 10 vol. If it produces 20, it’s 20 vol. And so on. Simple. 3% hydrogen peroxide, for the record, is about 10 vol***. Do not mix up these numbers.
*** Naturally, there are mole calculations to go with this. Of course there are. For A-level Chemists, here’s the maths (everyone else can tune out; I’m adding this little footnote because I found this information strangely hard to find):
Hydrogen peroxide decomposes as shown in this equation:
2H2O2 –> 2H2O + O2
Let’s imagine we decompose 1 ml of hydrogen peroxide and obtain 10 mls of oxygen.
Assuming the oxygen gas occupies 24 dm3 (litres), or 24000 mls, at standard temperature and pressure, 10 mls of oxygen is 10 / 24000 = 0.0004167 moles. But, according to the equation, we need two molecules of hydrogen peroxide to make one molecule of oxygen, so we need to multiply this number by two, giving us 0.0008333 moles.
To get the concentration of the hydrogen peroxide in the more familar (to chemists, anyway) mol dm-3, just divide that number of moles by the volume of hydrogen peroxide. In other words:
0.0008333 mols / 0.001 dm3 = 0.833 mol dm-3
If you really want to convert this into a percentage by mass (you can see why people stick with “vol” now, right?), then:
0.833 mol (in the litre of water) x 34 g mol-1 (the molecular mass of H2O2)
= 28.32 g (in 1000 g of water)
Finally, (28.32 / 1000) x 100 = 2.8% or, rounding up, 3%
In summary (phew):
10 vol hydrogen peroxide = 0.83 mol dm-3 = 3%
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