Can your hair dye kill you?

Hair dye reaction

Anyone can develop an allergy to anything anytime.  Allergic reactions vary in severity, but in rare cases some can kill you.  So when you make it to your bed tonight you can thank providence for sparing you for one more day.

But lets get things in perspective.  Although in theory anything can be an allergen in practice if you want a successful career as an  allergen you really need to be able to get into the bloodstream reasonably easily.  The immune system also has to interpret it as a problem.  So very common things, like sugar for example are not going to provoke allergies.  Nor are things that just don’t react very much. So you can use things like silicone in breast implants with few problems.

To provoke an allergic reaction the immune system needs to have contact with the allergen first, so it can recognise it and produce a reaction to it.  This means that the soonest you can develop an allergic reaction is the second time you come into contact with it.  More often you’ll need to have had a fair bit of exposure first. 

Allergies are a fact of life and are on the rise.  The reason for the increase isn’t immediately obvious, but I think a biochemist I heard on the radio isn’t far off.   She says that basically the way we live now doesn’t leave much for the immune system to do.  So when it does find something to react to, it does it in a big way.  The most extreme of reactions is anaphylaxis.  The so called anaphylactic shock is so severe that it can be life threatening or even fatal.  Luckily this kind of reaction is extremely rare, leading to only about 20 deaths a year in the UK, but even so it is a sobering thought that there might be no particular indicator that someone is prone to one until they have one.

As a rule cosmetic products don’t cause this kind of problem because they don’t contain much that will get through the skin into the bloodstream, and because very few cosmetic ingredients have much potential to provoke allergic reactions.  But if you were going to pick on the products that have the strongest chance, hair dyes are the ones that are most likely to be an issue.  For a start, the colourants have to get into the hair to have an effect, and this means that they are likely to get across the skin and into the blood stream if they get the chance as well.  On top of that they tend to be used with things like ammonia which are likely to irritate the skin and make it more permeable.  (These are the culprits if your scalp feels dry and itchy after you have dyed your hair).

Most of the colourants used are at least potentially likely to provoke an allergic reaction.  One in particular, p-Phenylenediamine, has been shown to cause allergies in quite a large proportion of people.  (It is often abbreviated to PPD.)  I haven’t been able to find any figures for the population as a whole, but a recent study in Thailand found just under 7% of people with eczema reacted to it.  People with eczema are way more likely than anyone else to be sensitive to chemicals in general because they have both weaker skin barriers and very active immune responses.  So if only 7% of them react to it the number of reactions in the population as a whole is going to be pretty low.   On top of that the amount getting into the blood stream during the hair dying process is not going to be very high.  Applied with care the likelihood is it will be close to zero. So the risks of getting any kind of reaction at all is pretty slim.

But even so, lots of  hair dyes get sold and even a very low level of reaction means that there are a great many  reactions to them reported.   Of course a skin reaction is a long way from being a fatality.  Millions of hair dyes are sold every year, so this is just as well.  There are only about 20 deaths every year from anaphylaxis.  How many of those deaths can be attributed to the use of hair dyes?  The answer is nobody knows, but the probability is that it is none of them.  Drug reactions, foods like peanuts and bee stings are all listed as major causes of anaphylactic shock.  Neither of the cases in the news at the moment have definitively been linked to any chemical in hair dye, let alone the specifically the p-Phenylenediamine which is being discussed in some of the press coverage.

So on the whole, I don’t think there is a great risk of suffering any ill effect from using a hair dye.  I don’t use them myself as a matter of course, but as it happens I am just starting on a project where I will be using exactly the p-Phenylenediamine that some journalists are raising concerns about.  Having looked into it, I am quite happy to carry on and don’t feel in the slightest danger.  But I have to concede that there is a risk, albeit in the hundred millions to one against.  If however you don’t want to take any risk at all there is one and only one course of action open to you.  That is to stop dying your hair all together.  Simply avoiding hair dyes that contain p-Phenylenediamine is not enough.  The way the immune system works, you cannot be sure that you won’t get the same reaction from closely related chemical species.  So the other components of hair dye are quite likely to have the same effect.   Switching to natural alternatives won’t help.  These have pretty much the same problem.  The lawsone found in henna has enough similarities to p-Phenylenediamine that there is still a risk that it would provoke the same reaction.

Your attitude to risk is a personal matter and none of us are very good at being entirely logical about it. We all know about the risks of illicit drugs, casual sex, smoking and alcohol, or even driving our cars too fast, but we all do at least some of these things (though probably not all at the same time).  On the whole, the chances of coming to any harm from a hair dye, which is microscopic compared to risks we routinely take every day seems to me to be not worth worrying about.  You may disagree, and you are perfectly entitled to do so.  But please don’t get suckered into buying special ‘safe’ brands that avoid particular ingredients.   PPD Free brands  for example won’t be any safer.


I was surprised to see an article in the Guardian – the home of statistics superhero Ben Goldacre – pushing this story.  It has to be said that the author is rather cavalier with her own health.  She seems to have had an anaphylactic episode, which according to this account was life threatening, but has not followed this experience up with a patch test to positively identify the causative agent or agents.  The whole tone of the article is a bit alarming.  This is only achieved by glossing over the fact that there is no proven link between p-Phenylenediamine and either of the two cases quoted.

This is the paper that assessed the degree of reactions to some common allergens among eczema patients.  It was done in Thailand where the pattern of exposure to hair dye ingredients might be very different to that in other countries, but nonetheless it gives an idea.

J Med Assoc Thai. 2010 Dec;93 Suppl 7:S7-14. Contact allergy in eczema patients in Thammasat University Hospital. Disphanurat W.

10 thoughts on “Can your hair dye kill you?”

  1. This is very interesting.. I hold my breath a bit every time I dye my hair.. but I am not sure how you are supposed to patch test all the ingredients when the instructions say you have to apply immediately once the two tube contents are put together.. do they expect you to buy two.. one for a patch and one to use? And to patch every time? expensive. So, I really think that hair dye brands should do a tiny patch amount within each packet of dye.. people would be much more likely to patch that way x

  2. Great post! Interesting what you say about henna too. Henna sites often warn about the danges of ppd, but I’ve recently had ‘safe’ hair dye’s suggesting I was at danger of developing a reaction to my henna. Like BBB i’ve always wondered about how you are supposed to patch test with packet dyes, much easier with henna…not that I do….

  3. Thanks for the comments. With regards to patch testing, here are some figures you might want to ponder. The CTPA quote less than 1.5% as the figure for the number of people who get reactions to hair dyes in general. I don’t know where that figure comes from and it sounds extraordinarily high to me. I have asked a hairdresser I know who has been dying hair for 12 years and she has never had a single reaction reported back to her – but maybe she is either very lucky or very careful.

    If you are in the complaints department of a company selling millions of units you are going to be getting sack loads of mail if your product has that level of issues. If I were in that position I would do two things. First I’d get some pretty intensive counselling and probably some drugs to cope with all the negativity. Second I would plaster my packs with warnings about allergic reactions and urge people to do tests to make sure they aren’t going to have a problem.

    But from the consumers point of view, your chances are pretty near to 100 to 1 against ever having a problem. Doing a test when you change to a new formulation might be prudent and testing before every treatment is cautious which may suit your temperament. But personally I think the odds are good enough that I would give the testing a skip, and indeed have done so even though it would be easy for me. I am lucky enough to suffer from very little in the way of allergic reactions and I would probably think differently if I were more sensitive.

    I hope that is helpful.

  4. I know a friend of mine does the test by mixing just a small amount of the stuff from both tubes in a separate bowl, and applying it behind her ear with a stick. She closes the tubes carefully, and so far hasn’t had any problems?

    1. Your friend’s procedure sounds very sensible. It is only a very small proportion of people who have problems with hair dyes. Millions of them dye their hair regularly for years on end without any trouble. When you read a story in the press it is natural to feel anxious, but it is important to keep things in perspective.

  5. Hi Colin, Curious to know how does phenylketonuria fit into all this? I know there are even diet guidelines for those who suffer from it?

    Also you say “…the amount getting into the blood stream during the hair dying process is not going to be very high. Applied with care the likelihood is it will be close to zero. So the risks of getting any kind of reaction at all is pretty slim”

    Surely, as we have a huge amount of blood vessels in the skin around our head (as we all know from seeing head injuries) something potentially toxic would easily seep through the scalp into the blood? Not sure I agree with you re. your comment above 😉


  6. Hello,
    Interesting reading. I am just back from the hospital after being rushed there in an ambulance after I had an anaphylactic reaction to a dark brown red hair dye. Within minutes of putting it on I had breathing problems, tingling lips and head, shaking. I almost died today. The final doctor I spoke with advised never to use hair dye again as they are cocktails of chemicals which can and do cause reactions in some people, albeit in small amounts. So whatever the chemical or combination is in hair dyes they are responsbile for some anaphylactic reactions.


  7. There is minimal risk of reactions to hair dye but one point to remember is.. the darker the hair color the more dye will be in it. As in.. if you color with blonde there isn’t much dye used but if you color with black that has the greatest amount of dye used in the color so it will be much more concentrated with dye. The darker you go.. the more dye in the color. If there are any reactions to dye it would most likely be to darker or black colors.. most likely building over time or skin reactions. Maybe rarely a serious reaction.

  8. I think what Hairstylist who commented above means is PPD, not ‘dye’. There is a higher ratio of PPD or alternatively PTDS in darker shades of hair dye.

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