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Does the science behind shampoo stack up?

Shampoo science

Are you bamboozled by the proliferation of shampoo claims? Can it really thicken hair fibres from within? And should you be relieved or suspicious when your shampoo tells you all the things it doesn’t contain, such as parabens, silicones and fragrances?

As children, my parents washed their hair with soap. And when I was a child, we chose our shampoo for dry, normal or greasy hair, and anti-dandruff shampoo was simply revolutionary. Now the choices are endless – you can even buy shampoo that claims to make your hair look ten years younger!

So we examined the science behind the shampoo claims using an expert panel made up of a dermatologist, trichologist (hair and scalp specialist), chemist and marketing experts.

Shampoo claims

The experts explained what shampoo ingredients do, and which ones (those containing botanicals such as the plant extract red algae, vitamins and amino acids) are more likely to give a feel-good factor, rather than deliver tangible benefits in the small amounts likely to be present.

They also clarified that free-from claims are not quite as simple as they seem. While some shampoos, such as Herbal Essences Clearly Naked shampoo, are free from ingredients such as parabens (a preservative), this is not infrequently replaced by the preservatives methylisothiazolinone and methylchloroisothiazolinone. This combination is a known skin sensitiser or allergenic.

So what we found was that while shampoos can legitimately make all the claims they do, it’s not nearly easy enough to see the manufacturers’ evidence backing up their substantial claims, with many declaring it ‘commercially sensitive’.

Clearer claims

I don’t think it wouldn’t be far-fetched to expect all companies to clearly let us know exactly what we’re paying for and how it works, as L’Oreal did. And especially so when we’re paying premium prices.

So do you think that these claims need clearing up? Or do we just accept that this is the way marketing works, take some claims with a large dose of salt (sodium chloride thickens your shampoo after all), and enjoy the choice and the feel-good factor?


All these marketing claims are wasted on me. I look at the unit price for shampoo. If the product smells unpleasant or there is some other problem I will avoid it in future. I want shampoo that I can use daily without damaging my hair or scalp, and so far I have had no problems. If I did, I would study the ingredients list carefully and compile a list of products to avoid.

Perhaps we need to make the public aware that their hair (the part that is visible) is not alive, so that vitamins etc. are going to achieve nothing.

Thanks Joanna for this Convo. Shampoos must be a contender for the most ridiculous marketing in the UK.


This, perhaps, highlights that any claims made for any product should be substantiated. If not the claims should be withdrawn. That surely is a job for the EU regulators.

As far as marketing is concerned, it has been going on for thousands of years. A supplier will tell you all the positive features of a product, but is unlikely to advertise the negative ones. If we don’t know by now to take advertising claims with a pinch of sodium chloride and use our own judgement and instincts (helped, perhaps, by exposures from Which?), we never will.


Claims that cannot be substantiated should never have been made in the first place. That’s why all new claims should be vetted before they are made in the first place.


As has been said elsewhere there are far too many companies to monitor for every claim made, unless you want to establish a huge bureaucracy (and we already have enough bureaucrats). The penalties for making unsubstantiated claims should deter people from making them in the first place. For example publishing similar adverts retracting the claim and admitting telling untruths, withdrawing all products covered by the advert from retailers . Fines can be built in as an operating cost. Penalties should be designed to stop people before they act deceitfully.


I said that every NEW claim should be substantiated. The sooner we start the better.

The vetting is a job for scientists, not bureaucrats, and the work should be funded by the companies that want to make a new claim.

If you wait until complaints are lodged with the ASA, the company will have the opportunity to make money from selling dodgy products until successful action has been taken.


There will be an awful lot of NEW claims. I’d rather qualified scientists were put to better use than vetting claims. And it is not just “scientific” claims – try financial products, travel, medicine. We need doctors, not claims checkers.

I made the point that penalties imposed should be such as to make it not worthwhile for a company to make untrue claims. i want to stop it before it happens, not waste time putting it right afterwards.

I would hazard a guess that VW will think very hard, for example, about making false claims in the future, given the huge financial and reputational damage done to their company. I am sure shareholders would agree.

But we do need to grasp the nettle. Banks are a prime example of where we have not put the kind of penalties on place to act as a real deterrent. How difficult has it been afterwards to unravel their own dodgy practices? Perhaps imprisonment for gross offences for those who perpetrate, and knowingly support, very serious breaches.


I don’t see why there should be numerous NEW claims. At present there is a limited number of claims that can be made for the health benefits of foods, for example. All manufacturers can share these claims.

I suggest that we run our country for the benefit of its citizens and not product manufacturers.


There are far more products involved than that, coming to us from worldwide. I would prefer to see trained and skilled people used productively, to help the “citizens” and the economy, not in another layer of bureacracy. Tackle campylobacter in the food industry, help the NHS, design and create manufactured products, teach out young people properly, is far more important. Deterrent penalties would prevent such a huge waste of resources.