Serum vs ampoule vs essence: what’s the difference and what do you actually need

ROUTINE

Serum, ampoule, booster or essence: what’s the difference?

The difference between an ampoule, a booster, an essence and a serum lies in the format and the intended use, not in any binding strength. A serum is a light, usually watery or gel-like skincare product containing active ingredients, applied after cleansing and before your cream. An ampoule is essentially the same thing, just filled into small, often individually sealed portions and intended for a limited period. Hydrating ampoules for the face are therefore usually nothing more than hydrating serums in course format. A booster is a small bottle containing one or a few active ingredients that you mix into your cream or serum. An essence is best known from Korean and Japanese skincare and sits somewhere between water and serum in consistency. And ‘concentrate’ is a catch-all word for anything that is meant to sound like more. The categories overlap considerably: a concentrate can contain less active ingredient than an ordinary serum, and an essence can do more than an ampoule. The table shows how the terms are most commonly used by retailers.

Are these terms regulated or just marketing?

The terms are not regulated: no rule specifies how much active ingredient an ampoule, a booster or a serum has to contain. They are marketing categories that describe a type of packaging and an idea of how to use it. The rules the EU has laid down for cosmetic claims come in at a different point. Under Regulation No 655/2013, if a product is advertised with an ingredient, that ingredient must be deliberately present. Anyone who attributes an ingredient’s properties to the finished product needs evidence to back that up – the regulation cites proof that the substance is present at an effective concentration as one example. What gets scrutinised, then, is the claim about the active ingredient, not the word on the box. Whether a manufacturer calls its product an ampoule, an elixir or a concentrate tells you nothing about that.

The sheer number of names is mainly down to the logic of product ranges. Every new category is a new step, and every step is another product in your bathroom cabinet. This is particularly visible in Korean routines, where essence, ampoule and serum are applied one after the other. The guide to Korean skincare and what the 10-step routine does and doesn’t do takes a closer look at which of those steps actually pull their weight.

What is an ampoule treatment, and does it do more than a serum?

An ampoule treatment does not automatically do more than a serum, because at its core it is simply a serum used in single portions over a limited period. Its real advantage lies in the packaging. Some active ingredients are sensitive to air and light, the best-known example being pure vitamin C. A review in the Journal of Cosmetic Dermatology describes how the instability of this water-soluble vitamin and the difficulty of getting it into the skin pose problems for formulators. A freshly opened, airtight single dose is one answer to that. Another is a more stable form of vitamin C that works in an ordinary serum.

The catch is the timescale. Studies on active ingredients measure their effects over weeks and months, not over a single week. In a study in Dermatologic Surgery, 50 women applied 5% niacinamide to one half of the face twice a day for 12 weeks, with measurements taken at four-week intervals. What a course of a few days can noticeably deliver is moisture: your skin feels smoother and looks plumper. Once you stop, the effect fades again. A course is therefore no substitute for skincare you use consistently.

What is a booster for?

A booster is meant to add a single active ingredient to your existing skincare, for example a few drops of niacinamide or vitamin C stirred into your cream. That sounds flexible, but it has two weak points. First, you do not know the final concentration. How much active ingredient reaches your skin depends on how many drops you mix into how much cream. Second, you change the formulation. A review in the International Journal of Cosmetic Science shows that the type of emulsion, the emulsifier and the emollient oils can influence how well an active ingredient gets into the skin. Mix two products and you create a third one that neither manufacturer has tested in that form.

A booster makes sense if your cream suits you well and you are missing just one particular active ingredient. If you are missing several, a serum that contains them together from the outset is usually the simpler solution. The underlying question is how many products your skin really needs, and the answer is rarely ‘just one more’.

Do you need an essence if you already use a serum?

If you already use a serum, in most cases you do not need an essence. An essence mainly delivers humectants in a very thin layer. If your serum already contains glycerin, hyaluronic acid or similar humectants and is followed by a cream, that combination already does the job. The essence then mainly adds texture and one more ritual, but no new function. The article on whether you really need both serum and cream explains whether the two are enough for you on their own.

There is one exception: if your serum consists almost entirely of a single active ingredient and contains hardly any humectants, an essence can fill that gap. Often, though, a different serum is a better choice than an extra product. And if you do apply several layers, the rule is thinnest to thickest. Exactly where each step belongs is explained in the overview of which skincare step goes where in the morning and evening.

How can you tell whether a product really contains more active ingredient?

The only way to tell whether a product really contains more active ingredient is from disclosed percentages and the ingredient list, not from the product name. Five checks will help you:

1. Percentage per active ingredient: ‘5% niacinamide’ is a verifiable claim, ‘highly concentrated’ is not.
2. Position in the ingredient list: under the EU Cosmetics Regulation, ingredients are listed in descending order of weight. Substances below 1 per cent may follow in any order. If an active ingredient appears far down the list, it is usually present only in a small amount – exactly how much, the list does not reveal.
3. Comparison with studies: is the stated concentration within the range used in research?
4. Stable form and suitable packaging: sensitive active ingredients need a stable variant or packaging that keeps out air and light.
5. Price per application rather than per pack: small bottles look cheap but often cost considerably more per millilitre.

One example of a serum with several active ingredients is The Essential, the serum in the Duo. It combines niacinamide, vitamin C in the stable form 3-O-Ethyl Ascorbic Acid, and zinc PCA. For The Duo of serum and cream as a whole, the concentrations are disclosed: 5% niacinamide, 2% vitamin C as 3-O-Ethyl Ascorbic Acid and 1% zinc PCA in total. That is not a promise of results, but it is a figure you can compare with studies like the one mentioned above. In her review on Judge.me, Andrea G. writes about the two products: ‘Just two products that bring together everything you need’ (review translated from German). How to judge a serum against criteria like these is shown in the guide on how to recognise the best serum for mature skin.

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