Combining skincare ingredients the right way – #AskDoctorAnne

There are a few questions I get again and again in the comments on my videos, so instead of answering them only individually, I figured I would use them for a new series – #AskDoctorAnne.

Which sounds pretty catchy if I dare say so myself.


Combining skin care ingredients the right way
Any questions? Ask the doctor!


And the first topic I wanted to address is: Combining skincare ingredients.

Are there ones that you should never combine? Some that actually enhance each other? Does that depend on strength, concentration or time of the day?


It is actually a bunch of questions rather than one, which is why this is going to be a three part series:

  1. Combining skincare ingredients the right way (what you are reading today)
  2. Combining Retinol with other ingredients like Vitamin C, AHA or BHA (coming next week)
  3. Combining Vitamin C with other ingredients like Niacinamide or Acids (coming in two weeks)



What are active ingredients?

To better understand this article, please note that I will follow the concept of dividing ingredients in so called “active ingredients” and “other ingredients”. I struggle a little with this concept, to be completely honest, as everything we put on our skin serves a purpose, not only the so called actives.

Just because something is more aggressive, for example an AHA over a humectant, that doesn’t mean that the humectant has less effect on the skin.

It makes it easier to talk about though, as the basic beneficial ingredients like humectants, emollients and occlusives usually are less reactive, so they can easily be mixed.


What is a serum? Doctor explains
Do you really need all these?


Why combine skincare ingredients in the first place?

Probably the most important question of all.

In recent years the trend has been “more is always better” in skincare routines, be it 10 step Korean Beauty or just excessive serum layering. At the same time, skincare actives have become easier to get access to, with brands like The Ordinary and The Inkey List offering quality formulas at drugstore prices. Which is, don’t get me wrong, a great thing.

Great skincare for everyone, I am here for that! But, and that is a big but, more is actually NOT more when it comes to skincare.

I know it doesn’t look as if I practice what I preach because I test so many new products, but my everyday routine is fairly simple, and with everything I have learned it has become even more streamlined.

Because of that, and that is the key message right here at the beginning, I don’t think you need to combine that many “actives” anyway. For 95% of people out there, a basic cleanser, moisturizer, SPF routine, paired with two, maybe three actives will be enough.

And if you take into account that you have morning and night to use these actives, there should actually be no need to mix them.

As I know though that most of you will not listen to this advice, let’s get into the nitty gritty of mixing your skincare ingredients like a pro!


The basic rule of combining skincare ingredients

If you can get it over the counter, you can mix it. Simple as that.

And by mix it, just to be clear, I mean apply the products to the skin as part of the same routine. not mixing them in the palm of your hand. You can of course also mix products in the palm of your hand, but depending on the textures that could be problematic, as some don’t mix well. Once a product is on, it will start reacting with your skin immediately, so the chances of interrupting that with what you put on top are minimal. If you want to be on the safe side, wait for the product to dry down completely. Once that has happened, the only thing you can do to stop its efficacy is rinsing or scrubbing it off.

Should you plan on combining two actives, I think it is always best to apply one first and then the other rather than making your own concoction, for formulating reasons. Skincare products are formulated a certain way for a reason, if you start messing with it, it can alter the product and reduce its greatness.

Think cooking – I love stew and I love ice cream, both are amazing on their own. Mixing them would ruin both though. Not in a way that they get dangerous, but just by becoming a disgusting, unpleasant mixture. Have the stew and then the ice cream – much better!


Everything you need to know about Vitamin C
So Vitamin C… What about the pH sensitive ingredients?


What about the pH when mixing skincare ingredients?

Some ingredients work better at a certain pH than they do otherwise, with Ascorbic Acid being the best example (read more about Vitamin C here). If you alter the pH of the Ascorbic Acid Solution, you will make it less efficient, which is why adding it into other skincare products probably isn’t the best idea. One more reason not to mix your products in the palm of your hand before you apply them to the face!

How about the skins pH though?

If I apply something acidic like a Vitamin C Solution and then a Retinoid, which prefers a pH of 5,5, wouldn’t it be better to wait for the skin to get back to it’s normal pH before? This is where the “20 minutes between layers” rule comes from, but, I hate to break it to you, the skins pH takes longer than 20 minutes to get back to normal. It is more around the two hours + mark, so unless you are willing to wait 2 hours between layers, you can either ignore it or not combine ingredients that need a different pH.

I personally prefer the “ignore” route, as I think the biggest change to our skins pH comes from washing it (the water makes it more alkaline), but a few drops of acidic serum or a few pats of an acid toner won’t make that much of a difference there.

Is it possible that it reduces the effects on your skin by a few percent? Yes.

But is that likely to play a role in the long run? I don’t think so when it comes to over the counter skincare.


Are there ingredients you can mix with everything?

I hope I made it clear above that in my opinion you can mix all the over the counter ingredients available to your hearts desire, but if you want to be on the safe side, here are a few that play nicely with everything: Hyaluronic Acid in its various forms, other humectants like Glycerine, Silicones and Niacinamide.

Which means that your basic cleanser and basic moisturizer can really be combined with all the active layers you want to sandwich in between.


Any exceptions to the rule?

Of course!

I am strictly talking over the counter products here. Anything that would need a prescription like Tretinoin, and, at least in Germany, Hydroquinone and Benzoyl peroxide in higher concentrations, should be approached with caution and should be used in your routine as advised by the person prescribing it to you!

Tretinoin because it is very potent and can have severe side effects like skin irritation and peeling when paired with acids, Hydroquinone because it has again some severe side effects if used incorrectly and Benzoyl peroxide because it is very reactive (and drying) and could render ingredients mixed into it like Vitamin C actually useless.


Woman scratching her face
Ever felt like you want to scratch off your skin?



Just because you CAN mix something though doesn’t mean you should. Depending on the ingredients you choose, mixing them can increase your risk of irritation. Not because the ingredients react with each other, but because they react with your skin in a similar way, maximizing the effect and side effects.

Maximized effects are NOT always a good thing in skincare. In fact, more often than not they aren’t. Overexfoliation, chronic inflammation, redness and breakouts are not uncommon in skin that is exposed to too many maximized products, and I strongly encourage you to be gentle with your skin above everything else (read more about a damaged skin barrier here).

Chronic inflammation does contribute massively to prematurely aging the skin, something we all are trying to avoid – no point in spending a ton of money on skincare, only to stress your skin by applying all of them.


Bottom line

You can combine all ingredients that you can get over the counter, but neither do you need to, nor should you.

The reason for that is not safety issues or reducing the efficiency of your skincare, but the fact that you need less actives than you might think and that too much of a good thing is often bad in the long run.


How to mix your skin care ingredients the right way! The basic rules, the dos and don´ts and the important role of texture and pH.
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And for all your specific questions regarding Retinol and Vitamin C, make sure to come back next week.

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