Which Skincare Ingredients Shouldn't You Mix In Your Products?


With the innovations in skincare ingredients in recent years, many more potent ingredients that were previously only used on a trip to a board-certified dermatologist are now being used in our homes. This means that a lot of us are using ingredients we perhaps don't understand that well, leading to mixes that should never happen.

When it comes to ingredients you should never mix, there is quite a list that you should be aware of. Many common skin care ingredients cannot be mixed because they can cause irritation and other negative side effects, or they simply cancel each other out.

In this article, we're going to take a look at some of the most common active ingredients in skincare and explore what they do, what they can be mixed with, and what they should never be mixed with.

Take a look now to find out more about mixing skincare ingredients.

Which Skincare Ingredients Shouldn't You Mix In Your Products?

Why Shouldn't I Mix Skincare Ingredients? Skin Irritation, Discolouration, Etc.

So, why can't you mix some ingredients?

It probably seems incongruous to not be able to mix skincare ingredients because they're all good for your skin, right? Well, mixing some ingredients can actually lead to the opposite of good.

Mixing ingredients that shouldn't be mixed can lead to skin irritation, dryness, and other potentially irritating side effects. In addition, you may also counteract the good of one ingredient, meaning you've wasted the ingredient.

A skincare routine should be built with your skin's health in mind, and so knowing which skincare products and ingredients shouldn't be mixed can help you to create the perfect products for a healthy skincare routine.

Common Skincare Ingredients

There are some common ingredients in skincare products that shouldn't be mixed and others that can be mixed for even better results. Below, we've taken a look at these ingredients and summarised what they do, what they can be mixed with, and what they should never be mixed with.


Retinol is an incredibly popular ingredient in skincare these days. Previously only available on prescription or via a board-certified dermatologist, this ingredient can be used in a variety of ways.

What Is Retinol?

So, what is retinol?

Retinol is primarily used for those with mature skin and as a treatment for acne-prone skin. It is a derivative of vitamin A and is the over-the-counter version of retinoids, though they are not actually the same product.

Retinol can be used to reduce the look of wrinkles and fine lines. Unlike many, many skin products, retinol is not used to remove dead skin cells, instead, it penetrates the pores deeply and protects the skin from free radicals.

It helps to boost collagen production and the elasticity of the skin, helping to keep the skin plump and young. It can also be used for severe acne, improves skin texture and boosts skin cell turnover.

What Can I Mix Retinol With?

Retinol is an ingredient that must always be used with caution. There are a lot of ingredients you should never mix retinol with but it can be mixed with SPF treatments for sun protection and moisturising agents.

Retinol can make you more sensitive to the sun, meaning SPF is a must if you're using this ingredient. SPF is a must in all skincare though, so this shouldn't be too difficult.

You should also ensure you moisturise after using retinol using a product like hyaluronic acid, which can help the skin to draw in and hold moisture.

What Shouldn't I Mix Retinol With?

Retinol shouldn't be used alongside AHAs or BHAs, like salicylic acid and malic acid. Both these ingredients are exfoliating and, used on top of retinol, could lead to dryness and irritation.

Retinol is also not compatible with benzoyl peroxide, another acne treatment. These two ingredients cancel each other out so it is useless to combine them.

Finally, retinol should not be combined with vitamin C. These ingredients are best used at opposite ends of the day i.e. morning routine and evening routine.

Which Skincare Ingredients Shouldn't You Mix In Your Products?

Vitamin C

Topical vitamin C is a hero ingredient in skincare. It has been used widely for a number of years now and many people incorporate it into their skincare routines due to its many benefits.

What Is Vitamin C?

Vitamin C is an antioxidant that helps to protect the skin from environmental factors, like the sun, oxidative stress, and free radical damage.

It is thought to slow the process of aging, reduce the look of wrinkles and fines lines, as well as prevent sun damage, brighten the skin, lighten dark spots, and help to treat acne.

What Can I Mix Vitamin C With?

Vitamin C is a good ingredient to combine with other antioxidants, such as vitamin E. Combining vitamin C with other antioxidants can help to boost the positive benefits of vitamin C.

You should also always layer vitamin C underneath sunscreen. This is because they complement each other and help to protect the skin from sun damage.

What Shouldn't I Mix Vitamin C With?

As mentioned above, vitamin C should not be combined with retinol. Vitamin C is much more effective in the morning whereas retinol is best for nighttime skin products.

Alpha-Hydroxy Acids and Beta-Hydroxy Acids (Glycolic Acid, Salicylic Acid, Etc.)

When it comes to products that exfoliate, the world has mostly moved on from physical exfoliators and it's all about the chemical ingredients. Cue: AHAs and BHAs.

What Are AHAs and BHAs?

Alpha-hydroxy acids (glycolic acid) are generally derived from sugary fruits and are used to peel away the top layer of skin. This helps giveaway to a newer, more evenly pigmented layer of skin and helps to keep skin smooth and soft.

AHAs are used for dark spots, uneven skin tone, enlarged pores, fine lines and wrinkles, and to improve skin texture. They are generally safe for all skin types, but those with sensitive skin should gradually build up use.

Beta-hydroxy acids (salicylic acid) are oil-soluble and penetrate deeply into the pores to remove dead skin cells and remove excess sebum. They're generally used for acne treatments and sun damage.

What Can I Mix AHAs and BHAs With?

AHAs and BHAs should always be followed up with moisturising treatments and sun protection. Ingredients like ceramides to protect the skin barrier, hyaluronic acid to draw in moisture, and glycerin to hydrate and soothe skin are all good exfoliation follow-ups.

What Shouldn't I Mix AHAs and BHAs With?

As previously mentioned, combining AHAs and BHAs with retinol can lead to skin sensitivity, irritation, and redness. It is suggested that AHAs/BHAs should be used on different days to retinol to protect your skin.

Which Skincare Ingredients Shouldn't You Mix In Your Products?


A versatile and highly tolerated ingredient, niacinamide is a popular ingredient in skincare and can be found on its own and combined with other ingredients.

What Is Niacinamide?

A combination of vitamin B3 and nicotinamide, this ingredient has antioxidant and anti-inflammatory properties. It is mostly used to treat uneven skin tone and is a staple in many a skincare routine.

What Can I Mix Niacinamide With?

Niacinamide is a pretty well-tolerated ingredient, meaning it is a good choice for mixing skincare ingredients. It works with most other ingredients, including the usually-irritating retinol and benzoyl peroxide.

What Shouldn't I Mix Niacinamide With?

The one mix you shouldn't make is niacinamide and vitamin C. Both ingredients are antioxidants and commonly found in skincare, but using them too closely can diminish the good both ingredients do.

Benzoyl Peroxide

Benzoyl peroxide is an ingredient generally available in pharmacies and has long been used to treat acne.

What Is Benzoyl Peroxide?

Benzoyl peroxide is a great ingredient for acne treatment, though it can be incredibly drying and should be used with caution. It works by reducing the amount of acne-causing bacteria on the skin's surface and generally comes in gel or wash format.

A board-certified dermatologist may suggest using this treatment and it is generally safe if used correctly.

What Can I Mix Benzoyl Peroxide With?

Because of the way that benzoyl peroxide can dry out your skin, this ingredient works best alongside moisturising agents. It should be layered on before moisturisers and combined with ingredients that help the skin to draw in and lock in moisturiser.

What Shouldn't I Mix Benzoyl Peroxide With?

As we mentioned above, retinol and benzoyl peroxide cancel each other out and so it is useless to use them together. Use one or the other and find which works best for you.

You should also be cautious of using benzoyl peroxide with a commonly prescribed acne treatment called tretinoin as benzoyl peroxide may deactivate it.

Conclusion: Which Skincare Ingredients Not To Mix

There are many interactions between common ingredients in skincare that need to be considered when creating products for targeted skincare. Choosing the right ingredients means creating the best and most effective product.

When considering interactions, consider which product a consumer would layer on afterwards to help them build a safe and effective skincare routine.

For more information on custom skincare formulas, check out our custom formulations page.