Patch testing a new product is something that I stress a lot throughout my articles and reviews.

I consider it the most important step to safely introduce a skincare item into your routine.

In this article, I’ll walk you through everything you need to know about patch testing and I’ll focus specifically on one of the most popular brands – The Ordinary. I’ll cover the following:

  • What is a patch test;
  • How to properly patch test a new product;
  • What to expect when patch testing The Ordinary’s skincare;
  • What does The Ordinary patch testing guide say;
  • How to properly patch test The Ordinary’s products.

Let’s get started.

A patch test is a method used to find out whether certain substances will cause skin irritation or allergic reactions to your skin. It’s a prevention method used to show you whether your skin can tolerate a particular skincare product, and thus, if you can safely go on using it in your routines.

If you have a complicated skin routine or you’ve started using several products at the same time, performing a step-by-step patch test of each product can show you which item can trigger a negative reaction.

This method involves applying a small amount of the product onto your skin and leaving it on to see if a reaction develops. Common culprits for skin reactions include alcohol, essential oils, perfume, strong acids, and others.

Unlike skin prick tests, patch testing takes longer to show results – sometimes a few days. However, it’s a great way to figure out your skin’s reaction to certain products without risking experiencing severe side effects.

You can schedule a patch test with a dermatologist or doctor, but best of all – you can also perform a patch test at home. That way, you can try a new product before fully incorporating it into your routine (something I recommend always doing).

How to properly patch test

The Ordinary Patch Test

Although there are many different ways to approach a patch test, I advise taking the following steps. Below you’ll find a general guide to patch testing, whereas later on in this article, I offer specific information on patch testing different TO products.

To get started, choose an area of your skin where the product is unlikely to be accidentally washed or rubbed off. For example, the inside of the arm or the bend of the elbow are great options. Apply a quarter-sized amount of the product to the chosen patch of skin, making sure that it is applied as thickly as it would be during regular use.

Next, leave the product on the patch of skin for the same amount of time you would normally leave it on – according to your skin goals, or the instructions of the product.

If the product is typically washed off (say you’re using a cleanser), leave the product on for at least 5 minutes, or follow the specific instructions provided by the manufacturer.

Repeat the patch test twice a day for 7-10 days, as it may take some time for a reaction to occur. If the skin reacts strongly to the product, wash it off immediately and stop using it. A cool compress or petroleum jelly can help you alleviate any discomfort experienced at that time.

But why is it important to patch-test products for a longer period?

Let me introduce you to a condition called “contact dermatitis”.

Contact dermatitis is a type of delayed hypersensitivity reaction that can take several days to show up. There are two types – irritant contact dermatitis (ICD) and allergic contact dermatitis (ACD).

ICD, or irritant contact dermatitis, occurs when external substances damage the skin’s epidermal cells, leading to an inflammatory response. On the other hand, when an individual comes into contact with an allergen through their skin, they may experience ACD, which is an allergic reaction. The body’s immune system mistakenly perceives a harmless substance as a threat, resulting in an immune response that triggers inflammation and irritation.

Although delayed symptoms can be an indicator of an allergic reaction to a new substance, it is also possible for symptoms to develop at any time in the future if a person has been previously exposed to an irritating substance.

So there’s never a guarantee that you won’t experience contact dermatitis but the longer patch testing helps to reveal if you’re prone to it in a much safe and controlled way.

Just imagine you slap on a moisturizer to your face only to find out that you’re turning tomato red the next morning. Patch testing can prevent that from happening.

What to expect when patch testing The Ordinary products

When conducting The Ordinary patch testing, it’s important to know what the potential side effects are.

Several mild, expected reactions are considered normal and most of us will have at least one of them, but there are also more severe cases when you’ll want to stop using a product immediately.

The Ordinary patch test’s mild reactions include dryness, itching, slight burning sensations, and initial redness. All of these are experienced immediately upon application and are expected to dissipate a few minutes after.

Patch testing The Ordinary can also cause moderate to severe side effects, like strong burning sensations, irritation, blistering, swelling, and allergic reactions.

If you experience any of these reactions, it’s highly advisable to contact a dermatologist or doctor and stop using the product that caused the side effects.

Especially if you’ve tried calming down these symptoms but nothing has worked, don’t think twice about seeking professional help.

What does The Ordinary patch testing guide say

One of the most useful things that the brand has compiled is The Ordinary patch testing guide.

The guide is available on the company’s website so if you’re looking for up-to-date and accurate information, you can get all the details you need on new products and how to patch-test them.

However, The Ordinary skincare patch testing guide officially available on their site is rather a general method, similar to what I’ve described at the beginning of this article.

It doesn’t let you know what specific side effects to expect with each product, what’s normal and what’s not, and how to patch-test each individual The Ordinary product most effectively.

I’ll share with you tailored patch-testing methods for some of the most popular products by The Ordinary.

Which are The Ordinary products with the most reported reactions:

The Ordinary Skincare Patch Testing

These are The Ordinary products with the most reported side effects and negative reactions, both mild and severe:

  • The Ordinary AHA 30% + BHA 2% Peeling Solution;
  • The Ordinary Glycolic Acid 7% Solution;
  • The Ordinary Salicylic Acid 2%;
  • The Ordinary Salicylic Masque 2%;
  • The Ordinary Niacinamide 5%, Zinc 1%;
  • The Ordinary powder products – 100% Niacinamide and 100% L-ascorbic acid powder;
  • The Ordinary Vitamin C product range;
  • The Ordinary Retinoids range.

I’ve used these products as a foundation for the insights I offer on The Ordinary skin patch testing.

I’d like to remind you that every user can experience reactions to any skin care product or ingredient, even if you aren’t using The Ordinary’s products.

Remember that reactions can appear even after long-term use.

How to patch test The Ordinary products

Patch testing The Ordinary Niacinamide 10% + Zinc 1%

Patch Testing The Ordinary Niacinamide

There are a lot of discussions about how to patch test The Ordinary niacinamide on Reddit.

Although you may have come across them, here is my recommendation based on tests, experiments, and research:


How to:

The most important thing to remember when patch testing The Ordinary niacinamide serum is to perform the test on dry skin.

Clean a small area of skin on the upper forearm and apply a single drop of product. Avoid washing or rubbing it off.

After 24 hours, rinse the area and keep an eye out for any signs of redness, burning, itching, blistering, or irritation. If any of these symptoms appear at any time during the test, I recommend staying away from the product.


What to expect:

What you can expect from patch testing The Ordinary niacinamide and zinc serum is either no reaction or a very mild one, in the form of itching or slight redness in the area of application.

These are most likely to occur in people who haven’t used a 10% niacinamide serum before.

Over time, the skin is likely to get used to the niacinamide, so my advice is to patch test for 7 days in a row and see how your skin will handle it.

If the reactions are stronger than what I described, I recommend avoiding this product and instead looking for an alternative with a lower concentration of niacinamide, or one that features soothing ingredients in the formula.

A good alternative is the Cos De BAHA Arbutin 5% + Niacinamide 5% serum.


Why can this product be irritating:

The potential irritation from this product mostly stems from the high concentration of niacinamide (in this case – 10%).

Generally speaking, a concentration of niacinamide above 5% is unnecessary.

The higher the niacinamide concentration, the greater the chances of irritation.

All studies that have proven the effectiveness and benefits of niacinamide have been performed using products with concentrations of up to 5%.

A higher percentage of the active ingredient does not always result in better effects. On the contrary – it often correlates with stronger side effects.

I would use a high concentration of niacinamide only if I’m sure my skin can handle it.

Patch testing The Ordinary AHA 30% + BHA 2% Peeling Solution

The Ordinary AHA BHA Peeling Solution Patch Testing

How to:

To do The Ordinary’s peeling solution patch testing, simply apply a small amount of the product onto a dry and clean area of skin on the upper forearm.

The instructions for this peel state that you must leave it on for no more than 10 minutes, so I suggest having an alarm set up for 9 minutes, to allow you some time to wash it off.

Rinse the skin thoroughly.

Observe the zone for any signs of redness, burning, itching, blistering, or irritation within 24 hours of the test.

If any of these symptoms occur, consider this an indicator that the product isn’t your piece of pie.


What to expect:

Common side effects when patch testing The Ordinary’s AHA + BHA product include itching and temporary redness of the skin (for like 10-15 minutes max) after washing.

These are all normal reactions, especially if your skin isn’t used to chemical exfoliants and you’re a newbie in the space.

You can also feel some stinging in areas where your skin is broken – if you have pimples or you’ve picked on your blackheads, for example.

This sensation should also come to pass quickly.

If you experience more intense reactions that are stronger and long-lasting than what I’ve mentioned above, I suggest taking them as a sign that you shouldn’t be using this product and that it’s better to choose an alternative.

A pricey but more gentle option is Paula’s Choice 8% AHA + 2% BHA combo of two leave-on treatments.

It has some calming ingredients to ensure that no reactions will occur and it’s available in travel size too, so it’s easier to test.

However, if you really want to use The Ordinary peel as it’s so dirt cheap, your best option to avoid negative reactions is to try to keep it on the skin for a shorter amount of time than what’s recommended.

This is provided you can still generally handle the serum and have only mild reactions.


Why can this product be irritating:

The main reason for the potential irritation of The Ordinary AHA + BHA peel, in this case, is the high concentration of AHAs (as much as 30%), which is one of the highest you can get in an over-the-counter product.

If you’re someone with sensitive skin, you’ll definitely experience at least itching and redness, and possibly more severe reactions.

Moreover, it’s so common for people to neglect the instructions and keep the product on the face for over 10 minutes.

I honestly don’t understand those who are brave enough to do so – they don’t get increased benefits anyways, so why risk the irritation?

I’ve also seen people applying it on damp skin, contrary to the product’s instructions.

Applying skincare on wet skin is a common tactic for hydrating products, however, it’s extremely risky for any acid-based skincare or for products with powerful actives, in general.

Patch testing The Ordinary Retinol range of products

Patch Test The Ordinary Retinols

The Ordinary offers a range of products containing retinol or retinoids in general.

These serums are ideal for those of us looking to target the signs of aging, fight persisting pimples, or fix uneven skin tone.

Some of the choices you can test include:

  • Granactive Retinoid 2% Emulsion;
  • Granactive Retinoid 2% in Squalane;
  • Granactive Retinoid 5% in Squalane;
  • Retinol 0.2% in Squalane;
  • Retinol 0.5% in Squalane;
  • Retinol 1% in Squalane.

How to:

As a leave-on product, if you want to patch-test The Ordinary’s retinoids, you’ll have to follow these steps. 

Apply a small quantity of the product to clean skin, preferably on the upper forearm. Make sure that the area is dry.

Rinse the zone after 24 hours and observe for any redness, burning, blistering, irritation, or other side effects.

What to expect:

Some of the typical reactions include slight redness during the application, which should be relieved relatively quickly.

It is also possible to experience slight itching.

If you notice reactions that are stronger or last for longer, chances are that your skin cannot tolerate this product.

In this case, I recommend either trying an alternative with a lower concentration of the active ingredient or experimenting with another brand.


Why can these products be irritating:

You’ll probably find it a bit surprising to learn that people often fail to choose the right retinol concentration for their skin.

In general, skincare newbies often assume that a higher percentage of an ingredient means a more effective product.

However, when it comes to retinoids, our skin needs to get used to the ingredient and frequency of use first before we start testing the performance of a new and stronger product.

Overall, you should only use the product once you’ve seen that your skin tolerates it.

There are cases where people have religiously stuck with a product with a 0.2% retinol concentration for years, simply because their skin cannot tolerate a higher percentage – and that’s completely normal and optimal.

I strongly recommend listening to your skin and taking action when you notice symptoms or side effects.

In terms of retinoids, start with the lowest concentration and use the product up to 2 times a week.

Once you start to tolerate it well, you can gradually increase the use to 3 or even 4 times a week.

The moment you realize that you can use the same percentage of retinol every day without seeing any negative skin reaction, you can increase the concentration and choose a product with a higher percentage of retinoid.

If you’re completely new to retinoids, I recommend starting with TO’s Granactive Retinoid 2% Emulsion – it’s the easiest to use and has the fewest initial reactions, yet it’s super effective.

Patch testing The Ordinary salicylic acid products

The Ordinary Patch Testing Salicylic Acid Products

How to:

The Ordinary Salicylic Acid 2%

This is a leave-on product by The Ordinary. Simply follow the steps I’ve outlined above for leave-on products.


How to:

The Ordinary Salicylic Masque 2%

On the other hand, TO’s mask is a wash-off solution. Take the instructions for patch testing TO’s wash-off products and apply them when testing this product.


What to expect:

When patch testing The Ordinary’s salicylic acid products, some of the most common reactions include slight redness shortly after application (especially typical for the mask after washing off), which should pass within a few minutes.

Anything more serious than that means the skin cannot tolerate the product.


Why can these products be irritating:

When using TO’s mask, the irritation mostly stems from the physical rubbing when washing off.

A reaction can be seen as there is kaolin and charcoal powder inside the product, which can be slightly abrasive.

Overall, the concentration of salicylic acid in both products is optimal, meaning that you shouldn’t see any serious reactions, but if you do notice something more concerning, I recommend looking for an alternative brand that offers salicylic acid.

If you find that this option doesn’t work either, you can also try a product with a lower concentration.

I like the La Roche-Posay Effaclar Purifying Foaming Gel Cleanse with 2% salicylic acid as it allows for a short contact therapy (this minimizes any chances of irritation) yet has an optimal concentration of salicylic acid – I use it daily under the shower on my face and body, leave it on for a few minutes and rinse it.

This is enough to keep my pores clog-free and keep acne away.

Patch testing The Ordinary Glycolic Acid 7% Toning Solution

The Ordinary Glycolic Acid Patch Test

How to:

This is another leave-on product that should be patch tested similarly to the rest of this type.


What to expect:

If you’re performing The Ordinary glycolic acid patch test, some of the normal side effects you can experience include slight redness shortly after application, perhaps a slight itching and even stinging, if you have skin breakages such as pimples or if you’ve picked on your skin.

Especially if you have inflamed or red skin patches like open wounds or sensitized areas of skin, a strong stinging is almost guaranteed.

These reactions should pass within a few minutes but if they don’t or if you notice anything more serious than that – take it as a sign that your skin cannot tolerate this product.


Why can these products be irritating:

A concentration of 7% glycolic acid can be too strong for some.

If your skin doesn’t seem to tolerate it, then it might be a good idea to test it with another brand and a lower percentage of glycolic acid such as the Good Molecules 3.5% Glycolic Acid Toner.

Alternatively, you can opt for a gentler AHA by The Ordinary like their Lactic Acid 5% + HA which is very well tolerated by most.


Patch testing The Ordinary 100% powder products

Patch Testing The Ordinary Vitamin C Niacinamide Powders

When speaking of TO’s 100% powder products I’m referring to two solutions in particular – the 100% Niacinamide Powder and the 100% L-Ascorbic Acid Powder.


How to:

Both products are leave-on, meaning that you can stick to the provided instructions above.


What to expect:

What’s specific about these products is that they are designed to be mixed with creams or serums to create the desired concentration for your skin tolerance and goals.

Niacinamide is water soluble, so it can be easily incorporated into water-based skincare.

The Ordinary’s 100% Niacinamide Powder can be blended with any water-based treatment that is non-conflicting and has a pH between 5.0 and 7.0.

The Ordinary offers several water-based bases that can be used with this powder, including Hyaluronic Acid 2% + B5, Natural Moisturizing Factors + HA, “Buffet” + Copper Peptides 1%, Matrixyl 10% + HA, and my personal favorite – their Marine Hyaluronics.

For example, to create a mixture with a concentration of 10-15% Niacinamide, mix 1/4 scoop of the powder (equivalent to approximately 0.05g) with 4 drops of your chosen base.

On the other hand, the 100% L-Ascorbic Acid Powder is a type of vitamin C in a powdered form.

Similarly to the other powder product, it can be mixed with other skincare such as serums, creams, or moisturizers to customize your vitamin C treatment.

However, depending on the concentration of your mixture, a strong tingling sensation may be experienced during the initial 1-2 weeks of use. This is a normal response to high levels of direct vitamin C exposure and is not typically accompanied by any irritation unless your topmost layer of skin has been compromised.

Over time, your skin’s tolerance to this exposure will increase.

When patch-testing The Ordinary vitamin C or niacinamide powders, make sure to observe the reactions of your skin.

If you notice any negative side effects, try reducing the concentration of the powder significantly or test another brand to see if the results are the same.


Why can these products be irritating:

The potential irritation is mostly a result of the high concentration of the ingredients.

Apart from that, there are always chances that you haven’t mixed the powder well into your base of choice, which can result in a patchy application that irritates the skin.

If you continue seeing reactions even with a reduced powder dose, it’s best to test either the brand’s serums with the same ingredients or look to another brand.


What else to have in mind

In addition, it’s important to consider the following:

  • Check the product’s expiration date to make sure that it’s not old and risky to use;
  • Make sure the packaging is sealed and new, and that the product looks good (without any weird smells, colorings, or other);
  • Check if the product is suitable for your skin type (especially if you have sensitive skin);
  • Make sure you don’t patch test or use other products on the same zone you patch test The Ordinary;
  • Don’t react too negatively and rush to write negative reviews if a certain product has caused a reaction on your skin – this doesn’t necessarily mean that the product is bad or that the ingredient is not suitable for you. It could simply mean that your skin can’t tolerate that specific formulation you’re testing due to one or another reason.

I hope that I’ve helped if you were looking for info on how to do a patch test for The Ordinary range of products.

If that’s the case, your affirmation will mean the world to me, so don’t hesitate to drop me a line.

And if you think that I’ve missed something, do let me know!

Alternatively, you might be interested to learn the optimal way to apply The Ordinary’s Azelaic Acid – it’s a tricky product to incorporate but sooo rewarding! 

Also, make sure to check The Ordinary conflicts guide – some products ought not to be used in the same routine.

There’s a handy PDF to download that doesn’t require your email address 🙂

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