If there is one skincare ingredient people seem to simultaneously love, fear, and completely misunderstand, it’s retinoids. 

You’ve probably heard some version of: 

“Everyone should be using a retinol.” 

“Tretinoin is the strongest, so it’s obviously the best.” 

“If you’re peeling, that means it’s working.” 

“You have to push through the purge.”

Or my personal favorite: 

“I’m using a 1% retinol, so it’s basically the same as tretinoin.”

Not quite. 

Retinoids are genuinely fascinating ingredients. They’re also among the most extensively studied topical ingredients we have for acne and photoaged skin. 

But somewhere between dermatology, cosmetic formulation, social media, and skincare marketing, “retinoid” became a catch-all word for several molecules that don’t behave exactly the same way. 

And understanding those differences matters. 

Because with retinoids, stronger isn’t automatically better. 

More frequent isn’t automatically better. 

And irritation definitely isn’t the goal. 

Let’s start at the beginning. 

First things first: what is a retinoid? 

Retinoid is the umbrella term for a family of compounds related to vitamin A. 

Retinol is a retinoid. 

Retinaldehyde - usually called retinal - is a retinoid. 

Tretinoin is a retinoid. 

Adapalene is a retinoid. 

So when someone says “retinal” and “retinoid” interchangeably, they’re technically talking about two different things. 

All retinols are retinoids. 

Not all retinoids are retinol. 

Think of retinoid as the family name. Retinol is just one member of the family, and some family members are considerably more powerful than others. 

Why does vitamin A matter to the skin? 

This is where retinoids become much more interesting than simply being a “wrinkle ingredient.” 

Retinoids influence cellular behavior. 

Ultimately, active retinoic acid interacts with retinoic acid receptors inside cells, influencing gene expression and processes involved in cellular differentiation, proliferation, inflammation, and extracellular matrix regulation. 

In practical terms, depending on the specific retinoid and condition being treated, retinoids can influence: 

• Abnormal follicular keratinization involved in acne 

• Comedone formation

• Epidermal turnover and differentiation 

• Pigmentation irregularities 

• Fine lines and photodamage 

• Collagen metabolism 

• Skin texture 

This is why the same broad family of ingredients can appear in conversations about acne, aging, texture, and pigmentation. 

They’re not simply exfoliating the surface. 

They’re influencing how skin cells behave. 

Retinoids are not exfoliants

I really want this one to sink in. 

Retinoids are not traditional exfoliating acids. 

They frequently get grouped with glycolic acid, lactic acid, and salicylic acid because all of them can make skin flaky or irritated. 

But they don’t work the same way. 

Exfoliating acids primarily influence cohesion and shedding at or near the surface, depending on the acid and formulation. 

Retinoids influence cellular processes through retinoid receptors. 

Can retinoid use result in visible peeling? 

Absolutely. 

But peeling is a side effect, not the mechanism we’re chasing. 

Your tretinoin isn’t successful because your face is falling off. 

I promise. 

Retinol - Retinal - Retinoic Acid 

Now we get to the part everyone sees in skincare diagrams. 

For certain cosmetic retinoids to exert retinoic-acid-mediated effects, they must undergo conversion within the skin. 

A simplified pathway looks like this: 

Retinol - Retinaldehyde - Retinoic Acid 

Retinol requires two oxidation steps. 

Retinaldehyde requires one. 

Retinoic acid - such as tretinoin - is already in the biologically active form that binds nuclear retinoic acid receptors. 

This helps explain why tretinoin is generally more potent and more predictable than cosmetic retinol. 

It doesn’t need to make those same conversion steps first. 

But - and this is important - 

Potency isn’t the only thing that determines whether something is a good skincare choice. 

Tolerability matters too. 

Retinol: the famous one

Retinol is probably the retinoid most consumers recognize. 

It’s widely available in over-the-counter cosmetic products and can be an excellent option for someone who wants the benefits of a retinoid without immediately jumping to a prescription. 

Once applied, retinol must be converted first into retinaldehyde and then into retinoic acid. 

That makes its activity less direct than tretinoin. But don’t mistake “less potent” for “useless.” 

Well-formulated retinol products can absolutely influence photoaging and skin appearance with consistent use. 

The key phrase there is: 

Well-formulated

Retinol is notoriously sensitive to things like light and oxidation, so packaging, formulation, stabilization, and delivery systems matter tremendously. 

A percentage on the front of a bottle tells you far less than people think it does. 

Retinal: the middle child that deserves more attention 

Then we have retinaldehyde, usually marketed as retinal. 

The retinal sits one conversion step away from retinoic acid. 

Because of that, it occupies an interesting space between traditional cosmetic retinol and prescription retinoic acid. 

It’s become increasingly popular in skincare formulations, and personally, I think it’s one of the more interesting retinoids to watch. 

But again: 

A retinal product isn’t automatically superior because the retinal is closer to retinoic acid. 

The finished formulation still matters. 

Stability matters. 

Delivery matters. 

Concentration matters. 

And the person using it matters. 

Ingredient hierarchy alone doesn’t build a skincare routine. 

Tretinoin: already active 

And then we arrive at tretinoin, also known as all-trans retinoic acid. 

Unlike retinol and retinal, tretinoin doesn’t need to be converted into retinoic acid. It already is retinoic acid. 

That’s one reason it has such extensive clinical evidence behind it. 

Topical tretinoin has long been used in dermatology for acne and is also well established for improving signs of photodamage with continued use. 

But tretinoin also has a reputation for something else: 

Irritation. 

Dryness. 

Redness. 

Peeling. 

Bruning. 

Those effects can occur, particularly during initiation or when the medication is used too aggressively.

And this is exactly where I see people turn an incredible medication into a miserable skincare experience. 

With any retinoid, the skin barrier needs to be fully intact for it to tolerate the ingredient well. As well as see the results the medication is meant to give. The importance of that isn’t talked about as much and is commonly brushed off or disregarded. 

Adapalene deserves its own introduction 

Adapalene is another topical retinoid, but structurally it’s different from tretinoin. 

It was developed specifically with acne treatment in mind and selectively interacts with certain retinoic acid receptor subtypes. 

In the United States, adapalene 0.1% is available over the counter, while other formulations or strengths may require a prescription. 

It’s particularly useful for comedonal and inflammatory acne and is often considered more tolerable and photostable than tretinoin. 

So when someone asks me: 

“What’s the strongest retinoid?” 

I’m much more interested in asking:

“What are we trying to treat?” 

Because that’s the question that actually matters. 

Let’s talk about “retinization” 

When someone begins a retinoid, particularly a stronger one, the skin may go through an adjustment period sometimes referred to as retinization. 

During this period, someone may experience: 

• Dryness 

• Flaking 

• Mild redness

• Increased sensitivity 

• Irritation 

The intensity varies dramatically between people. 

Some tolerate retinoids beautifully. 

Others need a very gradual introduction. 

And this is where I think skincare culture sometimes gives terrible advice. 

You do not receive an award for suffering through the most aggressive initiation schedule possible. 

The objective is not to prove that your skin can survive tretinoin. 

The objective is to use the medication consistently enough to receive its benefits while keeping irritation manageable. 

Purging is real - but not everything is a purge

Ah, purging. 

Possibly one of the most abused words in skincare. 

Because retinoids influence follicular keratinization and cellular turnover, some acne-prone individuals can experience an initial worsening of breakouts when treatment begins. 

But that does not mean every breakout for the next six months should be dismissed as “purging.” 

If you’re developing: 

• Significant burning 

• Severe redness

• Cracking 

• Widespread irritation 

• Breakouts in completely unusual areas

• Persistent worsening without improvement

I don’t want you to blindly continue because someone online told you that “it get worse before it gets better.” 

Sometimes skin is adjusting. 

Sometimes skin is irritated. 

And sometimes something entirely different is happening. 

Knowing the difference matters. 

More tretinoin is not more tretinoin 

This is another concept I wish everyone understood. 

Using a pea-sized amount of tretinoin across the face is generally enough. Using three peas doesn't triple your results. 

It mostly increases your chances of irritating yourself. 

Retinoids are a perfect example of why skincare dosing matters. We’re trying to create a biological response. 

Once we’ve achieved the appropriate exposure, piling more medication onto the surface isn’t necessarily creating a better response. 

This is skincare. 

Not frosting a cupcake. 

Thin, even application wins. 

And no, the highest percentage isn’t automatically the best

This comes up constantly. 

People want to graduate: 

0.025%

Then 0.05%

Then 0.1%

As though skincare has levels you need to unlock. 

The goal is to achieve the desired clinical outcome. 

If someone is doing beautifully on a lower strength, tolerating consistently, and achieving the response we’re looking for, I don’t automatically see a reason to increase simply for the sake of increasing. 

A stronger concentration that you can only tolerate sporadically may be less useful to you then a lower concentration you can use consistently. 

Consistency usually matters more than bragging rights. 

Your barrier still matters 

If you’ve read my Skin Education Journals, you knew I was going to bring this up eventually. 

Retinoids do not exist in a vacuum. 

The condition of the skin barrier matters enormously when we’re deciding retinol use, how to introduce them, and percentages. 

If someone’s skin is already: 

Burning

Flaking 

Dehydrated

Inflamed

Reacting to everything 

I’m probably not thinking: 

“You know what this needs? Maximum-strength tretinoin seven nights a week.” 

We have to look at the skin in front of us. 

A healthy, resilient barrier generally gives us much more room to work. 

This doesn’t mean you need “perfect” skin before using a retinoid. 

It means tolerability is part of treatment success. 

How I like to introduce retinoids 

There isn’t one universal schedule that works for everyone. 

But generally I prefer low and slow over aggressively introducing a retinoid and then spending the next month trying to undo the irritation. 

Depending on the retinoid, formulation, prescription instructions, and individual skin, this may involve beginning with limited weekly applications and gradually increasing frequency as tolerated. 

I also pay attention to the rest of the routine. 

If we’re introducing a retinoid, I don’t want someone simultaneously starting: 

A new exfoliating acid. 

A strong benzoyl peroxide product. 

Three brightening serums. 

And a peel. 

How could we even know what’s causing what? 

Change one variable. Watch the skin. Adjust. That’s much more useful information. 

The "sandwich method” 

You’ve probably heard of applying moisturizer before and after a retinoid – the so-called sandwich method. 

For some people, applying moisturizer before a potentially irritating retinoid can reduce irritation while they’re adjusting. 

Will this make your retinoid completely ineffective? 

No. 

And I’d much rather have someone use a tolerable routine consistently than repeatedly irritate their skin because they’re afraid moisturizer will somehow “block” everything. 

That said, prescription medications should ultimately be used according to the directions provided by the prescribing clinician. 

Skincare should complement medical treatment - not rewrite it. 

What about the eyes, nose, and mouth? 

These areas deserve extra attention because they’re often prone to irritation. 

Retinoids can migrate slightly after application, and the creases around the nose, corners of the mouth, and eye area may become irritated even when you didn’t intentionally apply much product there. 

Depending on the person and prescription instructions, protecting vulnerable areas with moisturizer or an occlusive beforehand can sometimes improve tolerability. 

This is one of those tiny technique changes that can make a surprisingly large difference. 

Retinoids and sunlight 

Here’s another misconception: 

“You can’t use retinoids because they make your skin photosensitive forever.” 

The relationship is more nuanced than that. 

Some retinoids are photolabile, meaning light can degrade the molecule, which is one reason certain formulations are recommended for evening application. 

Early retinoid irritation can also leave skin more vulnerable and uncomfortable with environmental exposure. 

But regardless of whether you use a retinoid, daily broad-spectrum sunscreen matters. 

If we’re using a treatment to improve photodamage while continuing to accumulate significant UV damage every day, we’re working against ourselves.

Treat the skin. 

Protect the skin. 

Both matter. 

Retinoid and pigmentation 

Retinoids can also play an important role in certain pigmentation treatment plans. 

By influencing epidermal turnover and other cellular processes, they may help improve uneven pigmentation, they may help improve uneven pigmentation and are sometimes combined with other pigment-targeting therapies. 

But pigment is complicated. 

Melasma isn’t the same as post-inflammatory hyperpigmentation. 

PIH isn’t the same as solar lentigo. 

And irritation itself can worsen pigmentation– particularly in skin prone to PIH changes. 

Which brings us right back to tolerability, aggressiveness isn’t always faster. Sometimes aggressiveness creates another problem for us to treat. 

Retinoids and collagen 

This is probably where retinoids earned their anti-aging reputation. 

With long-term use, topical retinoids - particularly tretinoin, which has extensive evidence – can influence dermal extracellular matrix remodeling, including pathways involving collagen production and degradation. 

This doesn’t mean applying tretinoin suddenly fills wrinkles with brand-new collagen overnight. 

Biology takes time. 

Changes related to photodamage occur gradually over months of consistent use. 

That’s another reason I don’t judge a retinoid after three weeks. 

We’re influencing cellular behavior. 

We’re not applying a filter. 

Retinoids aren’t for everyone, all the time

Despite how they’re discussed online, retinoids aren’t a mandatory requirement for having healthy skin. 

Certain people may not tolerate them well. 

Certain skin conditions may require additional consideration. 

Prescription retinoids require appropriate medical guidance. 

And retinoids are generally avoided during pregnancy; anyone pregnant, planning pregnancy, or breastfeeding should discuss retinoid use with their healthcare professional. 

There are also situations where I may intentionally reduce or pause retinoid use around certain professional procedures. 

Context matters. 

Again: 

The ingredient doesn’t make the decision. 

The skin does. 

Why this matters as a provider 

When someone tells me they’re using a retinoid, I don’t simply write down “tretinoin” and move on. 

I want to know: 

What retinoid? 

What strength? 

What formulation? 

How often? 

For how long? 

What else are you using? 

How does your skin feel the next morning? 

Are you peeling? 

Are you burning? 

Are you actually tolerating it? 

Because two clients can both tell me: 

“I use tretinoin.” 

One may be using 0.025% twice weekly with a beautifully supported barrier. 

The other may be using 0.1% every night while exfoliating every morning and wondering why water suddenly burns their face. 

Those aren’t the same situation. And I would never treat them like they are. 

Final Thoughts 

Retinoids deserve their reputation. 

They’re some of the most interesting and well-studied ingredients we have in skincare and dermatology. 

But I think we do them a disservice when we reduce the entire conversation to: 

“Which one is the strongest?” 

Because the best retinoid isn’t necessarily the strongest one you can get your hands on. 

It’s the one appropriate for your concern, your skin, and your ability to use it consistently. 

Retinol can be valuable. 

Retinal can be valuable. 

Adapalene can be valuable. 

Tretinoin can be incredibly valuable. 

They’re tools. 

And like every tool in skincare, their success depends on how intelligently we use them. 

You don’t need your skin to peel to prove your retinoid is working. 

You don’t need to race toward the highest concentration. 

And you don’t need to sacrifice your barrier in pursuit of faster results. 

Skin biology doesn’t reward impatience. 

Give it the right signal. 

Give it enough time. 

And give it the opportunity to respond. 

Journal Notes 

I think retinoid are the perfect example of something I repeat constantly: 

More isn’t always better. Better is better. 

The goal isn’t the strongest prescription. 

The goal isn’t seven nights a week. 

And the goal definitely isn’t peeling. 

The goal is creating a meaningful biological change while maintaining skin that’s healthy enough to tolerate the process. 

Once you start thinking about retinoids that way, the question changes from: 

“How strong can I go?” 

To: 

“What’s the smartest way to get where I’m trying to go?” 

And that’s a much better question.