Skin Acids: The Top Ones Every Skincare Lover Should Know (+ Guide to the Best Acids for Acne)

Skin acids have become the buzzword in the beauty industry. “Acids do this, acids do that…” But with so many options, it’s easy to feel overwhelmed. Which acids are best for acne? Will all acids irritate the skin? And do you even need them in your skincare routine?

In short, yes, some acids are worth exploring! It all depends on your skin type and goals.

In this post, we’ll break down the best acids (or acid groups) so you’ll know exactly what each one does and how to choose the right one for your skin. By “best,” we mean the most powerful and versatile—essentially, the stars of the skincare acid world.

1. AHAs (Alpha Hydroxy Acids)

🧴How do you find them on the labels? 

Look for glycolic acid, lactic acid, mandelic acid, and others.

These acids are naturally found in fruits, milk, and sugarcane. For cosmetics, AHAs are typically produced synthetically in labs to ensure purity.

AHAs are water-soluble and don’t penetrate the skin’s oil-rich layers deeply. But don’t let that fool you—they’re not lazy! Even on the surface, they work hard to exfoliate dead skin and clear out pore-clogging debris. Regular use lets you notice smoother skin texture, a brighter complexion, and faded pigmentation and acne marks.

All these effects are backed by research. One study showed that 9 out of 10 volunteers who used AHAs for 3 weeks noticed visible improvements in their skin texture. As another scientific source says, the use of AHA acids gives ”rise to a younger-looking skin.”

AHAs also effectively address signs of sun damage, such as dryness and reduced collagen (not burns!), by boosting hydration and skin renewal.

Same but different?

All AHAs are united by their exfoliating (peeling) and anti-pigmentation properties, but each one offers distinct benefits. For example:

• Mandelic acid is the most versatile AHA for all skin types and can be a great option for those new to skin acids;
• Glycolic acid is your best bet if you’re looking for anti-aging effects, such as smoothing fine lines, in addition to its exfoliating benefits;

• Lactic acid is a part of the Natural Moisturizing Factor (NMF)—a group of substances naturally found in your skin that help keep it hydrated and soft. So, why not boost this factor with even more lactic acid? Apart from its exfoliating properties as an AHA, it also has humectant qualities, meaning it attracts and retains moisture in the skin. Because of this, lactic acid is often well-tolerated by dry and sensitive skin.

Remember that the effects of any skin acid—whether anti-aging, brightening, or otherwise—depend on its concentration, the product’s pH level, and its type. The potential for irritation also depends on these factors: the higher the concentration and the lower the product’s pH, the greater the irritation is likely to be.

☀️ Do they boost photosensitivity? YES

This means AHAs can make the outer layer more likely to burn, get irritated, or develop pigmentation when exposed to UV rays. To avoid this, always wear broad-spectrum SPF 50 or 50+ sunscreen if using these acids. Apply them at night to minimize risk, and use hats and sunglasses for extra protection.

2. BHAs (Beta Hydroxy Acids)

🧴How do you find them on the labels? 

Look for salicylic acid, beta hydroxybutanoic acid, and others.

Before we dive into BHAs, do you know someone who just loves cleaning? And not just dusting surfaces or making the bed. We mean deep cleaning, rifling through old clothes, and wiping the narrowest corners that have never seen sunlight.

If that kind of deep cleaning sounds familiar, think of BHAs the same way—they don’t just clean the surface; they go deep. They’re oil-soluble, meaning they can get into pores and thoroughly clean them. This makes them effective for treating issues like acne, blackheads, and clogged pores. Besides, they’re strong for fading post-acne marks.

Who will find them the most beneficial?

If you have oily, acne-prone skin and deal with frequent breakouts, BHAs could boost your routine.

But remember, not all acne-prone skin will tolerate BHAs—salicylic acid, looking at you! They may irritate sensitive or dry skin, causing itching and peeling. Always patch-test any product containing BHAs on a small area before applying it more liberally. If a reaction occurs at the patch test site, maybe it’s just not your skin’s match.

How do you use BHAs?

Over-the-counter products normally have 0.5-2% of an acid. To ease into using BHAs, start by applying the acid-containing product in the evening every other day, then gradually increase to 2-3 times a week. If you don’t notice excessive dryness or peeling, switch to using the product once a day in the evening.

Plus, no matter what type of product you’re using—be it a cleanser, cream, or serum—always follow the provided instructions. As a rule, a higher acid concentration is more effective but also increases the likelihood of skin irritation. The manufacturer knows the exact concentration and provides the best guidelines, even if the concentration isn’t explicitly stated on the label.

For a more profound effect, you might consider in-office BHA peels, which can contain up to 50% concentration (like salicylic acid peels, for example). However, these should only be performed by a healthcare professional and only if they’re truly recommended for your skin.

☀️ Do they boost photosensitivity? YES

This means BHAs can make the outer layer more likely to burn, get irritated, or develop pigmentation when exposed to UV rays. To avoid this, always wear broad-spectrum SPF 50 or 50+ sunscreen if using these acids. Apply them at night to minimize risk, and use hats and sunglasses for extra protection.

Rooting for plant-based ingredients?

Willow bark extract is a milder yet less potent alternative to salicylic acid. As a natural source of salicin—the compound behind salicylic acid’s effectiveness—it offers antibacterial and anti-inflammatory benefits. These properties help refine pores and reduce the appearance of fine lines.

Phew, that was quite a journey with AHAs and BHAs—thanks for sticking with us! We’ve covered the classics, so now let’s give the spotlight to some lesser-known acids that are still beloved by skincare experts.

3. PHAs (Poly Hydroxy Acids)

🧴How do you find them on the labels? 

Look for gluconolactone, lactobionic acid, maltobionic acid, galactose.

Their molecules are larger than both AHAs and BHAs, which affects how they interact with the skin. You might be thinking, “Interesting chemistry fact, but what does this mean for me?” Simply put, the larger molecules absorb more slowly and stay on the surface longer, making them gentler and less likely to cause irritation—ideal for all skin types.

With regular use of PHAs, you might expect…

• Increased hydration—PHAs can lock in moisture in the skin;
• Increased protection—these acids act as antioxidants, helping combat the effects of external factors like pollution and UV exposure;
• A fuller collagen reserves—as this study suggests, PHAs help preserve skin’s natural collagen, a protein that helps your skin stay firm, plump, and smooth;

• A more even skin tone and cleaner pores.

☀️ Do they boost photosensitivity? NO

This study confirms that PHAs can be safely used during the day, unlike AHAs and BHAs, which are best used at night. However, you should still apply broad-spectrum sunscreen for protection.

4. Azelaic acid

This one is special for a reason. Azelaic acid is one of the few skin acids that can inhibit tyrosinase, the enzyme responsible for the production of melanin (the natural pigment in our skin, hair, and eyes that gives them color). That’s why azelaic acid is strong for fading existing post-acne marks and preventing new dark spots from forming.

Already sounds like a superpower, right? But this acid doesn’t stop there. It kills bacteria that cause acne and gives your skin antioxidant protection (remember the harmful effects of car fumes and other environmental factors?). Besides, the acid keeps your pores from getting clogged and can reduce redness by preventing the widening of your blood vessels.

☀️ Does it boost photosensitivity? YES

You know the drill—the less sun exposure when using this ingredient, the better.

5. Honorable Mentions

• Succinic acid is a powerhouse for balancing and calming the skin.
• Hyaluronic acid is the QUEEN of hydration, keeping skin plump and moisturized—find out more about it here.
• L ascorbic acid (vitamin C) brightens and boosts collagen for a glowing complexion; we’ve covered it in detail here.

Tranexamic acid is a skin tone savior, perfect for tackling discoloration and dark spots.

Guide on Skin Acids and Acne

We know how tough it can be to choose cosmetics when you have acne. On one hand, you don’t want to make things worse; on the other, you want to see improvements. This quick guide can help you select the best acids based on your skin’s needs:

The Finish Line + PIW Formula

Hope you have a clearer understanding of all the acids now and maybe even cherry-picked a few to try in your routine!

Just remember, there are plenty more acids out there—our not having mentioned them here doesn’t mean they’re not effective.

Before you go, here’s a simple way to use acids to your benefit—the PIW formula:

• Patch test: Test the acid-containing product on a small area of your skin to check for any immediate reactions like irritation, redness, or burning;
• Isolate: Use the skin acid by itself, without combining it with other active ingredients (such as retinol, vitamin C, or other exfoliating acids), to avoid overstimulating or damaging the skin;
• Wait: Allow the effects of the acid to build up over time. Sometimes, we just give up right before we see the result! While some positive changes may be noticeable after one night, it’s important to be patient and give the product several uses (typically over a few weeks) to see the full benefits.

If you’re still lost on whether your skin needs acids, consult a healthcare specialist first—knowing your skin type is the crucial first step toward healthier skin.

If you already know your skin type, you can use the OnSkin app to scan products and check if their formulas (which often include acids—popularity is popularity) are suitable for your skin and the benefits you can expect from using them.