Yeast in Skin Care Products- Good or Bad?

Yeast is a surprise ingredient in many skincare products—but is it safe? You might wonder: aren’t preservatives supposed to kill yeast and microbes in creams and serums? So why would a company deliberately include yeast in skin care? Will it lead to fungal acne? 

Let’s unpack this.

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Fungal acne—technically called pityrosporum folliculitis—is an infection in the hair follicles caused by an overgrowth of Malassezia yeast. It’s often mistaken for traditional acne because it looks very similar: small, red, itchy bumps that tend to cluster, especially on the chest, back, and sometimes the face.

You’ve probably seen this talked about all over Reddit and skincare forums, where it gets a lot of attention. But I can tell you from my own clinical experience practicing dermatology in hot, humid Miami for over 25 years—I’ve only encountered a handful of true fungal acne cases. It’s definitely not as common in real life as online discussions might lead you to believe.

Seborrheic dermatitis is a common skin condition caused by the yeast Malassezia furfur. It leads to redness and flaking, especially between the eyebrows, on the sides of the nose, and on the scalp.

You might be surprised to see “yeast” listed on the ingredient label of your skincare products. As a dermatologist, I get this question all the time: “Why would you put yeast in a face cream?” It’s a fair question—after all, we try to avoid yeast overgrowth on the skin, especially in conditions like fungal acne or seborrheic dermatitis.

But here’s the key thing to understand: the yeast used in skincare isn’t alive. These are not active, growing yeast organisms. Instead, what you’ll see in ingredients lists are either ferments or lysates —and both are processed in ways that make them safe and useful for the skin.

Let me explain the difference:

• Ferments are the byproducts left behind after yeast (or bacteria) ferment a substance—like rice or plant sugars. Think of it like kombucha for your skin.

• Lysates are extracts made from yeast cells that have been broken apart. They’re completely deactivated and can’t grow or multiply.

Some of the most common types of yeast and bacteria used to make these ferments and lysates include Saccharomyces, Lactobacillus, Leuconostoc , Galactomyces, and sometimes Bifidobacterium .

I know this can sound confusing, especially with so much chatter on places like Reddit about fungal acne and whether these ingredients are triggers. One Reddit user put it well:

“The yeast used in skincare is deactivated or dormant yeast… if it were active, bottles would be exploding on shelves from gas buildup!”

And they’re right—these yeast-derived ingredients are very stable and don’t grow in your products or on your skin. In fact, many people with sensitive skin—or even those prone to fungal acne—find that some yeast lysates, like the popular one Saccharomyces ferment, work well for them. Others may react and get a rash to these.

These yeast-derived ingredients aren’t just safe—they actually do some great things for your skin. Here are a few of the most common ones, along with why I recommend them in certain skincare routines:

•  Galactomyces – This ferment comes from Galactomyces candidum, a yeast originally used in sake production. It’s rich in amino acids, peptides, vitamins, and enzymes that support skin brightening, hydration, and barrier repair. It may contain residual fungal proteins and nutrients that could feed Malassezia—the yeast responsible for fungal acne. (This is not proven.) This has led to anecdotal reports on Reddit, of Galactomyces triggering breakouts in individuals prone to fungal acne. While this connection hasn’t been confirmed by peer-reviewed research, I typically recommend caution for patients with a history of fungal acne.
  

• Lactobacillus – This one comes from probiotic fermentation and helps with skin repair. It boosts collagen production by activating fibroblasts and improves hydration in the outer skin layer (the stratum corneum), which can help reduce fine lines.

• Leuconostoc – Often listed as Leuconostoc/Radish Root Ferment Filtrate, this has mild antimicrobial properties. It helps preserve the product naturally and also supports a healthy balance of skin microbes. It’s gentle and hydrating—great for acne-prone or sensitive skin types.

• Saccharomyces – This is one of my favorites. It’s an antioxidant-rich lysate that boosts energy production in skin cells and helps renew and repair the skin barrier. I often use this in regimens for patients looking to improve radiance and overall skin vitality.

Here’s where the fermentation process really shines. When yeast or bacteria ferment a substance, they break it down into smaller, more bioavailable pieces. That means your skin can actually use it better because it can penetrate into the skin.

When Saccharomyces yeast is used in fermentation, it produces peptides , B-complex vitamins (like B1, B2, B3, and B5), amino acids , enzymes , organic acids (such as lactic acid), and beta-glucans . These ingredients work together to support skin health. The peptides and amino acids help repair the skin barrier and promote collagen synthesis. B vitamins play critical roles in cellular metabolism and DNA repair. For instance, niacinamide (B3) improves barrier function and reduces inflammation.

The popularity of yeast lysates and ferments in skin care has led to some confusion—especially when people hear the word "yeast" and immediately think of infections from fungus.  

Let me clear that up. Yes, you definitely want to avoid live yeast growing on your skin, and no, you don’t want mold or contamination in your skincare products. But that’s not what these ingredients are. Yeast-derived ingredients like ferments and lysates are carefully processed and completely deactivated—they’re not alive and can’t grow or reproduce. What they can do is deliver powerful, skin-friendly compounds that help with everything from hydration to antioxidant protection. 

You won't see “yeast” on a product label. Instead you will see the species name followed by "ferment or lysate". These ingredients are among the newest developments in modern skin care. When formulated properly, they’re safe.

It's really too early to know if these ingredients are really effective as no controlled evidence based studies have been done.

Looking for the best skin care products? Step 1 is to identify which of the 16 skin types you are by taking our quiz.  Then we can give you personalized skin care advice.

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