How Malassezia Causes Dandruff

How Malassezia Causes Dandruff

Dandruff isn’t just about dry skin, it’s largely caused by a microscopic yeast called Malassezia. Understanding how it works helps you treat dandruff more effectively and keep your scalp balanced.

What Is Malassezia?

Malassezia is a type of yeast that naturally lives on human skin, especially in oily areas like the scalp, face, and chest. It feeds on sebum (natural scalp oil) and, in small amounts, it’s harmless. But when it grows out of control, it can trigger inflammation and flaking known as seborrhoeic dermatitis, the same process behind dandruff.

This yeast plays a key role in both dandruff and seborrhoeic dermatitis by breaking down oils on the skin into fatty acids that can irritate and inflame the scalp.

Where It Appears

  • Scalp and hairline
  • Eyebrows and sides of nose
  • Behind ears
  • Chest and upper back
  • Armpits and groin (in some cases)

These are the same areas rich in sebaceous (oil) glands, providing the perfect environment for Malassezia to thrive.

Common Symptoms of a Malassezia Overgrowth

  • White or yellow flakes on scalp or eyebrows
  • Itching and irritation
  • Red or greasy patches of skin
  • Occasional soreness or sensitivity

If symptoms persist or worsen, it may indicate seborrhoeic dermatitis,  a chronic inflammatory condition triggered by Malassezia overgrowth.

Having a healthy scalp means your hair can look it's best

How Does Malassezia Cause Dandruff?

The yeast feeds on scalp oils, breaking them down into substances that irritate the skin. Here’s what happens:

  1. It Feeds on Sebum: Malassezia thrives on the natural oils of your scalp.
  2. It Produces Oleic Acid: When it digests these oils, it releases oleic acid, a by product that can irritate the outer skin layer in sensitive people.
  3. It Disrupts the Skin Barrier: The acid penetrates the skin barrier, causing inflammation and increased cell turnover, leading to flakes.
  4. It Triggers Immune Response: Your immune system reacts to the irritation, creating redness, itching, and scaling, the classic signs of dandruff.

Not everyone reacts to Malassezia the same way, some people’s scalps are more sensitive to the byproducts, which is why dandruff varies from person to person.

How to Treat & Manage Malassezia-Related Dandruff

  1. Use Antifungal Shampoos: Ingredients such as piroctone olamine, ketoconazole, or selenium sulphide reduce yeast growth and inflammation.
  2. Cleanse Gently: Wash the scalp regularly with a mild, non-soap shampoo to control oil buildup without stripping the skin.
  3. Moisturise: Light emollients like E45 or Doublebase can help restore the scalp barrier and reduce dryness.
  4. Avoid Triggers: Stress, harsh hair products, and infrequent washing can worsen yeast growth and irritation.
  5. Consistency Is Key: Dandruff is a long-term condition, regular use of antifungal products helps maintain balance.
  6. When to See a Doctor: If dandruff spreads, causes significant redness, or doesn’t respond to over-the-counter treatments, see your GP or a dermatologist.

Learn more from Bupa UK and the British Association of Dermatologists.

Quick Summary

  • Malassezia is a yeast that naturally lives on the scalp but can overgrow in oily conditions.
  • It causes irritation and flaking by breaking down scalp oils into fatty acids.
  • Treatment includes antifungal shampoos, gentle cleansing, and regular scalp care.
  • If symptoms persist, seek advice from a dermatologist.

References

 

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