Everything You Need to Know About Dandruff, According to Dermatologist Dr James Kilgour

Dealing with dandruff? You’re not alone—it's a common scalp concern. Thankfully, our in-house dermatologist is here to provide expert answers to your questions!

What Causes Dandruff, and How Does It Contribute to Hair Thinning?

Dandruff, or seborrheic dermatitis as it's medically known, is caused by an inflammatory reaction to Malassezia, a type of fungus naturally present in our scalp's skin flora. For some, this fungus triggers an inflammatory response that leads to dandruff, itching and redness. Even if visible signs of inflammation aren't present, Malassezia can still cause low-level "inflammaging" of the scalp over time, which can contribute to hair thinning and even hair loss.

What Are the Signs of Dandruff?

The typical signs of dandruff include greasy white flakes (often visible on dark-coloured clothing), persistent itchiness and redness. While dandruff mainly affects the scalp, it can also show up in other areas like behind the ears, around the nose folds, the eyebrows, and in some cases, the chest, armpits, and groin.

Dandruff vs. Dry Scalp

A dry scalp is similar to dry skin, while dandruff is more like a rash. A dry scalp may cause mild itchiness and slight flaking, while dandruff tends to be more inflammatory, leading to intense itching, significant flakiness, and redness. In some cases, scalp psoriasis can look similar to dandruff, so it's always wise to consult with a dermatologist for an accurate diagnosis.

How Can You Treat Dandruff?

Dandruff can be managed with both over-the-counter and prescription medicated shampoos. For more severe cases, a mild topical steroid solution may be required to reduce inflammation—this should be discussed with your physician.

What to Look for in a Dandruff Shampoo

When it comes to dandruff treatment, I frequently recommend prescription-strength 2% Ketoconazole shampoo to my patients. It’s effective and fragrance-free, reducing the risk of irritation. If you’re looking for an over-the-counter option, the 1% version works well. Other helpful ingredients to seek in dandruff shampoos include zinc pyrithione, piroctone olamine (found in The Prevention Scalp Serum by KilgourMD!), and selenium sulfide. To help remove built-up flakes, a shampoo containing salicylic acid works as an excellent gentle scalp exfoliant.

How Often Should You Use Dandruff Shampoo?

For best results, I recommend using an anti-dandruff shampoo like ketoconazole two to three times a week for intensive treatment. Once symptoms improve, reduce the frequency to once a week for maintenance. The key to success is to lather the shampoo and leave it on your scalp for at least five minutes before rinsing.

How Long Does It Take for Dandruff Shampoo to Work?

With the right treatment, you should see noticeable results after just one use, especially with prescription-strength ketoconazole, as long as you follow the five-minute rule before rinsing.