Frequently asked questions
What causes dandruff in the first place?
Let us shout it louder for the people in the back: Dandruff is incredibly common and nothing to feel embarrassed about. Also known as seborrheic dermatitis, dandruff is an inflammatory condition that causes the skin of the scalp to become red, dry, and flaky. “Flares are common when the weather turns cold and dry, and stress can also trigger a flare,” says dermatologist Hadley King, MD. She notes that this type of dermatitis can also affect other areas besides the scalp, including the ears, eyebrows, center of the face, eyelids, upper chest, upper back, armpits, and groin area.
“We do not know exactly what causes seborrhea, but it does seem to be multifactorial,” says Dr. King. “These factors may include a yeast that normally lives on our skin (more on this below), our genes, living in a cold and dry climate, stress, and a person’s overall health.”
Some medical conditions may also increase your risk, including HIV, acne, rosacea, psoriasis, Parkinson’s disease, epilepsy, stroke, heart attack, alcoholism, depression, and eating disorders.
What to look for in an anti-dandruff shampoo
Fortunately, there are a wide array of over-the-counter dandruff treatments available—namely anti-dandruff shampoos. As for what kind of ingredients make up the best dandruff shampoos, this is what Dr. King recommends seeking out.
- Selenium sulfide: has antifungal properties; can decrease irritation and itching
- Pyrithione zinc: Has antimicrobial and antifungal properties; also helpful for inflammation and itchy scalp
- Salicylic acid: Helps to reduce scaling on the scalp
- Ketoconazole: Has antifungal and mild anti-inflammatory properties
- Coal tar: Suppresses fungus; decreases inflammation; may reduce sebum production
- Tea tree oil: Has antibacterial, antifungal, and anti-inflammatory properties
If you try using an anti-dandruff shampoo with these ingredients and it’s not working to address your symptoms, then see a dermatologist, who may prescribe a topical cortisone for the scalp or other affected area, says Dr. King.
Is dandruff fungal or bacterial?
“Dandruff is primarily fungal in nature, caused by an overgrowth of Malassezia yeasts rather than bacteria. These lipophilic yeasts are part of the normal scalp microbiome but can proliferate excessively in certain individuals, leading to the inflammatory response that characterizes dandruff,” says Pooja Rambhia, MD, a board-certified dermatologist at Union Derm. The scalp microbiome is complex, though, and bacterial imbalances can contribute to scalp conditions, so it’s best to consult with your board-certified dermatologist to uncover the root cause of your dandruff.
How often should you use dandruff shampoo?
The key with any dandruff shampoo is consistency—but not necessarily daily use, Dr. Rambhia says. “You should use it two to three times per week initially, then taper maintenance as symptoms improve.” Bellemare also notes that washing your hair more frequently in general can help remove excess oil and yeast buildup, which can reduce dandruff overall.
Does dandruff mean your scalp is unhealthy?
The good news is, according to the experts we spoke with, having dandruff does not mean that your scalp is unhealthy. “Dandruff is a common condition affecting up to 50% of people,” says Dr. Rambhia. “It occurs when there’s an imbalance in the normal scalp microbiome combined with individual genetic susceptibility, rather than poor hygiene or disease.”
It is important to note, though, that dandruff does involve chronic low-grade inflammation and compromised barrier function, which can affect scalp health over time. “Left untreated, this inflammatory state may contribute to other scalp issues, including potential hair thinning due to follicular inflammation. With appropriate medicated shampoos and consistent care, the scalp microbiome can be rebalanced and healthy function restored. Dandruff is a manageable condition, not a sign of overall scalp disease,” she says.
What should you avoid doing if you have dandruff (i.e., picking or scratching, etc.).
It’s very important to avoid a few things if you have dandruff, Dr. Rambhia says. “First, do not scratch or pick at it, as this can worsen inflammation, damage the scalp’s barrier, and even lead to secondary bacterial infections.” Next, don’t skip shampooing, and minimize heavy styling products (such as oil-based gels and sprays). “I’d also avoid olive oil scalp treatments, as they can worsen dandruff, and limit harsh chemical treatments like frequent coloring, bleaching, or aggressive styling. These can all contribute to disrupting the natural barrier function and trigger inflammatory flare-ups.”
Tips for removing dandruff fast
“While the fastest fix is using a medicated or prescription shampoo, consistent and regular use of an anti-dandruff shampoo can make a dramatic difference,” says Bellemare. She also recommends making sure your hair is fully blow-dried before bed because sleeping with damp hair can exacerbate scalp issues and contribute to flaking.
How we evaluated dandruff shampoos
We tested dandruff shampoos by evaluating ingredients according to dermatologists. Glamour contributors applied shampoos for a couple of weeks and noted textures, how well they lathered and washed out, and whether they were really able to keep flaking and itching at bay. The best ones that met following criteria:
- Ingredients: Contained selenium sulfide, pyrithione zinc, or exfoliating salicylic acid to help rid dead skin cells and give us a more clarified, clean scalp.
- Texture and wash: Had a lightweight texture that easily lathered and washed out without leaving residue behind.
- Efficacy: Successfully got rid of flakes and itching over a span of days to weeks, and were effective in making our hair look clean and residue-free.
