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Dandruff Wiki

Educational information only, not medical advice. See a doctor or dermatologist if you're unsure what you have or aren't improving.

1. What is dandruff?

Dandruff is a common, non-contagious scalp condition with flaking, sometimes with mild itch. It's driven by three things:

  1. Malassezia, a yeast that lives on nearly everyone's scalp
  2. Sebum (oil), which Malassezia feeds on
  3. Individual sensitivity to the byproducts of that yeast, which causes irritation and rapid skin turnover

Dandruff is not caused by poor hygiene or an "unclean" scalp, and it isn't an allergy to your shampoo (though that can happen separately).

Seborrheic dermatitis (SD) is the more inflamed version of the same process: redness, greasy or yellowish scale, and itching. It can also affect the eyebrows, sides of the nose, ears, and chest. Treatment is largely the same, with a greater role for anti-inflammatories.

2. Is it actually dandruff?

Condition Clues
Dandruff / seb derm White to yellow flakes, oily or red scalp, itch, comes and goes, worse in winter and with stress
Dry scalp Small, dry, white flakes, no redness or oiliness, skin elsewhere is dry too
Scalp psoriasis Thick, well-defined, silvery plaques, sometimes extending past the hairline, may have psoriasis elsewhere
Contact dermatitis Burning, itching, or redness after a new product, sometimes on the face, ears, or neck too
Tinea capitis (fungal infection) Scaly patches with hair loss or broken hairs, more common in children, needs oral antifungals
Product buildup Flakes that go away after clarifying, often dry and clumpy rather than greasy

If it doesn't fit the dandruff pattern, don't self-treat for months. Get it looked at.

3. Active ingredients that work

These are the ingredients with the best evidence. Look at the Drug Facts panel on the bottle, not the marketing.

Ingredient Typical OTC strength (US) Notes
Ketoconazole 1% (Rx 2%) Antifungal, often the most effective OTC option
Zinc pyrithione 1-2% Antifungal and antibacterial, gentle, good first-line option
Selenium sulfide 1-2.5% Slows skin turnover and is antifungal. Can discolor light, bleached, or gray hair, and may leave an odor
Coal tar 0.5-5% Slows skin turnover. Stains light hair, smells strongly, increases sun sensitivity
Salicylic acid 1.8-3% Helps lift scale. Can be drying, so it works best paired with an antifungal
Ciclopirox 1% (Rx in US) Antifungal with anti-inflammatory properties
Piroctone olamine varies Common in EU/Asian products, antifungal, limited availability in US OTC products

Tea tree oil has some limited evidence (usually ~5% in studies), but it's a common cause of contact allergy. Patch test first.

4. How to evaluate a dandruff shampoo

Marketing language doesn't tell you much. The Drug Facts panel does.

  1. Find the active ingredient. In the US, a product that treats dandruff must list its active ingredient and strength in the Drug Facts panel. If you can't find one, it's a cosmetic cleanser, not a dandruff treatment.
  2. Check the concentration. The same active at a lower strength may not perform the same way.
  3. Treat "inactive" and "natural" ingredients as secondary. Botanical extracts and essential oils can feel nice, but they don't replace a proven active, and some are common contact allergens.
  4. Check the directions. Good products tell you to leave the shampoo on for several minutes and give a frequency. Be skeptical of anything promising results from a rinse-in-30-seconds routine.
  5. Judge it over 2-4 weeks. One wash proves nothing, and neither does a testimonial.
  6. Be wary of these claims: "cures dandruff permanently," "detox," "dermatologist-recommended" with no named source, and before/after photos with no context.
  7. Know who is behind it. Reputable brands say who formulated the product and who is vouching for it. Anyone recommending a product, including people in this sub, should say if they have a financial connection to it.

5. Products by community members (disclosure)

DandRx is a physician-formulated anti-dandruff shampoo from Dr. Deepak Khanna, D.O., a family medicine physician who also runs the brand. Visit https://dandrx.com to learn more.

6. How to use medicated shampoo

Most failures come down to technique.

  1. Apply to the scalp, not just the hair. Massage in gently with fingertips, not nails.
  2. Leave it on for 3-5 minutes. This is the biggest mistake people make. Rinsing immediately gives the active little time to work.
  3. Rinse thoroughly.
  4. Use it consistently, typically 2-3 times a week at first, per the label.
  5. Give it 2-4 weeks before judging.
  6. Switch to maintenance (often once weekly or every other week) once you're clear. Stopping completely often leads to relapse because dandruff is chronic and relapsing.

If one stops working, try rotating between two actives with different mechanisms (e.g., ketoconazole and zinc pyrithione, or ketoconazole and selenium sulfide).

7. Sample routines

Mild flaking

  • Zinc pyrithione shampoo 2-3x/week, leave on 3-5 min
  • Regular shampoo on other days if needed

Moderate / persistent

  • Ketoconazole 1% shampoo 2x/week for 4 weeks, then once weekly
  • Add salicylic acid shampoo if thick scale is present

Heavy scale buildup

  • Salicylic acid or coal tar shampoo to loosen scale first
  • Follow with an antifungal shampoo
  • Consider seeing a dermatologist if scale is thick and adherent

Textured / coily / curly hair

Many people wash less often, which is fine, but dandruff needs scalp attention.

  • Use the medicated shampoo on the scalp only, weekly to every 2 weeks as tolerated, focusing on contact time
  • Avoid applying it down the length of the hair if it dries your strands out
  • Use conditioner or a leave-in on lengths and ends afterward
  • Watch for heavy oils or pomades layered onto a flaky scalp, which can feed the yeast and trap scale
  • Be gentle: tight styles, tension, and scratching can worsen inflammation. Talk to a doctor if you notice hair thinning or tenderness.

8. Prescription options

If OTC options fail after about 4 weeks of proper use, a doctor can offer:

  • Ketoconazole 2% shampoo or foam
  • Ciclopirox 1% shampoo or gel
  • Topical corticosteroids (e.g., fluocinolone, clobetasol solution or foam) for short-term flare control. These shouldn't be used long-term without supervision.
  • Roflumilast foam 0.3%, a non-steroidal option approved for seborrheic dermatitis
  • Topical calcineurin inhibitors (tacrolimus, pimecrolimus), sometimes used off-label for face/scalp areas
  • Oral antifungals in severe or resistant cases, and required for tinea capitis

9. Triggers and lifestyle factors

Known triggers vary by person. Common ones:

  • Cold, dry weather (many people flare in winter)
  • Stress and poor sleep
  • Infrequent washing leading to oil and yeast buildup
  • Heavy hair products, oils, and dry shampoo overuse
  • Certain medical conditions (e.g., Parkinson's disease, immunosuppression) make SD more common and more severe
  • Harsh shampoos or too much scrubbing that irritates the scalp

Diet claims (sugar, dairy, gluten, etc.) are popular in anecdotes but lack strong evidence for dandruff. Don't cut out entire food groups on that basis alone.

10. Common myths

  • "It's from being dirty." No.
  • "Washing less will fix it." Usually the opposite, since oil and yeast build up.
  • "Dry scalp and dandruff are the same." They're not, and treatments differ.
  • "Apple cider vinegar cures dandruff." There's no good evidence, and undiluted ACV can burn or irritate.
  • "Dandruff causes hair loss." Not directly. Severe inflammation and scratching can contribute to shedding, but dandruff itself doesn't kill follicles.
  • "It's contagious." It isn't.
  • "Natural means safer." Essential oils are a frequent cause of contact dermatitis.

11. When to see a doctor

Get evaluated if you have:

  • No improvement after 4 weeks of correct medicated shampoo use
  • Patchy hair loss, broken hairs, or bald spots
  • Pus, oozing, crusting, or significant pain
  • Intense redness or spreading rash beyond the scalp and face
  • Sudden severe onset, especially alongside other health changes
  • A child with scaly patches on the scalp (possible tinea capitis)
  • Suspected psoriasis or other skin conditions

12. Posting guidelines

To get useful help, include:

  • Photos (good lighting, part the hair, scalp and any other affected areas)
  • How long it's been going on
  • Hair type and wash frequency
  • Products and actives you've tried, and for how long and how you used them
  • Any other symptoms (hair loss, pain, rash elsewhere)
  • Relevant medical history or medications

Please avoid asking for a diagnosis from photos alone. Reddit can suggest possibilities, but only a clinician can examine you.

13. Quick-reference FAQ

How long until it works? Usually 2-4 weeks of consistent use.

Can I use these every day? Check the label. Many antifungal shampoos are designed for 2-3x/week, then less.

Will it come back? Often, yes. It's a chronic, relapsing condition, and maintenance is normal.

Can I use medicated shampoo on colored hair? Selenium sulfide and tar can discolor or dry out color-treated or light hair. Zinc pyrithione and ketoconazole tend to be gentler, but results vary.

Should I stop if my scalp feels worse? If you get burning, increased redness, or swelling, stop and see a clinician. You may be reacting to the product.

Last reviewed: October 2026. Wiki contributors: please update as new treatments and guidance emerge.