Dandruff: why it keeps coming back
Dandruff is the most self-treated scalp condition and one of the most misunderstood. The central error is thinking of it as dryness — which leads to the exact treatment that makes it worse.
Let me correct the central misunderstanding immediately. Dandruff is not caused by a dry scalp. It is caused by an inflammatory reaction to Malassezia, a yeast that lives on everyone's skin and thrives on sebum. Dandruff is the mild end of a spectrum; seborrhoeic dermatitis is the same process, more severe.
This is why the traditional response of applying more coconut oil makes it worse — you are feeding the organism causing the problem. In Kerala's humidity, where Malassezia flourishes anyway, this is one of the most common mistakes I correct.
Is it actually dandruff?
| Condition | Distinguishing features |
|---|---|
| Dandruff / seborrhoeic dermatitis | Greasy yellowish flakes, itch, redness. Also affects eyebrows, sides of nose, behind ears, chest. |
| Dry scalp | Small white dry flakes, tight feeling, no greasiness or redness. Improves with moisturiser. |
| Scalp psoriasis | Thick, silvery, well-defined plaques extending past the hairline. Often nail changes or elbow/knee patches too. |
| Tinea capitis | Scaly patches with hair breakage or bald areas. Common in children; needs oral antifungals, not shampoo. |
| Contact dermatitis | Started after a new dye, shampoo or oil. Itchy, sometimes weeping. |
The shampoo ingredients that work
Read the active ingredient, not the brand name or the marketing. These are the ones with evidence:
- Ketoconazole 2% — the most effective antifungal shampoo. Usually my first choice.
- Zinc pyrithione 1–2% — antifungal and anti-inflammatory. Good for regular maintenance.
- Selenium sulphide 2.5% — effective; can discolour treated or light hair.
- Ciclopirox olamine — a good alternative antifungal.
- Salicylic acid — removes scale but does not kill yeast. Best combined with an antifungal.
- Coal tar — helpful, particularly where psoriasis overlaps. Has a strong smell.
How to use a medicated shampoo properly
This is where most treatment fails, and it costs nothing to fix.
- Apply to the scalp, not the hair. The scalp is where the problem is.
- Leave it on for five minutes before rinsing. Rinsing immediately does almost nothing — contact time is what kills the yeast.
- Use it two to three times a week during a flare, then once weekly for maintenance.
- Rotate between two different actives — for example ketoconazole and zinc pyrithione, alternating monthly. This reduces the loss of response people notice after a few months.
- You can use an ordinary conditioner on the hair ends afterwards.
When shampoo is not enough
For stubborn or severe cases a dermatologist can add: a topical steroid lotion or solution for short courses to settle inflammation and itch, topical calcineurin inhibitors for facial involvement, or oral antifungals such as itraconazole or fluconazole for extensive disease. Steroid lotions are effective but for short, defined periods — long-term unsupervised use on the scalp and face causes its own problems.
Controlling the relapse
The most important message in this article: dandruff is a chronic, relapsing condition. It is controlled, not cured. Treating a flare and stopping altogether guarantees the flare returns within weeks, which is why people believe nothing works.
What reduces relapse:
- Weekly maintenance shampoo, even when the scalp looks clear. This is the single most effective step.
- Reduce scalp oiling. If you cannot give it up entirely, oil for an hour before washing rather than leaving it overnight.
- Wash more often in humid weather. Sweat and sebum accumulation drive flares — and here that means monsoon and summer both.
- Do not scratch. Scratching worsens inflammation and can cause secondary bacterial infection and temporary hair fall.
- Manage stress and sleep. Flares genuinely track with both.
- Wash pillowcases regularly and avoid sharing combs.
Does dandruff cause hair loss?
Indirectly, yes — and this worries people more than the flakes. Persistent scalp inflammation and scratching can cause increased shedding, and severe untreated seborrhoeic dermatitis is associated with hair thinning. The good news is that this hair loss is usually reversible once the inflammation is controlled. It does not cause permanent pattern baldness. If your hair is thinning and your scalp is itchy and flaky, treating the scalp is part of the hair treatment.
See a doctor if
- Six to eight weeks of correct medicated shampoo use has not helped
- The scalp is weeping, crusted, tender or has a bad smell — suggests bacterial infection
- There are bald patches or visible hair breakage
- Thick silvery plaques extend beyond the hairline, or you have nail pitting — this may be psoriasis
- A baby has thick yellow scale (cradle cap) that is spreading or infected
Frequently asked questions
No. Dandruff is an inflammatory reaction to Malassezia, a yeast that feeds on scalp oil. That is why applying more oil usually makes it worse, and why antifungal shampoos work while moisturising treatments do not.
Look at the active ingredient rather than the brand. Ketoconazole 2% is the most effective, with zinc pyrithione, selenium sulphide and ciclopirox as good alternatives. Rotating between two different actives helps maintain the response.
Five minutes on the scalp before rinsing. Contact time is what kills the yeast — rinsing immediately is the single most common reason medicated shampoos appear not to work.
It generally makes it worse, because Malassezia feeds on oil. If you want to continue oiling for other reasons, apply it about an hour before washing rather than leaving it overnight.
Indirectly. Persistent inflammation and scratching increase shedding, and severe untreated seborrhoeic dermatitis is linked to thinning. This is usually reversible once the scalp is treated, and it does not cause permanent pattern baldness.
Because it is a chronic relapsing condition that is controlled rather than cured. Stopping treatment entirely once the scalp clears allows the yeast to build up again. Weekly maintenance shampoo is the most effective way to prevent flares.
