Seborrheic Dermatitis
Skin condition causing scaly patches and red skin mainly on the scalp.
TL;DR
Seborrheic dermatitis is an inflammatory overreaction to a normal skin yeast — not poor hygiene and not curable, but very controllable. Antifungal shampoos (ketoconazole, zinc pyrithione, selenium sulfide) have the strongest evidence and are first-line. Stress and cold dry weather reliably flare it; neurological conditions like Parkinson's are associated with severe forms. Sudden severe onset in an adult warrants a health review, including HIV risk consideration.
Overview
Flaky, greasy, sometimes reddened patches on the scalp, eyebrows, sides of the nose, and chest — dandruff is its mildest scalp form. It is driven by an inflammatory reaction to Malassezia yeast that lives on everyone's skin, flaring with stress, cold weather, and neurological conditions.
Root Causes
Evidence synthesis: The condition reflects an inflammatory response to Malassezia yeast and its metabolites on sebum-rich skin — established by the consistent efficacy of antifungals. Ketoconazole 2% shampoo has randomised trial evidence and is guideline first-line; zinc pyrithione and selenium sulfide shampoos are evidence-supported alternatives, used 2-3 times weekly with maintenance dosing to prevent relapse. Short courses of topical steroids calm flares but are not long-term face-appropriate; topical calcineurin inhibitors have RCT support for facial disease. Flare triggers with documented association: psychological stress, cold dry weather, and neurological disease (Parkinson's strongly associated). Oral zinc, biotin, and probiotics are marketed but lack convincing trial evidence. New severe seborrheic dermatitis in an adult is a recognised clue to underlying conditions including HIV and Parkinson's — a pattern worth a medical conversation.
How It's Diagnosed
When to See a Doctor
See a clinician if patches are painful, weeping or spreading rapidly, if over-the-counter antifungal shampoos fail after 4 weeks, or if severe seborrheic dermatitis appears suddenly in adulthood.
Supplements Studied For This
Supporting Research
Zinc and dermatologic disease including seborrheic dermatitis: a systematic review
Topical antifungals for seborrhoeic dermatitis
A multicenter randomized trial of ketoconazole 2% and zinc pyrithione 1% shampoos in severe dandruff and seborrheic dermatitis
The positive benefit of Lactobacillus paracasei NCC2461 ST11 in healthy volunteers with moderate to severe dandruff
Treatment of dandruff with 5% tea tree oil shampoo
Frequently Asked Questions
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This information is for educational purposes only. Always consult a healthcare professional before starting any supplement regimen.