What it actually is
A yeast of the Malassezia genus lives on everyone’s skin. In most people it causes no trouble. In some, the immune system reacts to it, particularly in areas rich in sebaceous glands — scalp, brows, glabella, nasal folds, behind the ears, mid-chest. The result is inflammation with greasy scale.
This explains two things. First: it is not contagious, because the yeast is already on everyone’s skin. Second: it is not cured, because you cannot permanently eliminate something that is part of the normal flora. It is kept in check.
And it explains the most expensive mistake: washing more and scrubbing harder makes it worse, because it irritates already inflamed skin. Nor is it dry skin: simply moisturising resolves nothing.
What it gets confused with
The right diagnosis matters because the treatments differ:
- Scalp psoriasis: the scale is dry and silvery, the plaque is thicker, and there are usually lesions on elbows, knees or nails. See psoriasis.
- Rosacea: it also reddens the face, but with sudden flushing and visible capillaries, and no greasy scale. The two frequently coexist. See rosacea.
- Atopic dermatitis: the scale is dry and itch dominates the picture. See atopic dermatitis.
- Tinea: a genuine fungal infection, which needs different treatment and is ruled out in consultation.
How it is controlled
Prescribed and supervised in the dermatology consultation. No drug names or regimens here:
- Topical antifungal and anti-inflammatory therapy under prescription, adjusted to the site: the scalp is not treated the same way as the face.
- Medicated shampoos, with adequate contact time — the commonest error is applying and rinsing immediately: they must be left to work.
- Long-term maintenance. This is the part that decides the outcome. Almost everyone treats the flare, improves, stops, and relapses within weeks. Spaced maintenance therapy is what breaks that cycle.
- Gentleness: less friction, less very hot water, fewer irritating products.
The triggers
It worsens with stress, with cold and dry weather (winter worsening is classic), with poor sleep and with alcohol. It usually improves with moderate sun.
One clinically relevant point: seborrheic dermatitis that is sudden, extensive or unusually stubborn in a young adult warrants a broader medical assessment, because it can be associated with other conditions. It is not cause for alarm; it is cause for someone to look.
Who treats it here
Diagnosis and treatment of seborrheic dermatitis belong to the clinic’s dermatology consultation — the same one with which Dr. Francisco Arellano Ocampo founded the house in 1971. Dr. Arístides Arellano is a plastic surgeon, not a dermatologist: his contribution here is surgical and reconstructive, and the disease itself is managed in the consultation. Book at dermatology consultation.
Dr. Arístides Arellano is a plastic surgeon holding a specialty licence: he practises under a Mexican medical licence (D.G.P. 1125959) and a specialty licence in Plastic & Reconstructive Surgery (0002008), both issued by the Directorate General of Professions (DGP), which reissued his certificate of professional standing in 2025. His career began before Mexico’s present-day specialty-board system existed: he belongs to the founding generation of plastic surgery in Puebla, the second generation of a surgical tradition started in 1971 by Dr. Francisco Arellano Ocampo. Trust is verified, not promised: both licences are public and anyone can look them up in the DGP’s National Registry of Professionals.
Risks and expectations
Every medical treatment —topicals, peels and energy-based devices included— carries risk and requires a prior assessment. In darker skin (Fitzpatrick IV–VI, the most common phototypes in Mexico) a poorly indicated procedure can darken the patch instead of lightening it. Results may vary according to each patient, their phototype and their individual triggers.
Trust is verified, not promised. All 210 scanned documents —degree, licences, diplomas, publications and certificates, from 1977 to 2025— are open in Dr. Arístides Arellano’s credential archive, alongside an explanation of the difference between a specialty licence and a board certification.
Control plan
- DiagnosisDermatology consultation. Distinguished from psoriasis, rosacea, atopy and tinea.
- FlareTopical therapy under prescription, adjusted to the site.
- ScalpMedicated shampoo with adequate contact time. Do not rinse immediately.
- MaintenanceThe part that decides the outcome. Spaced, but sustained.
- TriggersStress, cold, dry weather, poor sleep, alcohol.
- ExpectationKept in check. Not cured: the yeast is normal flora.
Frequently asked questions
Can seborrheic dermatitis be cured?
No, it is controlled. The Malassezia yeast that triggers the inflammation is part of everyone’s normal skin flora and cannot be permanently eliminated. With treatment and, above all, long-term maintenance, it is kept in check and calm periods are long. Stopping maintenance once it improves is the number-one cause of relapse.
Is it contagious?
No. The yeast involved is already on everyone’s skin; what varies is the immune system’s reaction to it. It is not passed on by contact, or by sharing a towel, comb or pillow.
Is it the same as dandruff?
Ordinary dandruff is the mildest form of the same process, limited to the scalp. Seborrheic dermatitis is the full picture: redness with greasy scale that can also affect brows, glabella, the sides of the nose, behind the ears and mid-chest. If supermarket shampoo does not fix it, it is no longer just dandruff.
Should I wash my hair more?
Washing more and scrubbing harder usually makes it worse, because it irritates already inflamed skin. What matters is not frequency but the product and the contact time: a medicated shampoo must be left on for the prescribed minutes, not applied and rinsed immediately — the commonest error.
Is it dry skin? Do I just moisturise?
It is not dry skin, though the scale looks like it: it is inflammation with greasy scale. Moisturising without treating the inflammation and the yeast resolves nothing. The correct treatment is topical, antifungal and anti-inflammatory, prescribed in the dermatology consultation according to the site involved.
Every case is different. Discuss yours in a personal consultation.
Book a consultation on WhatsAppEvery figure published on this site is approximate and is not a quote. Any procedure or treatment first requires a private assessment consultation with Dr. Arístides Arellano —$800 MXN, charged separately— and it is at that consultation that the definitive cost of your case is determined.
Educational content; it does not replace a medical consultation. Results may vary from person to person.