seborrheic dermatitis

23 Jul

Seborrheic dermatitis is an inflammatory condition that has been speculated to be caused by Malassezia yeasts. This impacts the scalp, hairline, and face that produces itchiness, dandruff and greasing on the skin. This is a harmless condition that can be treated easily.

- 3-5% globally is the prevalence rate of seborrheic dermatitis
- In the US, 300 million dollars are spent yearly on over-the-counter treatment for dandruff [1]
- Affects up to 5 in every 100 adults according to Bupa UK
- 50% of adults have dandruff (a mild form of seborrhoeic dermatitis)
- Men are more likely than women to get the condition [2]
- Caused by a combination of genetic and environmental factors
- The Malassezia yeast overgrows and the immune system overreacts to the yeast
- Triggers include:
  - Stress
  - Hormonal changes
  - Harsh chemicals/soaps/detergents
  - Environmental changes (eg. cold, dry)
  - Medications such as lithium
- Underlying conditions such as HIV and Parkinson’s [3]
Medical Students
- SD is a common papulosquamous skin condition with clinical similarities to psoriasis.
- Characterised by:
  - Excessive oiliness (seborrhea)
  - Dandruff
  - Yellowish, dry, or greasy scales
  - Erythematous, follicular, scaly papules that may coalesce into plaques or circinate patches
- Aetiology is multifactorial:
  - Involves both intrinsic and environmental factors
  - Genetic predisposition affecting immune response and epidermal differentiation
  - Often linked to immune dysfunction (e.g. common in HIV/AIDS)
- Malassezia yeast:
  - Not the primary cause, but may contribute by interacting with a compromised immune system
  - Produces lipases → release arachidonic acid → induces inflammation
- Associated immune/inflammatory factors:
  - Increased natural killer cells
  - Elevated inflammatory cytokines
  - Activation of the alternate complement pathway
  - Impaired skin barrier function (genetic basis)
- Aggravating factors:
  - Changes in humidity
  - Scratching
  - Emotional stress
  - Diet
  - Certain medications
  - Androgen excess
Patients
- SD is a common skin condition that shares features with psoriasis.
- Signs and symptoms may include:
  - Oily skin and dandruff
  - Yellow, dry, or greasy flakes
  - Redness and scaly patches, sometimes in circles or large areas
- Common in:
  - Infants (typically 2–12 weeks old)
  - Adults in midlife or older
  - Often recurs over time
- Cause is not fully known, but involves:
  - A mix of genetic, immune, and environmental factors
  - Issues with the skin’s natural barrier and how the body handles inflammation
- A natural skin yeast called Malassezia can worsen the condition by causing irritation, but it’s not the main cause.
- Things that can make SD worse:
  - Weather changes (like humidity)
  - Scratching
  - Stress
  - Diet
  - Some medications
  - Hormone imbalances (especially androgens) [4]
- Male
- Increased sebacous gland activity
- Weakened immune system such as HIV and lymphoma
- Neurological diseases such as stroke, and parkinsons disease
- Drug usage such as;
- Lithium
- Immune suppressants
- Dopamine antagonists
- Environmental changes with low humidity and cold temperatures [5]
- Dry flakey skin
- Greasy scaling on the scalp
- Redness and scaling on regions of the skin such as the back of the ear, eyebrows and along the hairline
- Thick, stuck-on scaly plaques on the scalp [6]
- Clinical assessment of the appearance and a history of symptoms
- Skin biopsy may be needed to investigate the skin under the microscope to rule out infections [7]
- Psoriasis
- Atopic dermatitis/ allergic contact dermatitis- inflammation of the skin caused by allergens
- Tinea capitis- ringworm
- Rosacea- redness of the skin
- Systemic lupus erythematous- butterfly rash on the face [8]
Medical Students
- Chronic condition – maintenance treatment often needed.
- Avoid irritants – recommend non-greasy emollient soap substitutes instead of soap or shaving cream.
- Stress can trigger or worsen flares.
- Scalp & Beard:
  - First-line: ketoconazole shampoo (leave on for 5 mins).
  - Pre-treatment scale removal:
  - Mild: warm olive/mineral oil.
  - Thick: keratolytic (e.g. salicylic acid + coconut oil).
  - Alternatives: zinc pyrithione, coal tar, salicylic acid shampoos.
  - Severe itching: short course of topical corticosteroids (e.g. betamethasone valerate, mometasone furoate).
  - Do not use corticosteroids on beard area due to facial skin sensitivity.
- Face & Body:
  - First-line: ketoconazole cream or another imidazole (e.g. clotrimazole, miconazole) for ≥4 weeks.
  - For maintenance: reduce frequency once controlled.
  - Flares: short-term mild steroids (e.g. hydrocortisone).
- Paediatrics:
  - Use imidazole creams.
  - Mild steroids (e.g. hydrocortisone) only for flares – limit to 1 week.
  - Adolescents: ketoconazole shampoo as body wash (not under 12s).
- Eyelids: daily hygiene with baby shampoo-moistened cotton buds.
- Review/Referral:
  - No routine follow-up unless poor response, worsening symptoms, or infection.
  - Refer for diagnostic uncertainty, severe/widespread disease, or unresponsive eyelid involvement.
Patients
- This is a long-term (chronic) skin condition and may come back over time.
- Avoid soaps or shaving creams that irritate your skin. Use gentle, non-greasy soap alternatives instead.
- Stress can make it worse – try to manage stress if possible.
Scalp and Beard:
- Use anti-fungal shampoos like ketoconazole (available from pharmacies).
- Apply oil (like olive or baby oil) to soften crusts before shampooing.
- Leave shampoo on for 5 minutes before rinsing.
- If itching is very bad, your doctor might suggest a short course of a scalp steroid lotion.
- Do not use steroids on your beard area – the skin there is more sensitive.
Face and Body:
- Use anti-fungal creams (e.g. ketoconazole, clotrimazole) daily for at least 4 weeks.
- Once better, you might use the cream less often to stop it coming back.
- During flare-ups, your doctor may suggest a mild steroid cream like hydrocortisone for a short time.
For Children and Teens:
- Use anti-fungal creams as above.
- Only use steroid creams for one week, and only when needed.
- Teens may also use anti-fungal shampoo as a body wash (not suitable for kids under 12).
If your eyelids are affected, gently clean them daily using a cotton bud with diluted baby shampoo.
When to see a doctor again:
- If treatment isn’t working
- If things get worse
- If there are signs of infection (redness, pain, pus)
You may be referred to a specialist (skin doctor or children’s doctor) if the diagnosis is unclear or the condition is hard to manage. [9]
- Areas exposed to moisture and eyelids are prone to secondary infections
- In infants, the diaper area commonly growth the fungal infection
- Self esteem- self worth complications from appearance
- Skin thinning and dilated blood vessels [10,11]
- You should remove the dry flakes before shampooing the hair
- Dandruff is worse in the summer
- All flakes are a sign of dandruff
- Seborrheic dermatitis is the cause of all dandruff [12]
- What causes seborrheic dermatitis?
- How can you diagnose the cause of my dandruff?
- How long will treatment take to be effective?
- What lifestyle changes can I make to manage my symptoms?
- If I take other medications, will that change my treatment plan for my seborrheic dermatitis?
- Bupa UK
- National Eczema Society
- American Academy of Dermatology
[1] https://emedicine.medscape.com/article/1108312-overview#a9
[2] https://www.bupa.co.uk/health-information/healthy-skin/seborrhoeic-dermatitis#:~:text=Seborrhoeic%20dermatitis%20affects%20up%20to,mild%20form%20of%20seborrhoeic%20dermatitis.
[3] https://nationaleczema.org/eczema/types-of-eczema/seborrheic-dermatitis
[4] https://www.sciencedirect.com/topics/medicine-and-dentistry/seborrheic-dermatitis
[5] https://www.ncbi.nlm.nih.gov/books/NBK551707/
[6] https://www.msdmanuals.com/en-gb/professional/dermatologic-disorders/dermatitis/seborrheic-dermatitis?query=seborrheic%20dermatitis
[7] https://www.aad.org/public/diseases/a-z/seborrheic-dermatitis-treatment
[8] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4852869
[9] https://cks.nice.org.uk/topics/seborrhoeic-dermatitis/management/
[10]https://www.ncbi.nlm.nih.gov/books/NBK551707/#:~:text=Seborrheic%20dermatitis%20usually%20takes%20a,to%20overgrowth%20with%20Candida%20spp
[11] https://dermnetnz.org/topics/seborrhoeic-dermatitis
[12] https://www.self.com/story/dandruff-myths