Seborrhoeic Dermatitis

Introduction

Seborrhoeic dermatitis is a form of scaly and flaky eczema (dermatitis), which mainly occurs on the face, scalp and trunk. It typically affects areas with a high number of sebaceous glands.

Seborrhoeic dermatitis is a common, benign condition which affects 1-5% of the world’s population.¹

Aetiology

The exact aetiology of seborrhoeic dermatitis is unknown. However, it is thought to be an inflammatory reaction to the yeast, Malassezia spp.

In young infants, seborrhoeic dermatitis can manifest as ‘cradle cap’ which is a widespread greasy scale on the scalp.

Interestingly, dandruff (pityriasis capitis) is thought to be a non-inflammatory form of seborrhoeic dermatitis.

Risk factors

Risk factors for seborrheic dermatitis include:¹

• Psoriasis
• Immunosuppression: patients with HIV, organ transplant recipients
• Medications can trigger the development of seborrhoeic dermatitis (e.g. chlorpromazine, haloperidol, lithium, interferon alpha, methyldopa, buspirone and griseofulvin)
• Neurological conditions such as Parkinson’s disease and epilepsy
• Stress

Clinical features

History

Typical symptoms of seborrhoeic dermatitis include:

• Pruritus
• Blepharitis (if affecting the eyelids): patients may complain of gritty-feeling, sore and swollen eyelids

Other important areas to cover in the history include:

• Past medical history: risk factors for developing seborrhoeic dermatitis

Clinical examination

The typical appearance of seborrhoeic dermatitis is erythematous, greasy scaly patches usually between the eyebrows, around the creases of the nose, behind the ears and on the scalp (Figure 1).

In extensive cases, the patches can also occur in the groin and armpit folds.

Differential diagnoses

Seborrhoeic dermatitis can appear similar to the following dermatological conditions, it is especially important to consider alternative diagnoses if the rash is widespread:

• Rosacea
• Psoriasis
• Atopic dermatitis

Investigations

Diagnosis is typically made following clinical examination and investigations are not usually required

If the rash is particularly widespread, HIV testing should be considered.

Management

Seborrhoeic dermatitis usually responds well to topical treatment, depending on where the patches manifest will change the choice of treatment. Patients should be educated that this is a chronic condition and will likely need repeat treatment in the future.

Most cases of seborrheic dermatitis can be managed easily in primary care. However, if it is particularly widespread or severe, a referral should be made to a dermatologist.    

Scalp

If thick scales are present, olive oil, salicylic acid or coal tar will need to be used first to help lift the keratotic scales. Following this, ketoconazole shampoo should be used twice weekly for one month.²

Face

For seborrhoeic dermatitis affecting the face, ketoconazole cream daily for up to 4 weeks can be used. Add in 1% hydrocortisone cream if particularly inflamed for a maximum of 2 weeks.³

Other treatment options include topical calcineurin inhibitors (pimecrolimus cream/tacrolimus ointment). This use is off licence.¹

Complications

Seborrhoeic dermatitis is a benign condition. However, secondary bacterial infection of the affected body areas can occur.

Key points

• Seborrhoeic dermatitis is a common chronic condition characterised by erythematous, greasy scaly patches mainly on the face and scalp.
• Risk factors include immunosuppression, stress, psoriasis, neurological conditions and certain medications. 
• Consider alternative diagnoses in patients with a widespread rash.
• Most flares resolve easily with topical treatments including ketoconazole and hydrocortisone cream.
• Secondary bacterial infection of the affected areas can occur. 

Reviewer

Dr Thomas King

Consultant Dermatologist

Editor

Dr Chris Jefferies

References    

1. Patient Professional. Seborrhoeic Dermatitis. Last updated March 2022. Available from: [LINK]
2. NICE CKS. Seborrhoeic Dermatitis – Management Scalp and Beard. Last updated 2022. Available from: [LINK]
3. NICE CKS. Seborrhoeic Dermatitis – Management Face and Body. Last updated 2022. Available from: [LINK]

Image references

•  Figure 1. Amras666. Seborrhoeic dermatitis. License: [CC BY-SA]