Dithranol

How it works

It reduces the excessive epidermal proliferation seen in psoriasis, with effects linked to inhibition of keratinocyte turnover and generation of reactive oxygen species in the skin.

Prescribing in practice

• Dithranol is irritant and can burn normal skin, so apply it carefully to plaques only and protect surrounding healthy skin, washing it off after the prescribed contact time.
• It stains skin, hair, clothing, bedding and surfaces, which limits acceptability and adherence.
• Avoid use on the face, flexures, genitals and acutely inflamed or unstable psoriasis.

Monitoring

Monitor clinically for plaque response and for irritation or burning of surrounding normal skin.

Counselling the patient

• Apply only to the thickened plaques, keep it off normal skin, and wash it off after the time you have been told.
• Expect staining of skin, hair, clothes and the bath; protect surfaces and use older bedding and towels.
• Stop and seek advice if the surrounding skin becomes sore or burnt.

Evidence & guidelines

Dithranol short-contact therapy is a long-established treatment for chronic plaque psoriasis supported by NICE psoriasis guidance.