Original author: Dr Amy Stanway, 2004. Revised and fully updated by Dr Douglas Maslin, Specialist Registrar in Dermatology and Clinical Pharmacology, Addenbrooke’s Hospital, Cambridge, UK. DermNet Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, New Zealand. Feb 2018; Minor update 2023.
This update was made possible with independent financial support from LEO Pharma A/S.
Psoriasis is a common, chronic, immune-mediated skin disease with characteristic red, scalyplaques caused by the excessive proliferation of skin cells.
Despite recent advances in our understanding of the mechanism of how psoriasis develops, psoriasis may be difficult to treat; there is currently no cure and no single treatment works for everyone.
Several treatments may need to be tried before the most suitable regime is established, and different treatments may need to be used concurrently, or in rotation, for best effect or to minimise side-effects.
Treatment of adults with psoriasis includes:
General measures
Topical preparations
Ultraviolet therapy
Systemic non-biological therapy
Systemic biological therapy.
Treatment choice in psoriasis depends on a number of factors. For example:
Disease pattern
Disease severity: body surface area (BSA) affected and Psoriasis Area and Severity Index (PASI) score
Health conditions associated with psoriasis include psoriatic arthritis, sleep disturbance, and depression. Treatment for these may help skin disease.
Due to the association between psoriasis and metabolic syndrome, weight loss, smokingcessation, moderation of alcohol intake, and blood pressure control may also lead to improvements in skin disease [1,2].
Sun exposure
Sun exposure (heliotherapy) may help to clear psoriasis; in many people, psoriasis improves dramatically during summer months or on sunny holidays.
Short-term side-effects include the development of psoriasis in areas of sunburn, (due to the Koebner phenomenon).
Antiseptics are not necessary and may cause skin irritation.
Balneotherapy (the treatment of disease by bathing in mineral springs) is a popular form of complementary therapy in certain demographic areas [3], although there is little or no strong evidence of benefit.
Probiotics
One avenue of current research is looking at the skin and gut microbiome (the bacteria living on and in the human body) and whether the alteration of this microbiome may be effective in the treatment of psoriasis [4,5]. To date, probiotics have not been found to help psoriasis.
Occlusive dressings
Relatively small, localised patches of psoriasis may improve with occlusion (eg, using waterproof adhesive dressings).
Topical preparations for psoriasis
Emollients
The regular use of emollients and moisturisers softens psoriasis and adds moisture to the skin. This improves dryness, scaling, and irritation.
There are a diverse range of options of lotions (ie, for scalp psoriasis), creams, and ointments (ie, for dry, thick, scaly areas).
Be aware of the flammability of emollients and the risk of slipping in the bath after applying these agents to the feet. Emollients can rarely irritate the skin; this is less likely with ointments than with lotions and creams.
Keratolytic agents
Keratolytic agents can be useful to reduce the thick scale. They may contain urea (5–40%), salicylic acid (0.5–10%) or propylene glycol (for example, propylene glycol 20% in aqueous cream).
Topical steroids are available in various strengths and formulations (including steroid impregnated tape). Topical steroids are also used in combination with other agents, such as with:
The selection of a suitable product depends on the site and type of psoriasis.
Weak topical steroids are used on sensitive sites (ie, the face, flexures, and genital areas).
In contrast, palmoplantar psoriasis requires a very potent topical steroid due to the thicker skin on the hands and feet.
Potent steroids are often more effective than mild topical steroids, but they have a higher risk of side-effects. They should be used with caution in large areas and for limited periods. They may cause:
Topical steroids are useful for the itch of psoriasis, and work well for the inflammation initially. However with continued use tachyphylaxis develops, and the anti-inflammatory effect wears off.
Topical steroids can be used under medical supervision in pregnancy and, alongside emollients, are generally the first-line treatment of psoriasis in pregnancy.
Dithranol (also called anthralian or anthralin) is occasionally recommended as a treatment for chronic plaque psoriasis. It can be very effective but dithranol treatment has a number of practical drawbacks and so is less frequently prescribed.
The method of application is complex; it is usually given as ‘short contact' therapy.
Dithranol is normally applied once a day.
It is applied directly to psoriasis (ie, avoiding normal skin) and then washed off after 10–60 minutes.
The strength of dithranol is gradually increased every few days until it is effective, or until skin irritation occurs.
Dithranol permanently stains fabrics and temporarily stains the skin.
The most common side-effect is skin pain and local irritation. It is not currently available in New Zealand (July 2018).
Roflumilast
Topical roflumilast 0.3% cream (Zorvye™) was approved by the FDA in 2022 for the treatment of plaque psoriasis in patients aged 12 years and older. This is the first topical PDE4 inhibitor approved for use in psoriasis.
Tapinarof
Tapinarof 1% cream (VTAMA®) is a once-daily, novel, topical agent for patients with mild, moderate, and severe plaque psoriasis, first approved by the US Food and Drug Administration (FDA) in May 2022.
Other
Off-label use of the phosphodiesterase-4 topical inhibitor crisaborole has been shown to be effective for flexural and facial psoriasis.
Ultraviolet treatment for psoriasis
Phototherapy is the use of UV radiation to treat skin disorders, and this can be very effective in the treatment of psoriasis. It is generally reserved for cases where topical therapy has been ineffective or too much of the skin surface is involved to treat psoriasis effectively with topical agents. It is administered in cabinets at specialised centres, and a treatment course for psoriasis will usually consist of 2–3 treatments per week for 20–30 treatments.
It is generally felt to be safe and well-tolerated. About two-thirds of patients with plaque psoriasis experience a 75% improvement in PASI score (PASI 75) compared to baseline with this treatment [9].
UVB is felt to be safe in pregnancy. Note that UVB degrades folic acid and regular supplementation in pregnancy is needed [10,11].
A retrospective study found no increased risk of skin cancer with the combination therapy of narrowband UVB and methotrexate, when compared to the use of narrowband UVB therapy alone.
Psoralen and ultraviolet A
Psoralens plus long wave ultraviolet A (UVA) radiation, (known as photochemotherapy), can be applied to the whole body by giving an oral psoralen in tablet form 2 hours prior to treatment.
Treatment can be localised to the hands and/or feet by using psoralen bath soaks or topical psoralens prior to treatment.
Photosensitivity persists for some hours following oral psoralen treatment; therefore, patients are advised to avoid sun exposure, including wearing wrap-around sunglasses on the day of treatment.
PUVA is more likely than narrowband UVB treatment to cause skin cancer, especially squamous cell carcinoma and is usually limited to a maximum of 100 to 200-lifetime treatments.
Psoralens and therefore PUVA is not recommended during pregnancy or breastfeeding.
Systemic non-biological medication for psoriasis
Systemic (oral or injectable) medication may be required to treat psoriasis when:
Dose varies from 10 mg three times weekly to 50 mg daily.
Acitretin is often combined with phototherapy
20–40% of patients treated with acitretin at full dose achieve PASI 75 by Week 16 [14].
Regular blood tests should monitor the patient's liver function and blood fats.
Pregnancy must be strictly avoided while on acitretin and for at least 3 years afterwards because it is associated with serious birth deformities (the US and TGA pregnancy category X). Acitretin is therefore rarely given to women of childbearing age.
The risk does not apply to men, as acitretin does not affect sperm.
Dose-related side-effects of acitretin include dry lips, peeling palms and soles, thinning hair, tiredness, and muscle pains.
The dose is usually gradually increased to achieve an effect. PASI 75 is achieved 38% of patients at Week 16.
Blood tests should monitor the patient's kidney, liver, and white blood cells.
Side-effects include nausea, diarrhoea, stomach cramps, flushing, and headaches. A rare but serious side-effect is a nervous system viral infection (progressive multifocal leukoencephalopathy).
Fumaric acid esters are not to be used during pregnancy due to fetal harm.
Other non-biological medications
Other non-biological oral medications used less commonly for psoriasis include:
Biological therapies or biologics are monoclonalantibodies or recombinant proteins targeted at specific components of the immune system. They are often very effective treatments for psoriasis.
The risk of serious side-effects relates to their effect on immunity.
They are very expensive and the prescription is tightly regulated.
They are used for moderate-to-severe psoriasis that has failed on topical and systemic treatment options or when these are contraindicated.
Each available biologic has individual risks and benefits. Novel biological therapies are under development. Currently available biologics and those under development include:
The biologicals for psoriasis are given by subcutaneous injection, with the exception of infliximab, which is administered intravenously. Infliximab is a chimera of mouse and human protein and can result in infusion reactions and antibody formation.
Biosimilars are drugs that are nearly identical to an original biological medication that has come off patent [15] and are available at a reduced cost. Biosimilars are available for infliximab and etanercept and others are under development (July 2018).
Oral drugs under development include small molecule compounds targeting signalling pathways, such as JAK inhibitors and PDE inhibitors. As they are low molecular weight, topical formulations are being investigated.
Effect of adalimumab on psoriasis
Before treatment
After treatment
References
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