Psoriasis is a chronic, relapsing, scaly skin condition which is usually easy to diagnose but can be difficult to manage. While most mild to moderate cases can be managed in general practice, patients with more resistant, severe or extensive psoriasis may have to be referred to a dermatologist for ultraviolet light treatment or systemic therapy. 

Not all cases of psoriasis require treatment. Many men and some women with localised psoriasis on their elbows, knees and/or scalp can learn to live with their condition by covering it up with appropriate clothing. However, others can be very self-conscious even with limited disease, which may interfere with their work, social life, sex life or hobbies. For some, going to the swimming pool, a changing room or  the beach can be a nightmare. Fortunately, most patients with mild to moderate disease can now be managed safely and effectively in general practice.

It is important to reassure patients that psoriasis is not contagious, infectious or cancerous. Certain prescription medication can aggravate psoriasis and these may have to be stopped or substituted if the psoriasis proves difficult to control. Alcohol in excess is also a common cause of psoriasis flare-ups. Patients should be encouraged to avoid alcohol or keep it to a minimum (ie. less than 10 units a week). Patients with psoriasis have a high incidence of obesity, hypertension, hyperlipidaemia, diabetes, heart disease and depression, and so should be screened for these conditions.

The first step in the management of psoriasis is to moisturise the plaques liberally with a safe, greasy moisturiser after baths or showers, such as emulsifying ointment, Epaderm or paraffin gel. This will reduce the silvery scale and make the psoriasis look and feel better. It can also help other more specific psoriasis treatments penetrate better. A tar-based shampoo will help lift off the scales on the scalp and if there is co-existing dandruff, a good anti-dandruff shampoo such as Nizoral or Stieprox should be used two or three times a week. Very thick scalp scales can be removed with a tar and salicylic acid ointment such as Cocois.

The first-line treatment for adults with chronic, stable, plaque psoriasis on the body is usually Dovobet, which is a combination of calcipotriol (a vitamin D analogue) and betamethasone, (a potent steroid, the same as Betnovate). Dovobet comes in a gel or ointment base. The gel preparation is more cosmetically acceptable and can be used on the scalp. The ointment preparation is more effective although more greasy to use. 

The advantage of Dovobet is that it is relatively quick at improving the psoriasis plaques and can be used in convenient, once a day applications, which usually do not burn, sting or stain the skin. The disadvantages are that it is expensive and does not work on all patients with psoriasis. Dovobet is not licensed for people under 18 years of age. 

The maximum dose in adults is 15g a day, or 100g a week for acute management of psoriasis in the first month of treatment and it should not be used on more than 30% of body surface area. It should be applied once daily for at least one month until the silvery scaly plaques fade out to a red, macular rash. At this stage, Dovobet can be reduced to a twice-weekly application, and Dovonex cream (calcipotriol on its own) can be used daily for the other five days of the week for the second month. 

Usually, in the third month, the twice-weekly Dovobet can be stopped and the patient managed with Dovonex Cream on its own, until the psoriasis is fully cleared or reduced to an acceptable level. More recently, Dovobet has obtained a licence for long-term use. Some doctors reduce Dovobet to alternate days in the second month and eventually to once or twice a week till cleared. However, I prefer to wean patients off Dovobet onto Dovonex after one to three months and save Dovobet for relapses of psoriasis. 

Using Dovobet long-term, (greater than three months) may cause skin atrophy (which looks very like partially treated psoriasis) and possibly systemic absorption with adrenal suppression. A rebound flare of psoriasis can occur if Dovobet is stopped suddenly. Dovobet should never be applied to the face or flexures. 

Dovobet gel is also useful for scalp psoriasis, where it should be rubbed into the plaques overnight. It can be removed in the morning by applying a shampoo to the gel in the dry scalp for a few minutes to soften the gel before wetting the hair and lathering up the shampoo. The gel will then easily wash out once the hair is rinsed. Daily hair washing can be tedious, so I usually recommend applying Dovobet gel to the scalp daily for the first week and then three times a week until the psoriasis has cleared (this usually takes one to two months).

These complicated treatment regimes for applying Dovobet gel or ointment to the body and scalp are difficult to explain to a patient during the course of a routine consultation. Written instructions are essential and monthly follow-up for the first few months is useful to encourage compliance and to monitor progress. A nurse trained in the use of these products is very useful in helping patients manage their psoriasis.

Patients who have only very small plaques of psoriasis in localised areas of the body may not want the expense of buying a large tube of Dovobet which they will not use. In these circumstances, it can be cost-saving to prescribe Dovonex cream in the morning and a potent topical steroid (eg. Betnovate ointment) at night to all the plaques on the body for one month. 

A patient can be weaned off the steroid ointment by using it twice a week in the second month and stopping it altogether in the third month of treatment while continuing with Dovonex cream daily until the psoriasis is cleared or well controlled. Dovonex cream can be used with a moderately potent topical steroid (eg. Eumovate Ointment) in children from 6 to 12 years old in a similar fashion. 

While Dovobet is clean and relatively simple to use, it only works in 60-70% of patients with chronic stable plaque psoriasis. In these patients, Dithranol is extremely effective, although more difficult and more time-consuming to use. The ‘short contact treatment’ using a preparation called Dithrocream is the most convenient way to use dithranol for home treatment. Dithrocream comes in five different strengths, from 0.1% up to 2%. Patients should be instructed to start with the weakest strength and to apply it to the plaques on the body and scalp (not for the face or flexures) for 30 minutes daily for one week. 

It can be washed off in the shower, but patients should be warned that it will stain everything, including clothing, towels and the skin. Each week, the strength should be increased until the psoriasis clears. If the skin gets red or sore (usually at the higher strengths) the treatment should be stopped for a few days until the soreness settles. Then the treatment can be restarted but at the next strength down. 

The best way to tell when the psoriasis is cleared and when to stop Dithrocream is to get the patient to rub their hand over the affected area. If it is smooth, like the surrounding skin, although stained with Dithranol, they can stop the treatment. If it is rough, they should continue short contact treatment with Dithrocream until smooth. 

Once Dithrocream is stopped, the staining will fade spontaneously over the following few weeks, or this can be accelerated by applying a tar-based ointment such as Coal Tar and Urea, rubbing it downwards daily to the stained area. However, tar ointments are smelly, sticky and not usually popular with the patients. 

When prescribing dithranol, written instructions are essential for the patient and a trained nurse can ensure good compliance and good success. When Dithrocream is used properly, it can clear up to 80-90% of adults and children with mild to moderate, stable plaque psoriasis in approximately six weeks. It can also lead to longer remissions than with other treatments, such as Dovobet and Dovonex. Although more time-consuming and messy to apply and wash off, Dithrocream can clear psoriasis faster than Dovobet/Dovonex. 

For more troublesome chronic plaque psoriasis, combining treatments may be helpful. For example, dithranol and tar is a good combination, or Dovobet and dithranol can be used simultaneously. However, if the patient is bad enough for these types of combinations, the GP should consider referring the patient for ultraviolet light therapy or systemic treatments, such as methotrexate, fumaric acid or the new biological therapies. 

The sun can help psoriasis in most patients and will make topical treatment such as Dovobet/Dovonex or dithranol more effective. I wonder if the HSE would consider paying for a cheap two-week package tour to the sun for psoriasis patients, which might work out cheaper than six weeks photo therapy! 

Psoriasis on the face and flexures is usually less thick and scaly than on other parts of the body and will often respond to 1% hydrocortisone ointment. If there are any signs of co-existing seborrhoeic dermatitis, then 1% hydrocortisone combined with imidazole anti-fungal (eg. Daktacort, Canesten HC) should help.