Corticosteroids are synthetic versions of hormones made in the body and are the most commonly prescribed medications for psoriasis. Corticosteroid creams, lotions, foams, gels, ointments and sprays are the most commonly prescribed topical agents for mild to moderate psoriasis. When applied to the skin, they reduce inflammation in the area, making them useful treatments for many forms of psoriasis. They are available in low-dose, high-dose and very-high-dose preparations.
Corticosteroids usually work quickly, and the low-dose formulations can be applied al-most anywhere on the body. For mild psoriasis limited to a few small plaques, low-dose, non-prescription strength may be all that’s needed. However, if the plaques’ crusts are thick or if they’re widespread, high-dose topical steroids may be prescribed alone or in combination with other treatments.
Potential side effects
If corticosteroids are used for an extended period over a large area, it’s possible for some of the drug to be absorbed into the body. This is called systemic absorption and it can lead to Cushing’s syndrome, cataracts, glaucoma and osteoporosis. It is important to follow any instructions your doctor gives you about using a corticosteroid cream or lotion. Side effects include:
- Fragile, thin skin, easy bruising
- Appearance of small blood vessels
- Bands of thin, red skin that turn into slivery lines (stretch marks)
- Infection of hair follicles
- Tiny red or purple spots
- Contact dermatitis (rash)
- Vulnerability to infections
- Hair growth
Topical corticosteroids can worsen rosacea, around-the-mouth rashes, athlete’s foot and similar infections. Higher-potency products are usually limited in use to only two to four weeks at one time to limit the risks of systemic absorption and other side effects. After psoriasis goes away, topical corticosteroids are gradually reduced then stopped to reduce the risk of rebound outbreaks. There is some controversy over whether people can develop a resistance to topical corticosteroids over time.
Vitamin D3 derivatives/ analogues
Vitamin D3 derivatives or analogues, such as calcipotriol, are available as creams, ointments and solutions typically for the treatment of mild to moderate psoriasis.
Vitamin D3 derivatives are corticosteroid-sparing – they enable you to use less topical corticosteroid. They are usually applied once or twice daily for about 8 weeks. When combined with topical corticosteroids, they can often work better in people with plaque psoriasis than either medication alone.
Potential side effects
Potential side effects include burning, itchiness, swelling, peeling, dryness and rash. They should not be used on the face. In patients who spread larger doses over much of their body, vitamin D3 derivatives may cause a rise in blood calcium levels, which reverses when the medication is stopped. They may also cause light sensitivity and may cause a burning sensation if applied before UVB phototherapy.
Calcitriol ointment, an active form of vitamin D, is also presently available.
Combination topical treatment
There is currently one combination topical treatment available for psoriasis patients in Canada. It contains calcipotriol (a vitamin D analogue) and betamethasone dipropionate (a corticosteroid).
Because it is a measured combination of calcipotriol and betamethasone, it has been shown to be more effective for the treatment of psoriasis and is faster acting than if the two ingredients are used alone. Even if you apply both ingredients separately but at the same time, it is hard to get the optimal proportions. Both ingredients work together to control psoriasis, and reduce the time you spend applying medication.
This ointment, gel or foam is applied once daily, directly to the psoriasis plaques. After psoriasis has improved, application can be stopped, and restarted as needed.
Potential side effects
The most common side effect is mild itching and those side effects associated with the individual ingredients listed above.
Topical retinoids may be an effective treatment for mild to moderate psoriasis. At least one topical retinoid, tazarotene, is available in Canada. When combined with topical corticosteroids, tazarotene can help prevent thinning of the skin, which is a common side effect of corticosteroids.
Combining a topical retinoid with UVB phototherapy may enhance benefits and reduce the amount of UV exposure needed for a good response.
Potential side effects
A common side effect is skin irritation in or around plaques, which may be lessened by using a moisturizer, applying the product on alternate days, short-contact (30- to 60-minute) treatments or combining this product with a topical corticosteroid.
Pregnant and nursing women cannot take topical retinoids due to the high risk of birth defects.
For a comparison of prescription topical medications see Topical Treatments Table.
Other topical agents
Over-the-counter moisturizers (emollients) leave a film on the skin’s surface, forming a barrier to retain moisture in the skin’s upper layers. These products may be soothing and may help remove the scales that form in psoriatic plaques. They may also increase the effectiveness of other topical treatments. Using a moisturizer up to three times daily is add-on therapy for psoriasis—it will not control flares on its own.
Salicylic acid can reduce scaling and soften the reddish patches (plaques) of psoria-sis. It is often combined with other topical agents. It should not be applied to more than 20% of body area. It is not recommended for use in children or people with liver or kid-ney problems. This agent can reduce the effectiveness of UVB phototherapy and it can interact with certain oral medications.
Anthralin is a yellowish cream that is mostly used as short-contact (20- to 30-minute) therapy for mild to moderate psoriasis and hard-to-treat scalp psoriasis. Its inconvenience and poor cosmetic appearance are major downfalls. It is not as effective as prescribed topical corticosteroids or vitamin D derivatives. Anthralin can stain the skin, clothing and other objects that are touched. Other side effects include skin irritation. It is no longer commercially available but can be compounded by pharmacists.
Coal tar preparations are not used as often as they once were to treat psoriasis. Today, they are available mostly as over-the-counter shampoos and gels for mild to moderate psoriasis. Formulations are not standardized, and the effectiveness of coal tar differs from one preparation to the next. For example, some studies have found that 1% lotion works better than 5% coal extract. Odour, staining and cosmetic issues can discourage many patients from using coal tar. Potential side effects include photosensitivity to UVA light, contact dermatitis and infection of hair follicles.