Question of the week 5-20: Psoriasis

Written by Jeffrey Davis on May 24, 2011, 10:31 p.m.

Psoriasis and its treatment

Psoriasis plaquePsoriasis is a common skin problem that affects the life cycle of skin cells. The cells will often build up into plaques that are characterized best their silver scale.  About 2.5% of Caucasians and 1.3% of African Americans suffer from psoriasis . The disease is chronic with periods of flareup and periods of remission (when the skin may look normal.) Remission is most common in the summer months. This may be from increased relative humidity and increased exposure to UV light. Alcohol consumption, obesity, viral infections, stress and smoking have all been shown to contribute to the development and severity of psoriasis.

There are a few other disorders that can look like psoriasis but have very different treatments. These include seborrheic dermatitis, ringworm, pityriasis rosacea and lichen planus. In most cases your doctor can make the diagnosis just by listening to your history and examining the skin but occasionally a small skin
biopsy may be taken.




The treatments for psoriasis are focused on two goals: stop the cycle that produces overgrowth of skin and plaque formation or remove the plaques from the skin.

  • Steroids: These are the most common choice for treating mild to moderate disease. They are best applied in the form of an ointment.
  • Vitamin D analogues: calcipotriene and calcitriol are also helpful and are available in an emollient or in combination with steroids.
  • Coal tar: this is probably the oldest treatment for psoriasis but honestly i’ve never prescribed it as its messy and doesn’t smell particularly good.
Light therapy
  • UV-A, UV-B are both effective for treating more severe cases although there is an increased risk of freckling, and skin cancer.
  • Pusled dye laser can obliterate small blood vessels feeding the plaques that form. Side efects include bruising
  • Combination of light therapy with certain tropicals that increase the skin’s sensitivity to light can be very effective.

Systemic therapy
  • Methotrexate can be used long term in many different forms to help control psoriasis. The dosing is usually intermittent because of the risk of hepatotoxicity
  • Retinoids used systemically (as opposed to topically) carry many risks and should be only be carried out by physicians familiar with the drugs.
  • Cyclosporin reduces your immune response which may be effective in clearing psoriasis but also makes you more vulnerable to infections.

So now to answer the question, “what is the best treatment for psoriasis”. In my practice I use the mildest treatments first alone then in combination with other mild treatments. In most cases this is a steroid by itself or mixed (compounded) with calcipotriene. If the disease does not respond, light therapy may be added. When truly resistent a more aggressive treatment is used. The goal however is to induce remission with the mildest treatment possible.