Seven Different Potencies
When we talk about steroids for psoriasis, we mean anti-inflammatory corticosteroids. Topical corticosteroids are divided into seven different categories based upon strength. The mildest of these, class 7, includes over-the-counter hydrocortisone 1%. The strongest, class 1, consist of the "big gun" steroid creams, such as clobetasole.Why More Isn't Better
Class 1 steroids are not just a little stronger than class 7, they are exponentially stronger and, therefore, can cause more side effects. Using a too-strong steroid on the face can lead to acne, rosacea and the development of little red blood vessels called telangiectasia. The eyes can be damaged by strong steroids, leading to glaucoma and cataracts.
In the groin and armpits, stronger classes of steroid can cause large red stretch marks to develop, which are usually permanent. Also, continuous use of strong steroids on the same exact areas leads to thinning of the skin (atrophy), which can also be permanent.
Lastly, covering large areas of your body with potent steroid creams can lead to systemic absorption and loss of the body's ability to make its own natural cortisol. An overabundance of cortisone-related drugs can produce an exogenous adrenal insufficiency state.
For all the above reasons, I usually try to use the least potent steroid which will actually get the job done choosing carefully for variable such as patient age, location of psoriasis and amount of body surface to be treated.
More Than Grease
One of my patients used to always come to the office for refills: "I'm out of grease" he'd say. But topical corticosteroids come in all sorts of vehicles:- Ointments (petrolatum-based "grease")
- Creams (lighter and less greasy, much nicer to use on the face, groin or armpits)
- Oils (for whole-body treatment or for overnight scalp treatment)
- Gels (completely absorb and non-greasy, great for hairy areas)
- Foams (easy to spread and also good for scalp and hairy areas)
- Tapes (for thicker plaques such as elbows and knees)
In general, for a given active ingredient, ointments will be more potent than creams (but also more messy). Foams have proven to be very effective in that they tend to penetrate to deeper layers of the skin than other vehicles. Hence, a slightly less potent active ingredient may give more benefit if used as a foam.
