How Topical Steroids Work

What's the difference in efficiency and delivery

Steroid drug abuse. Credit: Peter Dazeley / Getty Images

Topical steroids are an easy way to treat our largest and most accessible organ: the skin. In fact, they are the mainstay treatment of many dermatologic conditions; especially since they have the benefit of applying the medication directly to the affected area and have less risk of systemic side effects of oral steroids. While these topical medications work, treatment can be a lengthy ordeal and for it to prove successful, it requires patient compliance.

How Topical Steroids Work

Topical steroids work by reducing inflammation in the skin by several different mechanisms of action.

They alter chemicals that cause inflammation. Steroids, like cholesterol, estrogen and cortisone are natural occurring hormones made by the body. In response to stress or disease, the body releases these products into the blood stream to control the immune response. The steroid molecule is transported to the cell nucleus where it interacts with DNA. This interaction causes the cell to make proteins called lipocortins, which then turn off the production of a chemical called arachidonic acid. Without arachidonic acid many chemicals that cause inflammation in the skin and in the rest of the body are not produced, thus reducing inflammation. These powerful inflammatory chemicals include prostaglandins, leukotrienes, and platelet-activating factor.

They change immune system cells. Topical steroids also change the function of the cells of the immune system.

White blood cells don't recognize foreign cells as well and have a decreased capacity of fight off these foreign cells.

They constrict blood vessels. An immediate effect of topical steroids is to cause the small blood vessels called capillaries to constrict. A section of skin that has dilated capillaries will be red, warm, and swollen.

Therefore causing the capillaries to constrict decreases redness, warmth, and swelling.

Types of Topical Steroids

It is this ability to constrict the capillaries that place topical steroids into one of seven different classes. The most potent is Class I and these topical steroids are approximately 600-1000 times stronger than the common over-the-counter preparation of hydrocortisone 1% which is a class VII.  It is important to remember that the strength of a steroid preparation is not proportional to the percent on the label. For example, a 0.01% class I steroid may be hundreds of times more potent than a 3% class VII preparation. When reading labels, keep the class scale in mind: Class I as most potent to class VII as least.

Some available delivery methods of the steroid include ointments, creams, lotions, gels and powders. The most potent vehicle for delivering topical steroids are ointments. Other preparations may tend to reflect the conditions that they are trying to help alleviate. For instance, since powders are good at absorbing excess moisture, protecting the skin against chaffing, and easily covering large areas of the body, topical steroids targeting diaper rash and fungal infections tend to be in powder form.

The most popular method for topical steroid delivery is cream, which is used for many dermatologic conditions, especially in areas where there are folds. Although they are generally weaker than ointments, their cosmetic appeal and high compliance rate offer distinct advantages over other methods. As mentioned before, compliance determines how effective and success topical steroids are.

Sources

American Osteopathic College of Dermatology. Steroids (Topical). Accessed March 5, 2016.

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