Ask the Ecz-perts: Proper use of steroids, what’s in a blister, causes of eczema

Ask the Ecz-perts

By Kathryn Jones

Published On: Aug 10, 2017

Last Updated On: Oct 23, 2020

In Ask the Ecz-perts, leading medical experts answer your most pressing questions about eczema and its related conditions.

In this edition of Ask the Ecz-perts, dermatologist John Hanifin, MD, professor of dermatology Oregon Health and Sciences University, answers your questions about the causes of eczema, what’s in a blister and the proper way to use steroids.

What causes a person to get eczema on his or her body?

Atopic dermatitis is the most common type of eczema and has a genetic basis. Genetic defects in the skin barrier seem to account for many, if not most, cases.

The defective skin barrier allows chemical and physical irritants and bacterial toxins to trigger inflammation that causes redness and itching.

Protein allergens (for example, foods and pollens) also traverse the barrier and generate the immunoglobulin (IgE) antibodies that can cause asthma, hay fever and hives. Chemical allergens (for example, nickel and black dye) get through more easily too, and cause allergic contact dermatitis.

The main place I get eczema is on my hands. When I have a flare-up, it starts with small, clear-fluid, blisters on my hands. What is that clear fluid? And how can I prevent the blisters from forming in the first place?

The fluid is serum, which comes in when the skin is inflamed and forms the tiny blisters (eczema is from the Greek word “to boil over or effervesce”).

The inflammation must be stopped quickly using potent topical steroids applied to wet, hydrated skin. Hand dermatitis is the hardest of all the eczemas to treat. If it is caused by a contact allergy, dermatologists can do patch tests to detect the offending chemicals.

My doctor prescribed topical steroids for my eczema, but I am concerned about using them. Any suggestions?

Topical corticosteroids are very effective and if used properly, very safe. A major reason for failure is when there is an inappropriate prescription of low-potency steroids and the starting and stopping of regimens that never really control and stabilize the inflammation.

Sometimes I don’t follow my doctor’s directions concerning my eczema and steroid medications. What do I need to know to use topical steroids correctly?

Managing eczema is confusing, so the details are important. Doctors complain that patients don’t follow advice. Probably just as often, patients don’t understand what was advised. It’s best to plan a follow-up visit one to two weeks after a steroid is prescribed to clarify instructions and enhance control of eczema if possible. Ask questions and demand clear answers.

Here are some common mistakes to be aware of in topical steroid therapy:

  • Not treating new flares promptly and aggressively
  • Not hydrating skin before applying a steroid
  • Inadequate steroid potency (this is often the doctor’s fault)
  • Using different strengths for face and body
  • Diluting the steroid, perhaps by applying moisturizers on top of the steroid
  • Stopping use instead of maintaining control
  • Letting the prescription run out
  • Not calling the doctor for help promptly

How often should I be applying topical steroids?

Topical corticosteroids are a mainstay of eczema therapy. Results are often suboptimal because of steroid phobia and mistakes in applying the steroids. The drugs are safe if we focus on two crucial factors: frequency and duration.

Here are some suggestions for proper use of topical corticosteroids:

  • Apply to hydrated skin (after bath, shower or wet compresses).
  • Generally speaking, and based on your doctor’s directions, begin with twice daily applications for durations of no more than three days for face, eyelids, neck and folds and seven to 21 days for other areas.
  • Taper frequency to every two to three days (don’t stop). Twice weekly is safe for the long term, even for stronger steroids, and for any skin area.
  • Unless the eczema is very mild, it is best to use at least mid-strength steroid ointments, but remember: frequency and duration determine benefits and safety.

Do you have a question for our ecz-perts? Email them to

Dr. Hanifin is an expert in atopic dermatitisDr. John Hanifin is a Professor of Dermatology, School of Medicine at Oregon Health and Sciences University. He is an international lecturer and recognized expert in the research and treatment of atopic dermatitis, and has directed various national and international symposiums on this subject. Dr. Hanifin is a valued member of the research community, respected for his investigations into the clinical, biological and genetic aspects of the atopic diseases, as well as other allergic and inflammatory conditions. Dr. Hanifin helped to found the National Eczema Association and is a long-term member of the NEA Board of Directors and Scientific Advisory Board.