Eczema is diagnosed clinically based on history and a thorough physical examination of the skin. There are no laboratory or blood tests which can diagnose eczema. Laboratory tests may be done to identify an allergen or diagnose the cause of infection.
Medical history and examination: The doctor may ask question such as:
- Does the rash itch and how much does the itch bother you?
- When did the symptoms start?
- Does the rash increase and decrease in severity?
- Do you have a family history of atopic eczema?
- Do you have any other conditions that may be related to your eczema, such as allergies or asthma?
- Whether the skin condition aggravates with any changes in environment or contact with certain materials, and whether it is aggravated in any specific situations?
On examination the doctor will note:
- The affected skin (such as the front of your elbows, behind your knees, the front of your ankles, around your neck).
- Severity of your eczema.
- If the skin affected by eczema appears infected.
- How widespread the areas of dry skin are.
Inform your doctor if the skin condition is affecting your quality of life. For example, it disturbs sleep or limits your daily activities.
- Skin patch test: If eczema is suspected to be due to allergy (allergic contact dermatitis) the doctor may conduct allergy tests, which may include a skin "patch test," in an attempt to identify the specific trigger of the condition.
- Skin biopsy: Appearance of eczema is similar to many other diseases of the skin, including infections or reactions to certain medications, so it may not be easy to diagnose eczema. If the rash and symptoms do not respond to treatment for eczema, the doctor may perform skin biopsy to rule out other skin diseases that may be producing signs and symptoms similar to eczema.
Your doctor will work with you to identify factors which make your eczema worse. This may include keeping a diary about your diet and lifestyle to see if any obvious factors may be contributing to your symptoms (such as if some soaps or shampoos make the eczema worse). A food diary involves noting down whatever you eat and also making a record of any eczema flare-ups that you have. This can help your doctor to establish if there are any patterns between your symptoms and what you eat.