Differentiating Between Eczema and a Rash

By Lois Zoppi, B.A.Reviewed by Dr. Liji Thomas, MD

There are many types of skin conditions that present similar symptoms, and it can be difficult to tell what kind of skin problem a patient is experiencing. Rashes are areas of irritated skin that can be red, painful, swollen, or itchy, and they can lead to blisters. Typically, eczema is found in the creases of the skin and is characterized by itchy, dry, and red skin.

Eczema. Image Credit: Pumatokoh

Diagnosing Eczema

It can be very difficult to tell a rash apart from eczema by visual examination, but unlike most rashes, eczema is a long-term condition.

Biopsies may be taken to determine the type of skin irritation present, although a full clinical investigation including the patient’s history, existing medical conditions and any familial traits that may point to an increased risk of eczema, can help determine what type of skin irritation has occurred before biopsies become necessary.

There are several factors that will lead to a diagnosis of atopic eczema over a rash, beginning with a history of experiencing an itchy skin condition in the last 12 months, combined with three or more of the symptoms below:

• Visibly irritated skin in the creases present on medical examination
• A history of skin irritation
• Dry skin in the last 12 months
• Asthma or hay fever in adults, or an immediate relative with either condition in children under four years old
• Onset under the age of two years

Differentiating Rashes and Eczema

Timing

The timing of a rash after a possible exposure may be useful in distinguishing it from eczema. When a rash appears, it’s useful to consider what may have caused it throughout the day, such as a particular food or plant. However, not all rashes appear immediately, and some can take several days to develop. In general, rashes disappear quickly, but some rashes do require long-term treatment.

When skin reacts due to contact with an irritant, it is called contact dermatitis. The symptoms of contact dermatitis include a red rash, itching, burning, stinging, and blisters filled with liquid. Possible causes for skin reactions include:

• Eating foods you are allergic to
• Tobacco smoke
• Environmental factors - coming into contact with certain plants, such as poison ivy, can cause adverse skin reactions, as well as insect bites or allergens like pollen or animal dander.
• Irritants at home or in workplaces – these include paints, pesticides, or cement mixes. Prolonged periods of wet or damp skin can also cause skin irritation.
• Hygiene and beauty products – skin can react to soaps, perfumes, make up, deodorants or hair dyes. Certain metals, such as nickel found in some types of jewellery, can also cause skin reactions.
• Clothing – wool can be a common skin irritant, and fabric treatments used when washing clothes can also cause skin irritation.

Triggers for eczema include

• Soap and detergents
• Cold and dry weather
• Damp weather
• Dust mites, fur, mould or pollen
• Cow’s milk, eggs, peanuts, soya or wheat
• Wool
• Hormonal changes
• Stress and excessive sweat
• Skin infections

Location

The location in which the rash appears, and the spread of the rash to another part of the body, are also important in offering clues to the diagnosis. Rashes are known to occur most commonly on certain parts of the body, such as the fungal rash called athlete’s foot between the toes. On the other hand, the most common places for eczema to occur are the hands, insides of the elbows, backs of the knees, the face and, in children, the scalp. Although the above areas are common points of irritation, eczema can affect any part of the body.

Symptoms

The symptoms may also be helpful, since both rashes and eczema may be itchy and dry. However, a painful condition is less likely to be due to eczema. The presence of fluid-filled blisters and bumps is diagnostic of eczema, and thickened skin, oozing and bleeding are all in favour of this condition.

What are the Different Types of Eczema?

There are a number of different types of eczema, further complicating the identification of a rash. The different types of eczema include:

• Dyshidrotic eczema – eczema affecting the fingers, palms, and soles of the feet
• Nummular eczema – dry, round patches of skin commonly occurring during the winter months
• Follicular eczema – eczema involving hair follicles
• Varicose or gravitational eczema – eczema affecting the lower legs, common in people with varicose veins
• Dermatitis herpetiformis – a skin condition linked to celiac disease
• Neurodermatitis – a skin condition exacerbated by the itch-scratch cycle. The condition starts with an itch and is sustained by scratching and results in thickened, leathery patches of skin
• Perioral eczema – an inflammatory rash around the mouth
• Asteatotic eczema – linked to a decrease in oils on the surface of the skin and causes dry, cracked skin with scaling.

Neurodermatitis cause. Lichen simplex is a skin condition that begins with an itch. The inch can develop any where on the surface of body ( eg. foot, arm, neck, back). Image Credit: Angel_Jaeng / Shutterstock

Summary

Although the clinical symptoms of rashes and eczema are very similar, the triggers and duration of the skin irritations can differ. While many rashes disappear quickly, eczema is typically a long-term condition requiring on-going management and treatment. An examination by a health professional is necessary to determine what kind of skin irritation a patient is experiencing.

Further Reading

• All Eczema Content
• What is Eczema?
• Eczema Types
• Eczema Treatment
• Eczema Research