You may come across some unfamiliar words when you are reading about atopic dermatitis. Usually these are technical medical terms used to describe specific concepts.

While we may not be able to list down every single new word you encounter, we can help you understand some of the more common ones. 

Words for Different Conditions

Let’s talk about the two most common words you probably come across, “eczema” and “atopic dermatitis”.

Eczema: General term for any skin condition where there are patches or spots of discoloration (usually red), itch, and inflammation.1-3 Different types of eczema include atopic dermatitis, contact dermatitis, seborrheic dermatitis, and statis dermatitis, among others.1 It can be hard to tell different types of eczema apart, you need a doctor’s diagnosis for that. Getting the correct diagnosis is important to getting the proper treatment.3

Atopic Dermatitis or AD: This is a specific disease condition and the most common type of eczema.1,3 Typically, it involves dry, itchy skin that is prone to flare-ups and rashes.1,3 Some people use the term “atopic eczema” or just “eczema” when they are actually talking about AD. It’s best to use the correct term to avoid confusion.

Atopy: A higher likelihood of developing allergy that passed down from parent to child.2 “Atopic” when used as an adjective, like in “atopic dermatitis”.

Dermatitis: Inflammation of the skin.1,2 It comes from the word “dermis” which refers to the skin. The word “dermis” is also used as a medical term for the inner layer of the skin. The outermost layer of the skin is called the “epidermis”, and the surface of the epidermis is what we normally see.2

Allergy: An exaggerated immune response to a substance in the environment.1,2 “Allergic” when used as an adjective, like in “allergic condition” or “allergic response’.

Inflammation: The immune system’s natural response to a potentially harmful substance or force.1,4 This is the body’s way of trying to protect itself.4 Characteristics of inflammation include pain, warmth, redness, swelling and loss of function, but not all of these need to be present.1,4 Sometimes inflammation occurs silently, without causing any symptoms that you can feel, but if it continues, it will eventually reach a level when symptoms start coming up.4

Symptoms names, descriptions, and related words

If you don’t exactly know what “symptom” means, it’s a word for anything that a person feels or sees on their body that may indicate a disease. Many words are used to describe different symptoms and what causes them, let’s look at some of these words.

Allergen: A substance that triggers an allergic response in some people.1,2 Allergens are usually specific to certain people, and do not trigger an allergic response in a person who does not have that particular allergy. Some examples are plant pollen, dust, animal dander, antibiotics, certain foods like peanuts or seafood.1

Atrophy: When used to describe the skin, this means the skin becomes thin and easily damaged.1

Chronic: Long lasting, happening over a long period of time.1,2 Usually used to describe a symptom, disease or condition that lasts for a long time.1 The opposite of “chronic” is “acute”, meaning something that only lasts for a short period of time.2 “Acute” can also be used to describe something that is severe that lasts for a short period of time.2

Flare or Flare-up: Used to describe a situation when AD symptoms like rash and itchiness reappear (after a period of absence) or get worse (if mild symptoms have always been present).1

Lichenification: Thickening of the skin, this usually makes the skin lines more prominent.5

Rash: A group of colored marks or spots that appear on the skin.2 Usually red, but can be a wide range of other colors like purple, brown, or grey.2 “Exanthem” is the more formal medical term for a skin rash.2 Specific medical terms are used to describe what a rash looks like:

Macule: Small flat area of color less than 1 cm. “Macular“ when used as an adjective, like in “macular rash’ to describe a lot of macules grouped together.5

Patch: Larger flat area of color bigger than 1 cm.5

Plaque: A raised or elevated patch, usually bigger than 1 cm.5

Papule: Small raised solid bump, usually round, less than 1 cm.5 “Papular“ when used as an adjective.

Nodule: Larger raised solid bump, usually round, greater than 1 cm.5 “Nodular“ when used as an adjective.

Vesicle: Small blister, filled with clear fluid, less than 1 cm.5 “Vesicular“ when used as an adjective.

Pustule: Vesicle that contains pus instead of fluid, less than 1 cm.5 “Pustular” when used as an adjective.

Bulla: Larger blister filled with fluid, bigger than 1 cm.5 ‘Bullous’ when used as an adjective.

Recurrent or Recurring: Something that keeps coming back.1

Striae: Medical term for stretch marks,1 dark streaks or stripes on the skin, usually tapering to points at the ends.

Words related to treatment

In this section we will define some of the words used when describing treatments or explaining them. Definitions of specific types of treatments can be found in separate articles. (Link to Treatment Options)

Alkali: A substance that has the opposite action as an acid, and is able to neutralize acids.1

Antioxidant: A substance intended to protect the cells of your body from the damaging effect of specific chemicals called “free radicals”. 1 Free radicals can damage cells and play a role in the development of many diseases.1

Astringent: A substance that is able to shrink or contract the skin temporarily, affecting only the area where it is applied.1

Cream: A semisolid mixture of oil and water, mostly oil, that is intended to be spread on top of the skin.1

Emollient: A substance intended to smooth, soften, and moisturize the skin.1

Emulsifier: A substance used to combine two liquids that ordinarily would not mix, like oil and water.1

Exfoliant: A substance used to remove dead skin on the surface of the epidermis, a process known as exfoliating or exfoliation.1

Fragrance: A substance, usually composed of several elements, that evaporates at room temperature to produce an odor.1 These are one of the main ingredients in perfumes and are typically made from dozens or even hundreds of different chemicals.1

Humectant: A substance intended to promote moisture retention.1

Hydrate: To add moisture. Another way of saying “moisturize”.1

Hypoallergenic: Designed to minimize the potential for triggering allergic reactions.1

Immunomodulator: A substance used to influence or modify the immune system or immune response.1

Lotion: A semisolid mixture of oil and water, mostly water, that is intended to be spread on top of the skin.1

Non-comedogenic: Used to describe something that is designed to minimize the potential to cause acne.1

Ointment: A clear, greasy semisolid preparation that contains no water, intended to be spread on top of the skin.1
Phototherapy: The use of light, in particular ultraviolet or UV light, to treat disease.1

Refractory: Not responding to treatment.1

Systemic: Describes something that affects or involves the whole body.1 Often used to differentiate from something that is “local”, meaning affecting only a specific part of the body.1

Topical: Pertains to the surface of the skin.1 Usually used to describe medication or preparations that are meant to be spread on the skin’s surface.


  1. National Eczema Association. (2017). “Glossary of skin care terms”,  (Accessed May 19, 2022).

  2. American Academy of Family Physicians. (2022) “Dictionary”, (Accessed May 19, 2022).

  3. Reference from Myth Busters

  4. Institute for Quality and Efficiency in Health Care (IQWiG); Cologne, Germany. (2010) “What is an inflammation?” Informed Updated February 22, 2018. (Accessed May 19,2022).

  5. Ko, J. “The general dermatology exam: learning the language”, Stanford Medicine.  (Accessed May 19,2022).

Health information contained herein is provided for general educational purposes only. Your healthcare professional is the single best source of information regarding your health. Please consult your healthcare professional if you have any questions about your health or treatment.