Puzzled by all the confusing terms used to describe acne? Here you’ll find important terms and definitions commonly used to describe acne, plus key ingredients and scientific procedures used to treat it.


A skin disorder cause by inflammation of the sebaceous glands and its attached hair follicles. Typically appears in regions where these glands and follicles are most prominent: face, neck, chest, shoulders, upper arms and back. Includes whiteheads, blackheads and pimples. Usually starts at puberty and can continue for several years.

A form of acne caused by aggravated heat, covered skin, constant pressure and repetitive friction against the skin. Common causes of acne mechanica are: helmet and helmet straps worn by football and hockey players, hats or caps worn for long periods of time, headbands worn for long periods of time, tight workout clothing/uniforms made of synthetic fabric, straps on backpacks and adhesive tape that remains on the skin for several days. Also referred to as sports-induced acne.

A liquid cosmetic used to cleanse the skin and contract the pores. Also referred to as a toner.


A powerful mixture of chlorides containing strong agents that work to keep skin immune from infections and acne bacteria. Its active agents help keep acne-bacteria spores from entering the pores and are considered to be extremely resistant.

A white crystalline compound (C14 H10 O4) typically used in acne medications. This effective ingredient works by introducing oxygen into the pores, killing acne bacteria that cannot survive in an oxygen-rich environment. It also helps prevent breakouts before they start by clearing dead skin cells that cause pore blockages.

A small, black-tipped lesion consisting of a clogged pore filled with sebum, bacteria and dead skin cells. The surface of lesion turns black because of melanin or because of a chemical reaction of the plug content with air. Similar to a whitehead but the pore stays open to the skin’s surface.


A large, dome-shaped lump, filled with pus, that’s usually inflamed and painful. Can become infected and cause scarring.

A thickened secretion consisting of a clogged pore, characterized by a flesh-tone bump (whitehead) or as a flat, rounded or slightly raised pore containing dark material (blackhead).


The dense inner layer of skin beneath epidermis. Is composed of connective tissue, blood and lymph vessels, sweat glands and hair follicles. Is involved in many important skin functions, including wound healing.

A doctor who specializes in the treatment of diseases of the skin.

Cells that build up on the surface of the skin and act as a barrier to absorb from nourishing creams and lotions and also block sweat glands, which can result in whiteheads, blackheads or acne.


The process of removing dead skin cells from the skin surface. Can be done by using topical skincare medications, chemicals, scrubs or medical instruments.

The outer, non-sensitive layer of the skin. It has various functions, the most important being to act as a barrier against harmful environmental factors.


A botanical ingredient derived from the gorgonian plant (also known as sea whip), known to help minimize redness and inflammation in the skin.


A small canal in the epidermis of the skin, where hair develops.

Various chemical substances that circulate through the body and regulate cell/body functions.

Coloration of the skin. In acne, it usually appears at the site of a pimple and discoloration can last for a while.


A red, inflamed acne lesion, also known as a pimple. Usually has a while/yellow pus pocket in the center of the lesion. Can be slightly raised and tender to the touch.


An abnormal structural change in your pore.


A lesion that differs in color from its surrounding skin, resulting from old acne lesions.

A visible stain on the skin. Can be caused by acne.

Any variations of black, dark brown, reddish-brown or yellow pigments in the skin.


A small, abnormal node, mass or lump lodged deep within the skin. Usually occurs with severe acne and may appear as an inflamed, deep, red bump that’s larger than a pimple. Can be painful and lead to scarring.
A severe type of acne characterized by several nodules/cysts. Lesions are inflamed, painful, large and contain pus. Will often produce scarring.

A lesion that is not inflamed/red. Examples of non-inflammatory lesions are blackheads and whiteheads.


An inflamed lesion that usually appears as small, pink bump on the skin, which can be tender to the touch. Also referred to as a pimple. Papules do not have pus at the center of the lesion.
Pimple is the common name for a papule or pustule and can refer to either one. These raised, reddish, tender spots are early signals of inflammation or infection of the hair follicle.

A small, inflamed, bump topped by a white or yellow pus-filled lesion that may be red at the base. Differs from a papule because of the pus located in the center of the lesion. Also referred to as a pimple.


Retinoids are a group of vitamin A derivatives that boost cell turnover, helping to smooth fine lines, even out skin tone, improve skin elasticity and unclog pores (which helps benzoyl peroxide medication to work more effectively). Retinoids can also help prevent acne outbreaks by preventing dead skin cells and sebum from clogging pores in the first place. Once applied to skin, retinols are converted to retinoids, then to the final, active form of retinoic acid. Retinols typically take longer to convert to retinoid acid, one exception being Retinol PLUS from University Medical, which is formulated with an innovative booster to speed up the conversion.


Skin care medication used to treat individual acne lesions.
Glands that produce oil called sebum. These glands secrete oil to hair follicles, which lubricate hair and skin. Most sebaceous glands are found on the face, neck, chest, shoulders, upper arms and back.

A fatty secretion of the sebaceous glands that lubricates hair and skin. Reaches the surface of the skin through the pores. Too much sebum production can clog pores and result in acne.

A crystalline phenolic acid (C7 H6 O3) found in many over-the-counter acne treatment products. Works by dissolving dead skin cells inside hair follicles, which unclogs pores. Can also be used as a preventative medication to stop new clogged pores from forming.

The action of removing dead skin cells, i.e. exfoliate.


A liquid cosmetic for cleansing the skin and contracting the pores. Also known as astringent.


Formed by a pore completely blocked with dead skin cells and sebum. Since no air can get into a completely plugged pore, it won’t get dark like a blackhead.


Common slang for a small, inflamed lesion, also known as a pimple.