The most common skin condition in the United States, acne doesn’t discriminate based on age. Around 50 million Americans deal with some form of acne each year — a number that includes tweens and teens, as well as adults well over 40, according to the American Academy of Dermatology. While it’s less likely for an adult to have lasting, full-blown breakouts, acne is still very common, says Christine C. Kim, MD, a medical and cosmetic dermatologist in Los Angeles. Because of hormonal fluctuations, women are especially prone to getting pimples well past their teen years, she notes, particularly along the jawline and chin.

What Causes Acne?

Acne occurs when glands in the skin produce and secrete too much oil, called sebum. This extra sebum, along with dead skin cells, can plug up hair follicles and cause pimples known as whiteheads and blackheads — or what doctors refer to as “comedonal” acne. Blackheads and whiteheads are also referred to as noninflammatory acne because the pimples are not swollen, red, or sore. But sometimes a bacteria called Cutibacterium acnes (C. acnes), which lives at the base of the hair follicles, gets into pores; this causes inflammatory acne. Pimples with an inflammatory component are referred to as pustules, nodules, and cysts, says Dr. Kim. “Most people have a component of both comedonal [noninflammatory] and inflammatory acne,” she explains. RELATED: 7 Easy Home Remedies for Acne

The Ultimate Acne Cheat Sheet: An A to Z Glossary of Terms

If any of the terms above sound unfamiliar, the following cheat sheet is for you. Knowing the terms for different types of acne and pimple treatments can help you better understand why you have breakouts, as well as suss out the best products for keeping skin clear and getting rid of zits when they pop up. What follows is a guide to the most common terms doctors use to talk about acne. If you or your teenager is dealing with acne, you’re likely to encounter at least some of these words. Acne Conglobata A rare and severe type of acne in which deep, inflamed bumps (nodules) are connected to each other beneath the skin’s surface. This type of acne can occur on the face, shoulders, chest, upper arms, buttocks, and thighs, and is often associated with scarring. Acne Mechanica A type of acne that results from wearing sports equipment or synthetic clothing that traps heat and sweat, and also rubs against the skin. If you have acne-prone skin, warmth combined with moisture and friction can lead to breakouts. Acne Vulgaris The medical term for common acne, it refers to acne that includes one of more of the following: blackheads, whiteheads, papules (small, or early, pimples that don’t contain any pus), and/or pustules (pus-filled pimples). Androgens The “male” sex hormones, such as testosterone. They are also present in women but in lower levels. Androgens cause the sebaceous (oil) glands to enlarge and produce more sebum, which is an important factor in causing acne. Males tend to have more severe acne than females. Antibiotics A large category of drugs that target bacteria in the body. Certain oral antibiotics, such as doxycycline, get rid of bacteria that contributes to acne. Azelaic Acid A natural acid that lessens skin inflammation and kills acne-causing bacteria. Azelaic acid is used as a topical treatment for mild to moderate acne. Bacne A combination of the words “back” and “acne.” This is an informal way of saying that you have acne that’s located on your back. Benzoyl Peroxide An antibacterial ingredient found in many topical acne products that can also help decongest (unclog) pores. Blackhead A noninflammatory pimple that occurs when a hair follicle gets filled with excess oil and dead skin cells. Blackheads are also called “open comedones” because the surface of the skin remains open. Exposure to air causes the opening of the follicle to oxidize and turn black. There is no active bacteria in this type of pimple. Blind Pimples The term for pimples that can be felt beneath the skin but not seen. Blind pimples form in the deeper layers of the skin and can be tender to the touch. Chemical Peel A treatment that involves applying a chemical (commonly salicylic, glycolic, or lactic acid) to the skin to stimulate exfoliation (removal) of the top layers of skin. Light and medium chemical peels may be recommended for acne or acne scars. Closed Comedo (Plural: Comedones) Also known as a whitehead, this is a noninflammatory type of pimple that forms when oils and skin cells plug up a hair follicle and the opening of the follicle closes up. Because the top of the pimple is covered with a thin layer of skin, it appears white or light-toned on its surface. There is no active bacteria in this type of pimple. Comedo (Plural: Comedones) An acne lesion, or pimple, that is not inflamed and does not have any active bacteria. Whiteheads and blackheads fall into this category. Comedogenic Ingredients in makeup or skin-care products that clog pores and can cause blackheads or whiteheads. Cortisone Injection A steroid drug that is injected into a cyst or nodule in order to bring down severe inflammation. Cutibacterium Acne (C. Acnes) A type of bacteria at the base of hair follicles that’s involved in the formation of acne. Cystic Acne Larger-than-average pimples that penetrate deep into the skin tissues and can leave behind a scar. Dermis The thick layer of the skin lying below the epidermis (outermost layer of skin). The dermis contains connective tissue, blood vessels, oil, sweat glands, nerves, and hair follicles. Dermabrasion A skin-resurfacing procedure that uses a rapidly rotating device to remove the outer layer of skin. The skin that grows back is usually smoother. Dermatologists often use dermabrasion to get rid of nearly flat (not too deep) acne scars. Epidermis The outermost layer of the skin. Excoriation Disorder A mental disorder in which people have an uncontrollable desire to pick, scratch, or rub acne lesions. Excoriation disorder falls on the obsessive-compulsive disorder spectrum. Exfoliation The process of removing dead skin cells from the outer layer of your skin. Mechanical exfoliation uses a tool, such as a brush, sponge, or a scrub, to physically remove dead skin cells. Chemical exfoliation uses chemicals, such as alpha and beta hydroxy acids, to gently dissolve dead skin cells. Follicle (or Hair Follicle) A small opening in the skin where hair grows and sebum (oil) is excreted. Follicles start in the dermis and connect to the surface of the skin. There are hundreds of hair follicles on the face, most of which contain miniature, invisible hairs. Blockage of a hair follicle, called a follicular plug, is an early step in the formation of all types of acne. Hormonal Acne Breakouts that occur due to hormone fluctuations or imbalances. This type of acne commonly occurs during teenage years, as rising testosterone increases oil production in the skin. During menopause, falling estrogen levels can also trigger acne. Inflammatory In acne, this term is used to describe a pimple that’s red, inflamed, tender, or filled with pus. Isotretinoin (Accutane) An oral acne medication that is prescribed to treat severe acne that involves deep, painful cysts and nodules. This is the only acne treatment that attacks all four causes of acne — excess oil production, clogged pores, too much of the bacteria C. acnes, and inflammation. Due to potential birth defects, a woman must not take this medication while pregnant or breast-feeding and must not become pregnant while taking it. Laser Therapy A treatment that uses a laser (a machine that produces a single band of light) to reduce C. acnes bacteria and sebum (oil), both of which contribute to acne. Laser therapy can help calm inflamed skin as well. Laser treatment for acne normally involves about three sessions at a doctor’s office. Lesion An area of skin, such as a pimple, that looks or feels different from the surrounding skin. Macule A flat spot, or a patch of skin, that is not the same color as the surrounding skin. Maskne Acne related to wearing face masks during the COVID-19 pandemic. Maskne is a form of acne mechanica (see above) and can cause breakouts in the areas covered by a face mask, such as the jaw, cheeks, nose, chin, and around the mouth. Melanin A substance that gives hair and skin its color. Microcomedo The first stage of comedo (whitehead or blackhead) formation. A microcomedo can only be seen with a microscope. Microdermabrasion A treatment that uses a minimally abrasive instrument to gently remove (or “sand” off) the thicker, uneven outer layer of dead skin cells. It may be used to treat acne and also to reduce acne scarring. Some microdermabrasion instruments have suction to vacuum the loosened skin cells from the face. Milia Milia are tiny, hard cysts that form on the skin. These bumps form when keratin, a type of protein found in surface skin cells, gets trapped under the outer layer of skin. Milia bumps look like whiteheads, but they are not acne. Unlike acne, they don’t develop in a pore and do not become inflamed. Multi-factorial A term that dermatologists use to describe how and why acne forms, which typically involves multiple factors, including bacteria, oil, excess skin cell shedding, medication, hormones, stress, and diet. Nodulocystic Acne A severe form of acne that causes numerous, deep, inflamed bumps (nodules) and large, pus-filled lesions (cysts). The nodules can be tender when touched and feel firm; cysts can also be tender but are fluid-filled so they feel soft to the touch. Scarring can result when the acne heals. Noncomedogenic Not likely to clog pores and cause comedones, or pimples. Noninflammatory In acne, this refers to comedones (pimples) that are not associated with redness/discoloration or swelling in the skin. Blackheads and whiteheads are noninflammatory. Open Comedo Also known as a blackhead, this is a noninflammatory comedo (pimple) that occurs when a hair follicle gets filled with excess oil and dead skin cells. Because the surface of the follicle remains open and exposed to air, it oxidizes and turns black. There is no active bacteria in this type of pimple. Oral Contraceptives Commonly called “the pill,” these birth control medications may be prescribed as acne treatment for some women. Oral contraceptives that contain both estrogen and progesterone can help reduce production of androgens, a group of hormones that stimulate skin to produce sebum (oil), which contributes to acne. Papule A small, slightly elevated, red/discolored bump, also known as an “early pimple.” Papules occur when a pore becomes clogged with excess oil, bacteria, and dead skin cells. If you have a lot of papules, the area may feel like sandpaper. After a few days, papules normally fill with pus and develop a white or yellow center, at which point they are called pustules. Papulopustular A type of acne that includes papules (see above) and pustules (pus-filled pimples). Pilosebaceous Unit The grouping (or unit) that contains the hair follicle and attached sebaceous (oil) gland. Pimple The common term for inflamed bumps or lesions on the skin. Pore Small openings on the skin. Pores are where hair follicles (which extend downward through several layers of skin) open on the surface of the skin. Post-Inflammatory Hyperpigmentation Darkened skin that occurs where an inflamed pimple was located. Part of the skin’s natural response to inflammation is to deposit melanin (pigment) into the skin. Post-inflammatory hyperpigmentation can be a particular concern in skin of color. Propionibacterium Acnes (P. Acnes) The former name of Cutibacterium acnes (C. acnes), a bacteria on the skin surface that contributes to acne. While you might still see either P. acnes or C. acnes used to describe the same acne-causing bacteria, scientists recently found that C. acnes is the more accurate name. Pustule A pus-filled pimple that often has a yellow or white center. Pseudocyst A pocket of fluid that forms under the skin. A pseudocyst can develop after long-term irritation or repeated injury to the area. Retinoid A type of prescription acne treatment that is a derivative of vitamin A. Retinoids can penetrate the skin beyond the epidermis and help unclog pores and speed up cellular turnover. Retinoids can also help fade acne scars. Over-the-counter versions are called retinols. Salicylic Acid An ingredient commonly found in over-the-counter acne treatments. Salicylic acid helps gently exfoliate the upper layers of the skin and can break down the excess oil and dead skin cells within hair follicles. Sebaceous Glands Oil-producing glands located in the deeper layers of the skin. These glands are attached to hair follicles and the oil they produce travels up the follicle to end up on the surface of the skin. Seborrhoea Excessively oily skin. Seborrhoea is due to overactive sebaceous (oil-producing) glands. The scalp and face are most commonly affected, but seborrhoea can also affect folds of skin, such as the underarms and under the breasts. Sebum An oily secretion of the sebaceous gland that helps to preserve the flexibility of the hair and skin. Sebum can cause acne when too much is produced. Steroid Acne A type of acne that occurs as a side effect of using corticosteroid drugs for too long. To avoid this skin complication, corticosteroid medications are typically prescribed for a limited time. Sulfur A natural element that can cause the skin to dry and peel. Sulfur also inhibits bacterial growth. This ingredient can be found in both prescription and over-the-counter acne treatment products. Systemic Treatment  A type of medication that is taken internally, rather than just being applied to the skin. This includes pills, injections, and infusions. Topical Treatment A type of treatment that is applied to the skin, such as a lotion, cream, or gel. Whitehead A noninflammatory pimple that forms when oil and skin cells block the opening of a hair follicle. Whiteheads are also called “closed comedones.” Because the top is covered with a thin layer of skin, it appears white or light-toned on its surface. Zit A slang term for a pimple.