Reference
The rosacea glossary
Rosacea comes with a vocabulary, and a lot of it shows up in research papers and on your dermatologist's notes without explanation. Here is the plain-language version of the terms worth knowing, with sources where the meaning has shifted. This is informational, not medical advice.
Phenotype
A way of describing rosacea by the specific features you actually have, persistent redness, bumps, visible vessels, eye involvement, rather than sorting you into a fixed category. The phenotype approach replaced the older subtype model as the dermatology standard following the National Rosacea Society Expert Committee update and the global ROSCO consensus in 2017 to 2018. It is why a good tracker records features, not a label.
Subtype (the older model)
The earlier system that sorted rosacea into four types (erythematotelangiectatic, papulopustular, phymatous, and ocular). It was retired in favor of the phenotype approach because many people had features spanning more than one subtype. You may still see subtype language in older articles and apps.
Erythema
Redness of the skin caused by widened blood vessels. In rosacea it often shows up as persistent redness across the central face (cheeks, nose, chin, forehead). On darker skin tones it can be harder to see, which is part of why rosacea is under-diagnosed in people of color.
Flushing
A transient wave of redness and warmth, set off by things like heat, emotion, alcohol, exercise, or spicy food. Flushing comes and goes, which is exactly why it is hard to remember accurately later, and why a photo taken during one is worth more than a memory of it.
Telangiectasia
Small blood vessels that become visible at the skin's surface, sometimes called spider veins. Common on the cheeks and around the nose in rosacea, and one of the features clinicians look for.
Papulopustular
A rosacea feature involving inflammatory bumps (papules) and pus-filled spots (pustules). It is sometimes mistaken for acne, but the underlying condition and treatment differ, which is one reason an accurate record helps your dermatologist.
Phymatous
Thickening of the skin, most familiar as rhinophyma (a thickened, enlarged nose). It is a less common feature and tends to develop over a longer period.
Ocular rosacea
Rosacea affecting the eyes and eyelids, with symptoms like dryness, grittiness, irritation, or redness. It can occur with or without visible skin symptoms, and is easy to overlook, so it is worth mentioning eye symptoms to your dermatologist.
Demodex
Microscopic mites that naturally live in everyone's skin. Higher densities are associated with rosacea, and the relationship is an active area of research into what drives the condition. Present in healthy skin too, so their role is about quantity and response, not simple presence.
Trigger
Anything that brings on or worsens a flare for a given person, sun, heat, stress, alcohol, and so on. The defining thing about triggers is that they are individual: the population list tells you where to look, but only your own tracking tells you yours.
Flare
An episode of worsening rosacea, more redness, more bumps, more sensitivity, usually following one or more triggers. Flares often have several inputs stacked together, which is why single-cause hunches frequently miss.
Baseline
What your skin looks like on an ordinary, non-flare day. Knowing your baseline is what lets you recognize a flare as a flare, and a consistent daily photo is how you establish it.
Vasodilation
The widening of blood vessels that produces the redness and warmth of flushing. Many rosacea triggers, heat, alcohol, exercise, work through this same mechanism, which is part of why heat-related triggers dominate the survey data.
Put the vocabulary to work on your own skin.
Skinframe records the features you actually have, photographs them daily, and helps you find the triggers behind your flares, then turns it into a record you can bring to your dermatologist. Your photos stay in your own iCloud. One-time $29.99, or $4.99 a month with one-tap cancel.
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