Comedone
The clogged pore that quietly precedes a breakout. Comedones come in two forms, both early in the acne lifecycle, and both worth tracking before they turn into something else.
Definition
A comedone is a hair follicle clogged with sebum (skin oil) and dead skin cells. It is the earliest visible stage of acne. Comedones are non-inflammatory, which means they are not red or painful yet. If the clog reaches air, it oxidizes and darkens into an open comedone (a blackhead). If the clog stays sealed under the skin, it stays light colored and bumpy (a closed comedone, often called a whitehead, though that name causes confusion with pustules).
Open versus closed
- Open comedone (blackhead): Clog reaches the surface and oxidizes. Looks like a small dark dot, often on the nose, cheeks, or forehead.
- Closed comedone (whitehead): Clog stays sealed. Looks like a small flesh-colored or white bump under the skin. Usually clusters on the cheeks, jawline, or forehead.
How to recognize one (vs other acne types)
Comedones do not have a red halo around them. They are not painful. If the bump is red, raised, and tender, it has moved past comedonal stage into an inflammatory lesion (papule). If there is visible pus, it is a pustule. The skincare actives that work on comedones (gentle exfoliants, retinoids over weeks) do not work the same way as treatments for inflammatory lesions, which is why telling them apart matters.
Why counting comedones is useful
Most skincare products that target acne (retinoids, salicylic acid, benzoyl peroxide, azelaic acid) work upstream by reducing how often a clog forms in the first place. A change you can actually measure in four to six weeks is comedone count going down. Inflammatory lesions are downstream and noisier signals. If you are testing whether a retinoid is working, watch the comedones.
How Trace measures comedones
Trace runs on-device computer vision on each daily face scan and detects comedones along with papules, pustules, and nodulocystic lesions. Counts are surfaced as a trend line across your thirty day single-product test, not as a single score. If comedones trend down across weeks while you held the rest of the routine fixed, the product you tested is probably the reason.
This is a glossary entry, not medical advice. If your comedones are severe, painful, scarring, or not responding to over-the-counter actives over six weeks, see a dermatologist.
Frequently asked
What is the difference between a comedone and a pimple?
Pimple is the colloquial word and covers both comedonal and inflammatory acne. A comedone is the specific early non-inflammatory clog (blackhead or whitehead). What most people call a pimple in the painful red sense is technically a papule or pustule, both inflammatory.
Are blackheads and whiteheads the same as comedones?
Yes. Blackhead is the casual name for an open comedone. Whitehead is the casual name for a closed comedone, although whitehead sometimes also gets used for pustules, which is a different lesion type. The clinical taxonomy keeps it clean: open and closed comedones.
How does Trace track comedones?
Trace detects and counts comedones from a daily standardized selfie, on device. You see a trend line across thirty days alongside papules, pustules, and nodulocystic lesions.