Cystic acne is classified as Grade 4, the most severe grade on standard acne grading scales. Whether your dermatologist uses the Pillsbury scale, the Global Acne Grading System (GAGS), or the Investigator Global Assessment (IGA), cystic lesions consistently land at the top of the severity spectrum alongside nodules.
How Acne Grading Works
Dermatologists don’t grade acne based on how many pimples you have alone. They look at the type of lesion, because deeper, more inflammatory spots cause more damage than surface-level ones. Most grading systems use a scale of 0 to 4, where each number corresponds to increasingly severe lesion types:
- Grade 0: Clear skin, no lesions
- Grade 1 (mild): Comedones, which are blackheads and whiteheads with no real inflammation
- Grade 2 (moderate): Papules, small raised red bumps
- Grade 3 (moderately severe): Pustules, inflamed bumps filled with pus
- Grade 4 (severe): Nodules and cysts, deep painful lumps beneath the skin
The Global Acne Grading System, developed in 1997, evaluates six body zones (forehead, each cheek, nose, chin, and chest/back) and scores each on this 0-to-4 lesion scale. The IGA scale used in clinical trials describes Grade 4 as skin where “inflammatory lesions predominate” with “many comedones and papules/pustules” and nodulocystic lesions present. In the most detailed version of that scale, Grade 4 means the entire face is involved, covered with numerous comedones, papules, pustules, and nodules or cysts.
Nodules vs. Cysts: Both Grade 4
You’ll often hear the terms “nodular acne” and “cystic acne” used interchangeably, and dermatologists frequently group them together as “nodulocystic acne.” Both sit at Grade 4, but they feel different. Nodules are firm, hard knots deep under the skin. Cysts are softer, fluid-filled lumps that form when blocked pores trap bacteria, dead skin cells, and oil beneath the surface. Both are painful, and many people have a mix of the two.
Only about 20% of people with acne develop a severe form like nodular or cystic acne. These lesions form when inflammation becomes intense enough to rupture the follicle wall. Bacteria, fatty acids, and debris spill into the deeper layers of skin, triggering the immune system to send white blood cells to the area. The result is those large, red or white, pus-filled bumps that can persist for weeks.
Why the Grade Matters for Treatment
Grade 4 acne typically doesn’t respond to over-the-counter products or even standard prescription creams and antibiotics. The American Academy of Dermatology recommends isotretinoin (commonly known by the former brand name Accutane) for severe, recalcitrant nodular and cystic acne that hasn’t cleared with other treatments. It’s the most effective option available for Grade 4 acne.
Treatment usually starts at a lower dose for the first four weeks to avoid an initial flare-up, then increases based on how well you tolerate it. A full course runs 15 to 20 weeks of daily use. About 85% of patients taking isotretinoin are virtually clear of acne by 16 weeks, and most are free of it entirely by four to six months. The goal is complete, long-lasting remission rather than just temporary improvement.
Scarring Risk at Grade 4
The biggest concern with cystic acne isn’t just the breakouts themselves. It’s the permanent scarring that can follow. Any acne spot can technically scar, but nodules and cysts carry the highest risk because they sit so deep in the skin. When these lesions burst, they damage surrounding tissue.
Three types of scars are most common after cystic acne. Ice pick scars are small, deep pits that look like the skin was punctured with a sharp point. Rolling scars form when bands of scar tissue develop beneath the surface, creating a wavy, uneven texture. Boxcar scars are round or oval depressions, almost like shallow craters. Early treatment of Grade 4 acne is one of the most effective ways to prevent these scars from forming in the first place, which is a key reason dermatologists move quickly to stronger therapies when cysts and nodules are present.
Getting an Accurate Grade
If you suspect your acne is Grade 4, a dermatologist can confirm it by examining the types and distribution of your lesions. They’ll look at whether you have deep, painful lumps (not just surface spots), how much of your face or body is affected, and whether you’re already developing scarring. A single cyst doesn’t necessarily mean your overall acne is Grade 4, since grading considers the full picture of what’s happening across your skin. But if nodules or cysts are a regular feature of your breakouts, that consistently places your acne at the most severe end of the scale.