Rosacea (commonly called 酒糟肌) — complete patient guide
Phenotypes, treatment ladder, Demodex, myth-busting

What is rosacea?

Rosacea (Chinese folk name 酒糟肌, formally renamed 玫瑰斑 by the Taiwan Dermatological Association in 2022) is a chronic inflammatory disease affecting the central face. Lifetime prevalence is around 5% of adults, peaking at age 30-50, more visible in lighter skin tones but seen across all phototypes (Hampton 2021, BJD). The Chinese folk term 「酒糟」 (wine-residue) is a misleading translation — alcohol is just one trigger, not the cause; teetotalers also develop the disease. The English word "rosacea" simply means "rose-colored," describing appearance, not etiology.

Phenotype-based classification (replacing old subtypes)

BAD 2021 (R3-R4) and the 2022 German S2k guideline have formally abandoned subtypes I-IV (ETR / PPR / phymatous / ocular) in favor of a phenotype-based approach. Diagnosis requires 1 diagnostic feature (persistent centrofacial erythema or phymatous change) or ≥ 2 major features (flushing, papules/pustules, telangiectasia, ocular changes). One patient may exhibit several phenotypes simultaneously; each is treated separately.

Pathogenesis and the role of Demodex

Rosacea pathogenesis is multifactorial: neurovascular dysregulation, innate immune over-activation (TLR2 / cathelicidin LL-37), barrier dysfunction, sebaceous-gland abnormality, microbiome dysbiosis (notably Demodex overgrowth), genetic predisposition, and environmental triggers.

Demodex folliculorum (in upper hair follicles) and Demodex brevis (in deeper sebaceous glands) are normal commensals on 20-80% of healthy adults. In rosacea patients, density is 5-10× higher (typically > 5/cm²), particularly in the papulopustular and ocular phenotypes. Mite-associated Bacillus oleronius proteins activate innate immunity via TLR2; dead mites act as persistent antigens. BAD 2021 frames Demodex as a contributor, not the sole cause, and only some patients benefit from anti-Demodex therapy (Hampton 2021, BJD). Topical ivermectin's primary action is anti-inflammatory; anti-parasitic action is secondary. So — killing mites alone is insufficient; concurrent anti-inflammatory care is required.

Diagnosis and Demodex testing

Rosacea is primarily a clinical diagnosis. Differential diagnoses include seborrheic dermatitis, acne vulgaris, contact dermatitis, lupus (malar rash), and dermatomyositis. Adjunctive tests — only when needed — include dermoscopy (vascular network, follicular plugs, "Demodex tails"), standardized skin surface biopsy (SSSB) with cyanoacrylate (> 5 mites/cm² is significant), skin biopsy for atypical or suspected granulomatous cases, and reflectance confocal microscopy (research only). Routine mite testing is not required — most patients can be treated based on phenotype.

Six common patient myths

Myth 1: Rosacea is caused by drinking too much

The Chinese name 「酒糟」 (wine-residue) refers to the appearance — flushing and redness like a drunk person — not the cause. The English term "rosacea" simply means "rose-colored." Real pathogenesis: chronic inflammation involving innate immunity, vascular hyperreactivity, neurovascular dysregulation, and likely Demodex mite involvement.

Myth 2: Rosacea is just sensitive / allergic skin

Differences:

Myth 3: Rosacea is caused by mites — kill them and it's cured

Demodex mite density is higher in rosacea patients vs healthy controls (5× higher). 2022 German S2k guideline recommends Ivermectin 1% cream once daily as first-line for inflammatory rosacea — its efficacy comes from both anti-inflammatory and anti-parasitic action.

Myth 4: Since it's red bumps, retinoids should help

Exception: oral low-dose isotretinoin (0.25-0.30 mg/kg/day) is recommended by 2022 German S2k for refractory granulomatous or papulopustular rosacea, under specialist supervision. Don't apply over-the-counter retinoids to red, burning skin.

Myth 5: Cold compress with toner / cosmetic pad feels better

Avoid in rosacea-prone skin:

• Alcohol denat / ethanol, menthol, camphor, eucalyptus, cinnamon, spicy essential oils
• AHAs / high-strength salicylic acid / topical retinoids
• Fragrance, dyes
• Physical scrubs, cleansing brushes, over-cleansing

For redness relief: ice wrapped in a clean towel or chilled mineral water on a damp cloth, 5-10 min. Then a gentle moisturizer with ceramide, hyaluronic acid, or 4-5% niacinamide.

Myth 6: Rosacea is incurable — you must avoid everything forever

Modern strategy by phenotype:

• Persistent erythema: Brimonidine + sun protection + barrier repair
• Papules / pustules: Metronidazole or Ivermectin or Azelaic acid + low-dose Doxycycline 40 mg if needed
• Telangiectasia: vascular laser (PDL / V Beam) or IPL — definitive treatment for visible vessels
• Rhinophyma: oral isotretinoin or laser ablation / surgery

Treatment ladder (BAD 2021 + 2022 German S2k + ROSCO + TDA 2022)

Key points at a glance:

• Phenotype-based classification replaces old subtypes (BAD 2021 R3-R4).
• Topical first-line trio, equal status (R9, ↑↑, no preference): ivermectin 1% qd, metronidazole 0.75% bid, azelaic acid 15% gel bid.
• Topical for persistent erythema: brimonidine 0.33% gel (R11, ↑) or oxymetazoline 1% cream (R12, ↑; FDA approved 2017) — purely vasoconstrictive, not anti-inflammatory.
• Oral first-line (R13, ↑↑): sub-microbial doxycycline 40 mg modified-release qd (or doxycycline 100 mg qd).
• AVOID minocycline (R14, ↑↑ AGAINST): drug-induced lupus, DRESS syndrome, and skin/teeth pigmentation risk significantly higher than other tetracyclines.
• Antimicrobial stewardship (R5, GPP): avoid prolonged oral antibiotics; reassess at 8-16 weeks.
• Refractory (R15, ↑): low-dose oral isotretinoin 0.25-0.30 mg/kg/day (10-20 mg/day, 3-6 months).
• Refractory flushing (R16, ↑): oral propranolol or carvedilol (off-label); TDA 2022 also includes microbotox.
• Phymatous (R18): laser/surgical debulking (CO₂ ablative laser, Er:YAG, electrosurgery); early stage may try isotretinoin.
• Ocular rosacea (R19-R23, ↑↑): trigger avoidance, warm lid compress, lid hygiene, lubricants; review systemic medications that worsen the ocular surface (R20); refer to ophthalmology when refractory (R23).

Summary

Rosacea is not because the skin is "too fragile" — it's a real chronic inflammatory disease. The right prescription + the right skincare + identifying personal triggers = most patients reach near-symptom-free state. Stop scrubbing with cleansers and stop using acne retinoids. Visit a dermatologist for a personalized plan.