Rosacea is a chronic inflammatory skin disorder that mainly affects the central part of the face. Its typical features are episodic flushing, persistent redness (erythema), small raised bumps (papules), pus-filled spots (pustules), and visible dilated blood vessels (telangiectasia). In some people the skin thickens, and the eyes and eyelids may also be involved. The condition is not life-threatening, but it can cause considerable discomfort, burning or stinging, and psychological distress. Its cause is not fully understood, and no treatment cures it, although several therapies control its signs and symptoms. The name derives from the Latin rosaceus ("rose-coloured"), and the older term "acne rosacea" is misleading because rosacea is not a form of acne in the usual sense, although it can resemble it.
Classification and clinical features
Since the early 2000s, the most widely used framework has been the classification of the National Rosacea Society Expert Committee, which recognises four subtypes and one variant. The 2017 update retained this scheme, while later work has moved toward phenotype-based descriptions that reflect the underlying biology more closely.
Erythematotelangiectatic rosacea is characterised by flushing and persistent central facial redness, with or without visible small vessels. Some patients report only flushing, burning, or stinging, and the vessels are not essential for the diagnosis.
Papulopustular rosacea combines persistent central redness with transient crops of papules and pustules. It is the subtype most associated with inflammatory lesions that resemble acne, and it is the one in which psychological burden is most often reported.
Phymatous rosacea involves thickening of the skin, irregular surface nodularity, and enlargement of sebaceous tissue. The nose is most often affected, a form called rhinophyma, but the chin, forehead, cheeks, and ears can also be involved. Histologically, several variants are described.
Ocular rosacea involves the eyes and eyelids. Symptoms include dryness, tearing, burning, a gritty sensation, swollen lids, recurrent styes, and, in severe cases, corneal damage that can threaten vision. Ocular signs may precede skin signs, and some patients have ocular involvement without marked facial redness.
Granulomatous rosacea is a variant in which firm, non-inflammatory-looking yellow-brown or red papules or nodules appear. Rosacea fulminans is a rare, severe, rapidly evolving form that typically affects young women and is generally treated with systemic corticosteroids or isotretinoin.
Secondary features, which may occur alongside primary ones or on their own, include burning or stinging sensations, plaques, dry appearance, facial oedema, a peripheral distribution of lesions, and phymatous change. Many patients show features of more than one subtype, and these often develop in sequence. Each sign may also progress from mild to moderate to severe.
A proposed neurogenic subtype describes people who flush very easily and prominently, sometimes in association with other neurological or psychiatric conditions. It is not yet a formal category.
Epidemiology
Estimates of prevalence vary widely because of differences in diagnostic criteria and study populations. Reported figures range from about 1 to 20 percent worldwide, and pooled estimates for adults are often near 5 percent. The condition is most common in fair-skinned people, particularly those of Northern European descent, and is under-reported in darker skin, where erythema can be harder to recognise. Onset is usually after the age of 30, and the disease is most often seen in people aged roughly 30 to 50. Women are diagnosed more often, while men are more likely to develop phymatous changes. Prevalence figures from individual countries have ranged widely: a Swedish population study reported about 10 percent, and an Estonian study using NRS criteria reported about 22 percent.
Rosacea is not confined to adults. Initial manifestations of the classic types can appear from infancy, and childhood cases are often associated with ocular involvement. Childhood rosacea is frequently confused with acne vulgaris or perioral dermatitis, and internationally agreed diagnostic criteria for children have not yet been established.
Diagnosis
Diagnosis is clinical and rests on the characteristic appearance and history. No specific laboratory or imaging test exists. The age of onset and the absence of comedones (blackheads and whiteheads) help distinguish rosacea from acne. Dermatologists also exclude other conditions such as seborrhoeic dermatitis, contact dermatitis, systemic lupus erythematosus, perioral dermatitis, and steroid-induced skin changes, and they assess eye involvement when symptoms suggest it.
Pathophysiology
The pathogenesis of rosacea is multifactorial, and no single mechanism has been established. Current models combine abnormal blood-vessel behaviour, altered immune responses, and environmental triggers in a self-reinforcing cycle.
Vascular factors
Abnormal vasomotor control is thought to explain flushing and persistent erythema. Dilated vessels and impaired facial venous drainage have been proposed as contributors, and increased angiogenesis is observed in lesions. Vascular and neurovascular dysregulation are considered central to the redness and flushing that define several subtypes.
Innate immune dysregulation
Rosacea skin shows raised levels of several innate immune molecules, including Toll-like receptor 2 (TLR-2), the serine protease kallikrein-5 (KLK-5), the antimicrobial peptide cathelicidin, and matrix metalloproteinases. Cathelicidin is processed by kallikrein-5 into the peptide LL-37, which is abnormally abundant in lesions. Experimental work in mice has shown that LL-37 administration can produce rosacea-like lesions, and that blocking cathelicidin expression prevents the inflammatory response. Ultraviolet B radiation can activate TLR-2, providing a plausible route by which sunlight provokes flares. Neutrophil infiltration and increased interleukin-8 expression have been reported during active lesions.
Microorganisms
The mite Demodex folliculorum, which lives in hair follicles and sebaceous glands and is present in most adults, is found in greater numbers on the skin of people with rosacea. A systematic review and meta-analysis of case-control studies found higher mite density in patients than in controls. Whether the mites cause the disease, or simply accumulate in inflamed skin, remains unresolved, and direct evidence for a pathogenic role is lacking. Mite chitin may act as a pathogen-associated molecular pattern that triggers inflammation. Other proposed contributors include the skin bacterium Staphylococcus epidermidis and the stomach bacterium Helicobacter pylori. Eradication of H. pylori has improved rosacea in some patients, but the evidence is inconsistent.
Genetics and vitamin D
Family history of rosacea is commonly reported, and a genetic predisposition is suspected, although genetic studies remain limited. Some work has linked vitamin D signalling to cathelicidin expression, since a vitamin D response element has been identified in the cathelicidin gene promoter. Findings on vitamin D status in patients have been mixed.
Associations with systemic disease
Rosacea has been associated with cardiovascular disease, dyslipidaemia, hypertension, and glucose intolerance. Shared mechanisms such as cathelicidin activity, oxidative stress, and endoplasmic reticulum stress have been proposed as links. These associations are observational, and their direction and cause are not established.
Triggers and aggravating factors
Commonly reported triggers include sun exposure, heat, cold and wind, emotional stress, alcohol, hot drinks, spicy food, and strenuous exercise. Triggers vary between individuals, and self-reported lists are not always reliable. Diet has no consistent role in the disease as a whole. Some medications and substances can worsen it, including amiodarone, topical and nasal corticosteroids, and high doses of vitamins B6 and B12. Certain components of sunscreens have also been implicated in aggravating symptoms in some patients.
Treatment
Management is guided by subtype and severity, and many patients need a combination of approaches. General measures include identifying personal triggers, using gentle cleansers and moisturisers, applying broad-spectrum sunscreen with an SPF of 30 or higher, and avoiding excessive sun exposure. These measures are recommended for all subtypes.
For mild to moderate papulopustular disease, first-line topical agents include metronidazole and azelaic acid, and topical ivermectin is also used. Subantimicrobial-dose doxycycline, which reduces inflammation without the antibacterial effect of standard courses, is an established oral option for inflammatory lesions. Standard tetracyclines, macrolides, and isotretinoin are used in more severe cases, the last being reserved for resistant or severe disease because of its side-effect profile. Use of antibiotics also raises concerns about antibiotic resistance, which is one reason for preferring low-dose regimens.
For persistent facial redness, topical alpha-adrenergic agonists such as brimonidine and oxymetazoline reduce erythema, though their effects can wear off within hours and rebound redness can occur. Vascular lesions and flushing respond variably to laser and intense pulsed light treatments, which also help with telangiectasia. Phymatous rosacea is treated mainly with laser or other light-based therapies, with surgical correction used for advanced rhinophyma. Ocular rosacea requires lid hygiene and may be treated with topical cyclosporine and topical or systemic antibiotics, and ophthalmological review is advised for persistent symptoms.
Current treatments are not curative, and they have been criticised for focusing largely on erythema and papules and pustules. Ocular disease and the inflammatory phase of phymatous change have received comparatively little attention in clinical research, so long-term suppression and disease-modifying approaches remain an active area of study.
Impact and quality of life
Although rosacea is not a life-threatening disease, it causes substantial morbidity. Burning, stinging, and itching are common, and facial lesions can impair quality of life. Patients often report embarrassment and a fear of negative evaluation by others, and the condition has been linked to psychological distress and anxiety. Visible changes to the nose and face can be particularly distressing, and visual symptoms from ocular involvement can affect daily activities.
Controversies and open questions
Several points remain unresolved. The relative importance of vascular, immune, microbial, and genetic factors is disputed, and the question of whether Demodex is a cause or a consequence of the disease has not been settled. The boundaries between subtypes overlap in practice, which complicates research and comparison across studies. Prevalence estimates differ widely, partly because of inconsistent diagnostic criteria and limited data from darker-skinned populations. The proposed neurogenic subtype and phenotype-based classification systems have not yet been universally adopted. Finally, the apparent links with cardiovascular and metabolic disease, while biologically plausible, have not been shown to be causal.
References
- Rosacea: Diagnosis and Treatmentaafp.org
- Rosacea management: A comprehensive review - Sharma - 2022 - Journal of Cosmetic Dermatology - Wiley Online Libraryonlinelibrary.wiley.com
- Rosacea in childhood and adolescence: A reviewncbi.nlm.nih.gov
- Rosacea Management - PMC - NIHpmc.ncbi.nlm.nih.gov
- Rosacea: New Concepts in Classification and Treatment - PMCpmc.ncbi.nlm.nih.gov
- Rosacea: Background, Pathophysiology, Etiologyemedicine.medscape.com
- Rosacea - Dermatology - Merck Manual Professional Editionmerckmanuals.com
- Rosacea: An Overview of Its Etiological Factors, Pathogenesis, Classification and Therapy Optionsmdpi.com
- Frontiersfrontiersin.org
- Evidence for the Clinical Association between Demodex and Rosacea: A Reviewkarger.com
- Rosacea: Molecular Mechanisms and Management of a Chronic Cutaneous Inflammatory Conditionmdpi.com
- A Study on Vitamin D and Cathelicidin Status in Patients with Rosacea: Serum Level and Tissue Expression - :: AD :: Annals of Dermatologyanndermatol.org
- Ocular Rosacea: Background, Pathophysiology, Epidemiologyemedicine.medscape.com