A pustular rash consists of crops of pustules—visible collections of pus within or beneath the epidermis, often in a hair follicle or sweat pore. Pustules can vary in size and shape and may be localized (e.g., folliculitis) or generalized. Although some pustules are sterile, a pustular rash usually signals infection. Secondary infection can complicate vesicular eruptions or acute contact dermatitis.

Pathophysiology

Pustules form due to accumulation of neutrophils and inflammatory cells within the epidermis or follicular unit. Causes include:

• Bacterial infection: Staphylococcus aureus, Streptococcus pyogenes

• Fungal infection: Blastomyces dermatitidis

• Viral infection: Varicella-zoster, monkeypox, smallpox

• Immune-mediated skin disorders: Psoriasis, acne vulgaris

• Mechanical or chemical irritation: Sweat, friction, saltwater exposure

• Drug-induced reactions: Bromides, iodides, lithium, corticosteroids, hormonal agents

History and Physical Examination

History should cover:

• Onset, progression, and distribution of pustules

• Preceding lesions (papules, vesicles, macules)

• Recent medications, topical applications, or exposure to irritants

• Family history of dermatologic conditions

• Associated systemic symptoms: fever, malaise, cough, lymphadenopathy

Physical examination:

• Inspect the entire skin surface for pustule morphology, size, color, and distribution

• Assess skin type (dry, oily, moist, greasy)

• Look for secondary signs: erythema, crusting, excoriations, ulceration

• Evaluate for involvement of hair follicles, sweat glands, mucosa, or skin folds

Common Medical Causes

Gender Considerations:

• Men: Glans, shaft, scrotum

• Women: Nipples

• Both: Predilection for skin folds (axillae, elbows, waistline, knees, ankles)

Other Causes

• Drugs: Bromides, iodides, lithium, corticosteroids, phenytoin, phenobarbital, hormonal contraceptives, anabolic steroids

• Environmental or irritant exposures: Salt water, friction, chemical irritants

Assessment and Diagnostic Workup

• Gram stain and culture of pustule content to identify infection

• Blood tests if systemic infection suspected (CBC, inflammatory markers)

• Skin biopsy for atypical or persistent lesions

• Isolation precautions for potentially contagious infections

Management principles

• Treat underlying cause (bacterial, viral, fungal, immune-mediated, or drug-induced)

• Maintain wound hygiene: avoid contact with healthy skin

• Pain and pruritus relief: topical corticosteroids, antihistamines, analgesics

• Emotional support: address anxiety, stress, and altered body image

• Isolation: limit spread for infectious causes

• Avoid self-medication with unverified topical creams

Patient counseling

• Educate about cause, treatment options, and infection prevention

• Encourage personal hygiene and avoidance of shared linens or personal items

• Teach strategies for relief of itching and pain

• Provide psychosocial support for stress or sleep disturbances

Pediatric considerations

• Common causes: varicella, erythema toxicum neonatorum, candidiasis, impetigo, infantile acropustulosis, acrodermatitis enteropathica

• Assess for secondary infection in neonates and immunocompromised children

• Monitor for systemic symptoms in viral pustular rashes

References

1. Buttaro TM, Tybulski J, Bailey PP, Sandberg-Cook J. Primary Care: A Collaborative Practice. St. Louis, MO: Mosby Elsevier; 2008.

2. Sommers MS, Brunner LS. Pocket Diseases. Philadelphia, PA: F.A. Davis; 2012.

3. Wolff K, Johnson RA. Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology, 6th ed. New York, NY: McGraw Hill Medical; 2009.