Author:
Editor(s):
Updated:
ULY CLINIC
ULY CLINIC
20 Septemba 2025, 01:51:44
Vesicular rash
A vesicular rash consists of blister-like lesions that are sharply circumscribed and filled with clear, cloudy, or bloody fluid. Individual lesions are usually less than 0.5 cm in diameter and may occur singly or in groups. Larger fluid-filled lesions (>0.5 cm) are termed bullae. Vesicular rashes can be mild or severe, temporary or chronic, and result from infection, inflammation, or allergic reactions.
Pathophysiology
Vesicular rashes result from disruption of the epidermal or dermo-epidermal junction, causing fluid accumulation between skin layers. Key mechanisms include:
Direct cytopathic effect of infectious agents: e.g., Herpes simplex virus or varicella-zoster virus infect keratinocytes, causing vesicle formation.
Immune-mediated reactions: e.g., dermatitis herpetiformis and erythema multiforme involve IgA or T-cell mediated damage to the epidermis.
Physical or chemical injury: Thermal burns, friction, or toxic epidermal necrolysis cause separation of the epidermis and blister formation.
Metabolic or enzymatic disorders: Porphyria cutanea tarda leads to photosensitivity and subepidermal blistering due to abnormal porphyrin metabolism.
The fluid in vesicles may contain serum, inflammatory exudate, or blood, depending on the underlying cause.
History and Physical Examination
History
Onset, progression, distribution, and recurrence of the rash.
Presence of preceding lesions, drug history, topical agent exposure, or allergens.
Associated symptoms: pruritus, burning, pain, fever, malaise.
Family history of skin disorders or allergies.
Recent infections, insect bites, or exposures.
Physical Examination
Assess skin type (dry, oily, moist) and lesion characteristics: location, color, size, shape, and distribution.
Evaluate for crusts, scales, scars, macules, papules, or wheals.
Palpate vesicles/bullae for tense vs. flaccid consistency.
Check for Nikolsky’s sign: epidermal separation upon gentle lateral pressure.
Medical causes
Cause | Pathophysiology | Key Findings |
Burns (second degree) | Thermal injury → epidermal and dermal damage → fluid accumulation | Vesicles/bullae, erythema, swelling, pain, moist skin |
Contact dermatitis | Type IV hypersensitivity reaction → epidermal inflammation | Small vesicles with erythema, edema, oozing, scaling, severe pruritus |
Dermatitis herpetiformis | IgA-mediated deposition in dermal papillae → vesicles | Symmetric vesicular/papular rash on extensor surfaces, buttocks, shoulders; severe pruritus, burning |
Nummular dermatitis | Eczematous inflammation → vesicle formation | Coin-shaped lesions, pruritic, crusting, often on limbs and trunk |
Erythema multiforme | T-cell mediated hypersensitivity reaction to infection/drugs | Symmetric macules, papules, vesicles; mucosal involvement with painful crusts |
Herpes simplex virus | Viral cytopathic effect on keratinocytes | Groups of vesicles on erythematous base, lips, genitalia; preceded by tingling/itching; painful ulcers |
Herpes zoster | Reactivation of VZV in dorsal root ganglion → dermatomal spread | Vesicular rash along dermatome, unilateral pain, fever, malaise, pruritus |
Insect bites | Local immune response to saliva/toxins | Vesicles on red papules, may become hemorrhagic |
Pemphigoid (bullous) | Autoantibody attack on hemidesmosomes → subepidermal blisters | Large tense bullae on erythematous base; generalized pruritus |
Pompholyx (dyshidrosis) | Idiopathic or eczematous reaction | Symmetrical vesicles on palms/soles; pruritic, may become pustular |
Porphyria cutanea tarda | Porphyrin accumulation → photosensitivity → subepidermal blistering | Bullae on sun-exposed areas, hyper/hypopigmentation, hypertrichosis, fragile skin |
Scabies | Mite burrows → vesicular inflammation | Small vesicles at burrow ends, intense nocturnal pruritus; webs, wrists, axilla, genitals |
Smallpox (variola major) | Viral cytopathic effect → synchronous vesicles → pustules | Fever, malaise, maculopapular → vesicular → pustular lesions; crusting → pitted scars |
Tinea pedis | Fungal infection → keratinocyte inflammation | Vesicles between toes, scaling, pruritus, pain on walking |
Toxic epidermal necrolysis | Drug-induced immune reaction → widespread epidermal necrosis | Flaccid bullae, widespread denudation, burning, fever, malaise, systemic complications |
Special considerations
Monitor for fluid and electrolyte loss in extensive eruptions; IV fluids may be required.
Maintain a warm, draft-free environment.
Monitor temperature due to increased perfusion and hyperthermia risk.
Obtain cultures and apply infection control precautions.
Use topical corticosteroids or antimicrobials as indicated.
Be aware of drug-induced toxic epidermal necrolysis, which can be life-threatening.
Patient counseling
Hand hygiene and avoiding lesion contact are critical.
Use tepid baths or cold compresses to relieve pruritus.
Adherence to prescribed therapy is essential to prevent secondary infection.
Pediatric pointers
Common causes: staphylococcal infections, varicella, hand-foot-and-mouth disease, contact dermatitis, miliaria rubra.
Severe neonatal vesicular rashes may indicate staphylococcal scalded skin syndrome.
References
Wolff K, Johnson RA. Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology. 6th ed. New York (NY): McGraw Hill Medical; 2009.
Buttaro TM, Tybulski J, Bailey PP, Sandberg-Cook J. Primary Care: A Collaborative Practice. St. Louis (MO): Mosby Elsevier; 2008. p. 551-4.
Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 6th ed. Philadelphia (PA): Elsevier; 2016.
Bolognia JL, Schaffer JV, Cerroni L. Dermatology. 4th ed. Elsevier; 2018.
James WD, Berger TG, Elston DM. Andrews’ Diseases of the Skin: Clinical Dermatology. 13th ed. Philadelphia (PA): Elsevier; 2019.
Fenske NA, Lober CW. Vesiculobullous Disorders. Lancet. 2007;370:1842-54.
Roujeau JC, Stern RS. Severe adverse cutaneous reactions to drugs. N Engl J Med. 1994;331:1272-85.
Goldsmith LA, Katz SI, Gilchrest BA, et al., editors. Fitzpatrick’s Dermatology in General Medicine. 9th ed. New York (NY): McGraw Hill; 2019.
Hengge UR, Schaller M, Goos M, et al. Management of vesicular and bullous dermatoses. J Am Acad Dermatol. 2006;54:2-21.
Kirsner RS, Rodriguez AR. Vesicular skin eruptions. Dermatol Clin. 2013;31:1-15.
Vassallo C, Leung AKC, Davies HD. Pediatric vesicular rashes. Paediatr Child Health. 2017;22:41-7.
Harrist TJ. Hand-foot-and-mouth disease, varicella, and other pediatric vesicular rashes. Pediatrics. 2014;133:e1491-503.