Rash, itch, infection and skin ulcers

Describe the eruption and systemic illness

Describe morphology, distribution, onset, progression, itch or pain, mucosal involvement and associated symptoms. Ask about new medicines, contacts, travel, occupational exposure and immune status. Examine beyond the presenting patch, including palms, soles, scalp and nails where relevant. Fever, hypotension, rapidly spreading pain, purpura, blistering or mucosal erosion may signal serious infection or a severe drug reaction. A darkly pigmented patient's inflammation may look different from textbook erythema; warmth, swelling, tenderness and symptoms also guide assessment.

Non-blanching rash with systemic illness needs emergency assessment for sepsis and other serious causes. A painful rapidly spreading lesion, toxicity or pain out of proportion raises necrotising infection and requires urgent surgical review, not waiting for antibiotics alone to work. New widespread skin pain, blistering and mucosal lesions after a medicine raises Stevens–Johnson syndrome/toxic epidermal necrolysis; stop suspected triggers and arrange emergency specialist care. Eosinophilia, fever and organ involvement can occur with other severe drug reactions. Record the suspected medicine and timing clearly.

Eczema, psoriasis and common infections

Eczema management combines regular emollients, suitable cleansing and topical anti-inflammatory treatment for flares. Teach quantity, site, potency and duration rather than giving an unexplained tube. Correctly used topical steroids are effective; steroid fear can lead to undertreatment. Oozing, crusting or systemic symptoms suggests infection, while painful monomorphic vesicles or punched-out erosions raises eczema herpeticum and urgent antiviral assessment. Not every flare requires oral antibiotics or allergy testing. Review sleep, school and family impact as well as the visible area.

Psoriasis produces characteristic plaques but can also affect folds, nails and joints. Ask about inflammatory joint symptoms and assess severity/function. Topical treatment, phototherapy or systemic therapy is selected according to extent and impact. Annular fungal disease may resemble eczema; steroid-only treatment can mask/worsen it. Impetigo, cellulitis and abscess require different treatment decisions. An abscess may need drainage, while bilateral chronic lower-leg redness can reflect venous dermatitis rather than bilateral bacterial cellulitis. Select antimicrobials by local guidance and risks, including water or bite exposure.

Itch and infestation

Scabies is suggested by nocturnal itch, typical sites and affected close contacts; infants, older people and immunocompromised patients can have different distributions. Treat the person and relevant close contacts in coordination, with the environmental measures in the current pathway. Itch can persist after successful treatment and does not automatically prove reinfestation. Crusted scabies is highly transmissible and needs specialist/public-health management. Ask about practical access to medication, laundry and coordinated treatment rather than blaming a family when treatment fails.

Generalised itch without a primary rash can arise from medicines, kidney or cholestatic liver disease, haematological illness or dry skin. Investigate according to history and systemic findings. Urticaria consists of transient wheals; isolated wheals differ from anaphylaxis with airway, respiratory or circulatory features. Angioedema involving the tongue or airway is an emergency. ACE-inhibitor bradykinin angioedema may lack itch/hives and does not respond like routine histamine disease. Stop the offending medicine and prioritise airway assessment.

Ulcers and wound healing

Assess an ulcer's site, depth, duration, perfusion, sensation, pressure exposure and infection. Venous ulcers often accompany oedema and skin changes near the gaiter region. Arterial ulcers, rest pain, a cold foot or tissue loss need vascular assessment. Diabetic neuropathy can conceal a deep infected wound or osteomyelitis. Compression requires an appropriate arterial assessment and is not a safe default for an ischaemic limb. Offloading and pressure redistribution matter as much as a dressing. Review nutrition, smoking, glucose, footwear and mobility.

A chronic wound that changes, bleeds, develops an unusual edge or fails to heal needs consideration of malignancy and biopsy. Odour or colonisation alone does not establish invasive infection; assess increasing pain, spreading inflammation, systemic illness and deeper structures. Use dressings suited to exudate and tissue rather than one product for every ulcer. Avoid indiscriminate superficial swabs without a clinical question. Document measurements and progress, and ensure a multidisciplinary plan addresses circulation, pressure and the underlying cause.

Applied decisions

A diabetic patient with a painless plantar wound needs depth, perfusion and infection assessment despite little discomfort. A febrile patient with rapidly spreading painful skin change needs emergency surgical review for possible necrotising disease. A child with itchy flexural eczema and no infection can receive a practical home flare plan and review. These presentations should not all receive the same antibiotic. Explain the diagnosis and treatment technique, check understanding, and provide clear escalation signs. Photographs can assist progression only with consent and approved secure record handling.

RCH eczema and RCH cellulitis and skin infection.

Review checkpoints

• Mucosal involvement with systemic illness can signal a severe drug reaction.
• A non-blanching rash with illness needs urgent assessment.
• Chronic wounds require evaluation of perfusion, pressure, neuropathy and infection.