Erysipelas: symptoms, treatment and how it differs from cellulitis

Treatment is with antibiotics. DermNet states that oral or intravenous penicillin is the antibiotic of first choice, with other options for penicillin allergy, and that treatment usually lasts 10 to 14 days. PCDS, writing for GPs, names flucloxacillin as first line for uncomplicated cellulitis and erysipelas and notes that NICE recommends a minimum of 5 days, with some people needing longer. The exact choice and length depend on severity, allergies and local guidance, and it is a prescriber's decision.

Supportive measures are described consistently. The NHS recommends paracetamol or ibuprofen for pain, raising the affected limb when sitting or lying, moving the nearby joint to avoid stiffness, drinking plenty of fluids, and not wearing compression stockings until better. The NHS also says symptoms may worsen in the first 48 hours of antibiotics before improving, and to contact the GP if there is no improvement after 2 to 3 days.

PCDS suggests marking the edge of the redness to follow how it responds. DermNet says signs of general illness settle within a day or two, but the skin changes may take some weeks to resolve completely, and that no scarring occurs.

Erysipelas is a bacterial infection of the skin. Dermatology sources regard it as a superficial variant of cellulitis rather than an entirely separate illness: PCDS calls it "a more superficial form of cellulitis", and DermNet places it in the upper dermis with spread into the superficial lymphatic channels. NICE's clinical knowledge summary for acute cellulitis describes cellulitis as an acute bacterial infection of the dermis and subcutaneous tissue.

In everyday practice the two are often managed in much the same way, and a GP may simply record the diagnosis as cellulitis. The label matters mostly because erysipelas has a recognisable look and a particular set of usual bacteria, and because it has a reputation for coming back in the same place.

Older names include St Anthony's fire, which DermNet attributes to the intense rash. DermNet adds that erysipelas most often affects infants and older people but can occur at any age.

DermNet says the symptoms and signs are usually abrupt in onset and are often accompanied by fevers, chills and shivering. The affected skin has a very sharp, raised border, is bright red, firm and swollen, may look finely dimpled like orange peel, may blister, and in severe cases may become necrotic. When the face is involved there can be a characteristic butterfly distribution across the cheeks and bridge of the nose.

PCDS makes the comparison with cellulitis directly: the edge of the redness is better defined in erysipelas, the area is hot and tender, and swelling is common. The rash is normally on one side of the body, except on the face where both sides are occasionally affected. DermNet adds that cellulitis does not usually show such marked swelling, although pain and warmth are shared.

The NHS and NHS inform describe cellulitis as skin that is painful, hot and swollen, usually red (which can be less obvious on brown or black skin), sometimes blistered, with flu-like symptoms and swollen painful glands. In infants DermNet says erysipelas often involves the area around the umbilicus or the nappy region.

Bacteria enter through a break in the skin. PCDS says the infection usually follows a breach in the skin, although a point of entry may not be obvious, and the NHS says the break can be too small to notice. NHS inform stresses that you cannot catch cellulitis from another person because it affects deeper layers of the skin.

PCDS lists skin conditions of the lower legs such as gravitational eczema, leg ulcers, lymphoedema and tinea, previous episodes, obesity, immune compromise, chronic disease such as diabetes or chronic liver or kidney disease, and pregnancy as risk factors for cellulitis and erysipelas. DermNet adds insect bites, psoriasis, athlete's foot, surgical wounds, radiotherapy, venous disease, alcoholism and, in newborns, exposure of the umbilical cord.

The NHS advises that people at greater risk should treat athlete's foot promptly, since cracked skin between the toes is an easy way in for bacteria.

DermNet says erysipelas is usually diagnosed from the characteristic rash, often with a history of a relevant injury. Blood tests may show a raised white cell count or raised C-reactive protein, and a blood culture can identify the organism, with scans reserved for suspected deep infection. PCDS notes that skin swabs can be taken from open or weeping areas, although results are often negative.

An important part of assessment is excluding look-alikes. PCDS lists deep vein thrombosis, gravitational eczema, contact allergic dermatitis, panniculitis and the rarer eosinophilic cellulitis. It stresses that gravitational eczema on both legs is sometimes wrongly treated as cellulitis, which is nearly always one-sided and usually comes with fever, whereas eczema brings itch and non-tender redness.

Because DermNet reports recurrence in up to a third of people, prevention is a significant part of care. PCDS advises identifying and managing causes such as lower-leg skin conditions, leg ulcers and oedema, treating athlete's foot, weight control and good diabetes control. It says antibiotic prophylaxis should be offered to people who have two or more attacks of cellulitis a year, and that it may sometimes need to be long term. The NHS also says some people with recurring cellulitis are prescribed low-dose antibiotics over the long term.

Day-to-day skin care is the other half: the NHS recommends keeping skin clean and moisturised, cleaning any cuts or wounds with antiseptic cream, and wearing suitable clothing, footwear and gloves to avoid cuts and scrapes. NICE CKS also mentions emollients to prevent dry, cracked skin.

Complications are uncommon but can be serious. DermNet lists abscess, chronic leg swelling, infection at distant sites such as heart valves and joints, a kidney complication in children, and, rarely, streptococcal toxic shock. PCDS lists lymphangitis (a red line spreading from the area), deep infection and septicaemia, and separately describes necrotising fasciitis, where pain and illness seem out of proportion to what is visible on the skin.

The NHS tells people to get an urgent GP appointment or NHS 111 help for painful, hot, swollen skin, and to call 999 or go to A&E if there is a very high temperature or feeling hot, cold or shivery, fast heartbeat or breathing, purple patches, dizziness or faintness, confusion, cold clammy or pale skin, or unresponsiveness. NHS inform also lists involvement of the face or the area around the eye and a weakened immune system as reasons for emergency help. NICE CKS says people with facial cellulitis, infection near the eyes or nose, or who are very young, elderly, frail or immunocompromised may need hospital admission.

Most erysipelas is dealt with by a GP or an urgent treatment service, with antibiotics taken at home. Hospital care, sometimes with intravenous antibiotics, is for people who are unwell, very young or elderly, or whose infection is spreading despite tablets. A community or hospital team may also be involved when there is leg swelling or lymphoedema underneath.

People with repeated attacks sometimes want a dermatologist or vascular specialist to look at the underlying causes, and a private appointment can be quicker to arrange than an NHS outpatient referral. The questions covered are broadly similar either way: skin barrier problems, fungal infection of the feet, venous disease and lymphatic drainage, and whether preventive antibiotics are appropriate. Neither route changes the urgent-care advice above.