A flare that suddenly stops behaving like a flare is the situation this page is about. The first 48 hours of a flare carries the response protocol and names the warning signs in a paragraph. This is the long version: how to separate a bacterial infection from eczema herpeticum without a photograph to compare against, what each is triaged as, what a swab and a course of antibiotics are for, and why the emollient tub matters afterwards.
The NHS puts the trigger for urgent contact in four lines. Ask for an urgent GP appointment or get help from NHS 111 if "it's blistered, crusty, leaking fluid or has spots filled with pus", if "it's painful, swollen or feels warm", if "it suddenly gets worse or gets bigger", or if "you have a high temperature or feel generally unwell". The page routes you to 111 online for anyone aged 5 and over, or a phone call to 111 for children under 5 (NHS, Atopic eczema). Nothing below replaces that step, and no self-managed change to a prescribed treatment is part of it.
The bacterial signs, as the guidance words them
NICE's guideline for children under 12, CG57, lists what to teach families to recognise as bacterial infection with staphylococcus or streptococcus: "weeping, pustules, crusts, eczema failing to respond to therapy, rapidly worsening eczema, fever, malaise" (CG57, recommendation 1.5.1.36).
Read that list again and notice what is not in it. There is no colour, no shade, no "redness". Every item is either a texture, a discharge, a rate of change or something happening to the whole person. That is what makes it usable without a photograph and on any skin tone: you are checking whether the surface has started producing fluid, pus or crust, whether the area is moving faster than a flare normally moves, and whether you feel ill in yourself.
The item people miss is the fourth one. Eczema that fails to respond to therapy counts as a sign in its own right. If a topical steroid course that has reliably settled this patch before is doing nothing this time, that failure is a sign in its own right, and one that belongs on the same-day list above.
Eczema herpeticum: the erosions are the tell
Eczema herpeticum is herpes simplex spreading through eczematous skin. The British Association of Dermatologists describes it as "a potentially serious viral infection which can spread to affect large areas of the skin", starting as groups of small blisters that can keep spreading over seven to ten days, and often accompanied by "a high temperature with shivering, swollen lymph glands, headache, feeling tired (malaise), sore or gritty eyes if eye involvement occurs" (BAD, Eczema herpeticum).
The precise part is what the blisters leave behind. CG57 tells families to look for areas of rapidly worsening, painful eczema, clustered blisters that look like early-stage cold sores, and "punched-out erosions (circular, depressed, ulcerated lesions), usually 1 mm to 3 mm, that are uniform in appearance (these may combine to form larger areas of erosion with crusting)", with possible fever, lethargy or distress (1.5.1.42).
Two words there carry the diagnosis. Uniform: the lesions match each other in size and shape, because they came from one crop of blisters rather than from scratching. And small: 1 mm to 3 mm, the size of a pinhead. Infected eczema produces crust and pus over an irregular area that follows wherever the skin was already broken. Eczema herpeticum produces a field of identical small round craters, with pain out of proportion to how the patch looks. NHS Highland's antimicrobial guidance uses the same shorthand for adults: "sudden onset of painful, uniform grouped vesicles/erosions".
How urgent, and to whom
This is the part where the two diagnoses separate. Bacterial infection is an urgent GP appointment or 111, on the NHS wording above. Suspected eczema herpeticum is faster than that.
CG57 is unambiguous for children: "If eczema herpeticum (widespread herpes simplex) is suspected in a child with atopic eczema, immediately start treatment with systemic aciclovir and refer the child for same-day specialist dermatological advice" (1.5.1.40). Where it involves the skin around the eyes, the same recommendation set adds same-day ophthalmological advice alongside the dermatological referral (1.5.1.41), which is why "sore or gritty eyes" is on the BAD symptom list rather than filed as a separate complaint.
For adults, NHS Highland's guidance treats suspected eczema herpeticum as grounds to prescribe systemic aciclovir and refer as a medical emergency. BAD says to get early treatment from a doctor, and to "seek urgent help with the out of hours team or A&E" if things worsen rapidly. Treatment is usually antiviral tablets or syrup, with hospital admission for intravenous treatment in severe cases.
If any of these routes ends in a referral, what a dermatologist referral involves covers what happens next.
What a swab settles, and what it does not
A swab feels like the definitive test. It is not treated as one at first contact. NHS Highland's guidance states: "Do not routinely take a skin swab for microbiological testing in people with secondary bacterial infection of eczema at the initial presentation." NHS Forth Valley's primary care guidance draws the same line and names the exception, advising against a swab unless there is a history of frequent recurrence of infected eczema.
A swab answers a different question from the one being asked. It reports what is growing on the skin surface, while the decision turns on whether the skin is infected, which is read from the signs above and from how you are in yourself. Where a swab earns its place is the repeat case, where knowing which organism keeps returning changes the plan.
What antibiotics are actually for
The default is narrower than most people expect. NHS Highland's guidance: "In people who are not systemically unwell, do not routinely offer either a topical or oral antibiotic for secondary bacterial infection of eczema." NHS Forth Valley's formulary splits the cases that do warrant treatment: topical fusidic acid where infection is localised and the person is systemically well, an oral antibiotic where it is more widespread or the person is systemically unwell. Which of those applies, and whether either applies, is the prescriber's call at the appointment.
CG57's own recommendations on managing bacterial infection were withdrawn in March 2021 and replaced by a separate NICE antimicrobial prescribing guideline, NG190, covering secondary bacterial infection of eczema and other skin conditions. What CG57 retains is the safety net for when antibiotics do not work: "Consider herpes simplex (cold sore) infection if a child's infected atopic eczema fails to respond to treatment with antibiotics and an appropriate topical corticosteroid" (1.5.1.38). A course that changes nothing is a reason to go back, not a reason to finish and hope.
The tub in the bathroom
One instruction survives the episode. CG57 recommendation 1.5.1.37 tells families to obtain new supplies of their topical eczema medications after treatment for infected eczema, "because their medications can become contaminated and act as a source of infection". Fingers go into a tub, then onto broken skin, then back into the tub. The NHS makes the same point from the other direction in its everyday advice: "do not share your emollients with anyone else".
Occlusion is the other thing that changes while skin is infected. Wet wrapping is ruled out on infected skin in the guidance that covers it, and that post sets out the boundaries NICE puts around the technique.
Bleach baths: what the meta-analysis found
Bleach baths come up constantly in this context, and the pooled evidence is more equivocal than the enthusiasm suggests. Chopra and colleagues systematically reviewed five studies of bleach baths in atopic dermatitis (Chopra et al, 2017). Four reported significantly decreased severity in patients treated with bleach at at least one timepoint. But of the four studies that compared bleach with plain water baths, only two found significantly greater decreases with bleach, one found greater decreases with water, and one found no significant difference. In pooled analysis at four weeks against baseline there was no significant difference between bleach and water baths for the Eczema Area and Severity Index (P = .16) or body surface area (P = .36).
The authors' conclusion is the sentence worth carrying: "Although bleach baths are effective in decreasing AD severity, they do not appear to be more effective than water baths alone." The comparison arm is the whole finding. That is a question to put to a clinician who knows your skin, not something to start from a reading of this page.
References
- NHS. Atopic eczema. https://www.nhs.uk/conditions/atopic-eczema/
- National Institute for Health and Care Excellence. Atopic eczema in under 12s: diagnosis and management. NICE Clinical Guideline CG57. https://www.ncbi.nlm.nih.gov/books/NBK571009/
- British Association of Dermatologists. Eczema herpeticum, patient information leaflet. https://www.bad.org.uk/pils/eczema-herpeticum/
- NHS Highland. Eczema (antimicrobial), adult therapeutic guidelines. https://www.rightdecisions.scot.nhs.uk/tam-treatments-and-medicines-nhs-highland/adult-therapeutic-guidelines/antimicrobial-guidance/skin-soft-tissue-antimicrobial/eczema-antimicrobial/
- NHS Forth Valley. Infected eczema, primary care antimicrobial guidance. https://www.rightdecisions.scot.nhs.uk/antimicrobial-prescribing-nhs-forth-valley/primary-care-guidance/skin-infections/infected-eczema/
- Chopra R, Vakharia PP, Sacotte R, Silverberg JI. Efficacy of bleach baths in reducing severity of atopic dermatitis: a systematic review and meta-analysis. Annals of Allergy, Asthma and Immunology, 2017, 119:435-440. https://doi.org/10.1016/j.anai.2017.08.289