For guidance on human and animal bites, see here.

The information below is based on NICE NG141 Cellulitis and erysipelas: antimicrobial prescribing.

To ensure appropriate treatment, exclude other causes of skin redness such as an inflammatory reaction to an immunisation or an insect bite, a human or animal bite, or a non-infectious cause such as chronic venous insufficiency. Consider whether referral is required (see Reassessment and referral below).

Consider taking a swab for microbiological testing only if the skin is broken and:

• there is a penetrating injury or
• there has been exposure to water-borne organisms or
• the infection was acquired outside the UK or
• if not responding to antibiotics at reassessment.

Before treating, consider drawing around the extent of the infection with a single-use surgical marker pen to monitor progress (be aware that redness may be less visible on darker skin tones).

When prescribing antibiotics, give advice regarding:

• possible adverse effects
• the skin taking time to return to normal after finishing the antibiotics
• when to seek medical help (see Reassessment and referral below).

Note: Standard course lengths are given below. A 5- to 7-day course is sufficient for most people and will help reduce the risk of antimicrobial resistance and minimise the risk of side effects. A longer course (up to 14 days in total) may be needed based on clinical assessment; however, skin does take some time to return to normal, and full resolution of symptoms at 5 to 7 days is not expected.

For severe infections, refer or seek specialist advice.

Oral antimicrobials for adults ≥18 years

For severe infections, refer or seek specialist advice.

For infection around the eyes or nose, refer to the relevant subsection below.

Flucloxacillin

• 500mg to 1g four times a day for 5 to 7 days
• Note: although dose of 1g four times a day is off-label, it is routinely recommended by NICE and supported by local specialists
• See section 5.1.1 Penicillins.

If penicillin allergy or flucloxacillin is unsuitable:

Clarithromycin

• Erythromycin (below) is preferred if a macrolide is needed in pregnancy
• 500mg twice a day for 5 to 7 days
• See section 5.1.5 Macrolides.

OR

Erythromycin

• Suitable for use in pregnancy
• 500mg four times a day for 5 to 7 days
• See section 5.1.5 Macrolides.

OR

Doxycycline

• 200mg single dose stat then 100mg once a day for a total of 5 to 7 days
• See section 5.1.3 Tetracyclines.

Infection near the eyes or nose

Infection around the eyes or nose (the triangle from the bridge of the nose to the corners of the mouth, or immediately around the eyes including periorbital cellulitis) is of more concern because of risk of a serious intracranial complication.

Consider referral or seeking specialist advice.

Have a low threshold for referral if signs and symptoms suggesting orbital involvement are present, for example:

• blurring / reduced visual acuity or colour perception
• ophthalmoplegia (restricted eye movements, double vision)
• proptosis
• pupillary dysfunction (relative afferent pupil defect)
• sclera changes.

Co-amoxiclav

• 500mg/125mg three times a day for 7 days
• See section 5.1.1 Penicillins.

If penicillin allergy or co-amoxiclav is unsuitable:

Clarithromycin

• 500mg twice a day for 7 days

PLUS

Metronidazole

• 400mg three times a day for 7 days

See sections 5.1.5 Macrolides and 5.1.11 Metronidazole and tinidazole.

Oral antimicrobials for children & young people <18 years

For children under 1 month seek specialist advice.

For severe infections, refer or seek specialist advice.

For infection around the eyes or nose, refer to the relevant subsection below.

Flucloxacillin

• Children 1 month to 17 years of age (doses given four times a day for 5 to 7 days):
  • 1 month to 1 year: 62.5mg to 125mg
  • 2 years to 9 years: 125mg to 250mg
  • 10 years to 17 years: 250mg to 500mg
• See section 5.1.1 Penicillins.

If flucloxacillin is unsuitable:

Co-amoxiclav

• Not for use in penicillin allergy
• Children 1 month to 17 years of age (doses given three times a day for 5 to 7 days):
  • 1 month to 11 months: 0.25ml/kg (125mg/31mg/5ml suspension)
  • 1 year to 5 years: 0.25ml/kg or 5ml (125mg/31mg/5ml suspension)
  • 6 years to 11 years: 0.15ml/kg or 5ml (250mg/62mg/5ml suspension)
  • 12 years to 17 years: 250mg/125mg or 500mg/125mg
• See section 5.1.1 Penicillins.

If penicillin allergy or flucloxacillin is unsuitable:

Clarithromycin

• Erythromycin (below) is preferred if a macrolide is needed in pregnancy
• Children 12 years to 17 years of age:
  • 250mg to 500mg twice a day for 5 to 7 days
• Children 1 month to 11 years of age (doses given twice a day for 5 to 7 days):
  • Under 8kg: 7.5mg/kg
  • 8kg to 11kg: 62.5mg
  • 12kg to 19kg: 125mg
  • 20kg to 29kg: 187.5mg
  • 30kg to 40kg: 250mg
• See section 5.1.5 Macrolides.

OR

Erythromycin

• Suitable for use in pregnancy
• Children 8 years to 17 years of age:
  • 250mg to 500mg four times a day for 5 to 7 days
• See section 5.1.5 Macrolides.

Infection near the eyes or nose

Infection around the eyes or nose (the triangle from the bridge of the nose to the corners of the mouth, or immediately around the eyes including periorbital cellulitis) is of more concern because of risk of a serious intracranial complication.

Consider referral or seeking specialist advice.

Have a low threshold for referral if signs and symptoms suggesting orbital involvement are present, for example:

• blurring / reduced visual acuity or colour perception
• ophthalmoplegia (restricted eye movements, double vision)
• proptosis
• pupillary dysfunction (relative afferent pupil defect)
• sclera changes.

Co-amoxiclav

• Children 1 month to 17 years of age (doses given three times a day for 7 days):
  • 1 month to 11 months: 0.25ml/kg (125mg/31mg/5ml suspension)
  • 1 year to 5 years: 0.25ml/kg or 5ml (125mg/31mg/5ml suspension)
  • 6 years to 11 years: 0.15ml/kg or 5ml (250mg/62mg/5ml suspension)
  • 12 years to 17 years: 250mg/125mg or 500mg/125mg
• See section 5.1.1 Penicillins.

If penicillin allergy or co-amoxiclav is unsuitable:

Clarithromycin

• Children 12 years to 17 years of age:
  • 250mg to 500mg twice a day for 7 days
• Children 1 month to 11 years of age (doses given twice a day for 7 days):
  • Under 8kg: 7.5mg/kg
  • 8kg to 11kg: 62.5mg
  • 12kg to 19kg: 125mg
  • 20kg to 29kg: 187.5mg
  • 30kg to 40kg: 250mg

PLUS (if anaerobes suspected)

Metronidazole

• Children 12 years to 17 years of age:
  • 400mg three times a day for 7 days
• Children 1 month to 11 years of age (doses given over 7 days):
  • 1 month: 7.5mg/kg twice a day
  • 2 months to 11 years: 7.5mg/kg three times a day (maximum per dose 400mg)

See section 5.1.5 Macrolides and 5.1.11 Metronidazole and tinidazole.

Reassessment and referral

Reassessment

Reassess if symptoms worsen rapidly or significantly at any time, do not start to improve within 2 to 3 days, or the person:

• becomes systemically very unwell or
• has severe pain out of proportion to the infection or
• has redness or swelling spreading beyond the initial presentation.

Consider taking a swab for microbiological testing if the skin is broken and this has not been done already (see introduction).

If a swab has been sent to microbiological testing:

• review the choice of antibiotic(s) when results are available and
• change the antibiotic(s) according to the results as appropriate.

Referral

Refer people to hospital if they have any symptoms or signs suggesting a more serious illness or condition, such as orbital cellulitis, osteomyelitis, septic arthritis, necrotising fasciitis or sepsis.

Consider referral or seek specialist advice if the person:

• is severely unwell or
• has infection near the eyes or nose or
• could have uncommon pathogens (after a penetrating injury, exposure to water-borne organisms, or an infection acquired outside the UK) or
• has a past history of MRSA or
• has spreading infection that is not responding to oral antibiotics or
• has lymphangitis or
• cannot take oral antibiotics.