MMRSA Guide
Microscopic illustration of MRSA (Staphylococcus aureus) bacteria
Reference · Staph infection · Appearance

What does a staph infection look like?

Nearly always a red, warm, painful lump that fills with pus — and nearly always growing faster than an ordinary spot. Here is what each form looks like, what people commonly mistake it for, and when the appearance means urgent care.

Written by David Roberts, editor · Updated

Checked against current CDC and IDSA guidance. Not medically reviewed. How we source this

The short answer

A staph skin infection usually begins as a small firm red bump and becomes, over one to three days, a larger, softer, more painful lump with a pus-filled centre. The three features that matter more than colour are speed of change, pain out of proportion to size and pus. On brown and black skin redness may be hard to see at all, so judge by warmth, swelling, tightness and tenderness.

The forms staph takes on skin

FormWhat it looks likeWhere it turns up
Early bumpSmall firm red spot, tender, easily taken for a pimple or biteAnywhere skin is broken, shaved or rubbed
Pustule / folliculitisCluster of small bumps with white or yellow pus heads at hair folliclesBeard, thighs, buttocks, under arms
Boil or abscessDeep painful lump, soft in the middle, may point and drain pusButtocks, groin, armpits, back of the neck
CellulitisFlat, spreading, hot red or dusky area with a poorly defined edgeLower legs most often, also arms and face
Infected woundRed edges, swelling, cloudy discharge, stalled healingCuts, grazes, surgical incisions, drip and device sites
ImpetigoBlisters that burst and dry into honey-coloured crustsAround the nose and mouth in children

Each of these has a page of its own: boils and abscesses, folliculitis, cellulitis and skin infection overall.

Stage by stage

  • Day 0–1. A red bump the size of a spot, tender to touch. Often blamed on shaving, a bite or friction.
  • Day 1–3. It enlarges, the surrounding skin becomes warm and taut, and the middle softens as pus collects. A white or yellow head may appear.
  • Day 3–5. Either it drains — spontaneously or through a clinician's incision — and pain drops sharply, or the redness begins spreading outwards into cellulitis.
  • After drainage. A cavity that discharges for a few days, then fills in. Full healing takes one to three weeks and can leave a mark.

The equivalent progression for resistant strains, with the same timeline, is on what does MRSA look like. Appearance alone cannot tell MRSA from ordinary staph — only a laboratory culture can.

What it is not

  • A pimple — smaller, settles in days, not increasingly painful. Full comparison
  • An insect or spider bite — itchy rather than throbbing, and does not usually grow.
  • A sebaceous cyst — soft, slow, painless, present for months.
  • An ingrown hair — a single hair visible under the surface, minimal surrounding redness.
  • Hidradenitis suppurativa — recurrent lumps and tunnels in the armpits and groin, an inflammatory condition rather than a simple infection.
  • Shingles or contact dermatitis — a band or patch of rash, not a pus-filled lump. Rash look-alikes

Appearances that need same-day care

  • Redness spreading visibly by the hour, or red streaks running away from the lesion
  • Fever or chills with any skin lesion
  • Skin turning dusky, purple, grey or blistering, or pain far beyond how the skin looks
  • A lesion on the face near the eye, or over a joint or implant
  • Widespread blistering and peeling in a baby or child — see scalded skin syndrome
  • Feeling profoundly unwell, confused or breathless — see staph and MRSA sepsis

Never squeeze a lesion to force it open: it pushes bacteria deeper. Cover it, keep hands clean, and get it looked at. Treatment options are on antibiotics for a staph skin infection.

Frequently asked questions

What does a staph infection look like on the skin?
Most often a single red, swollen, warm and tender lump that grows over a day or two and develops a yellow or white pus-filled centre — a boil or abscess. It can also look like small pus-topped bumps around hair follicles, honey-crusted sores around the nose and mouth in children, a flat spreading hot red patch (cellulitis), or a cut that turns red, weeps and stops healing.
What does a staph infection look like when it starts?
Usually a small firm red bump, often mistaken for a spot or an insect bite. Within 24 to 72 hours it typically becomes larger, more painful, softer in the middle, and may point with a visible head of pus. Rapid change over hours rather than days is the feature that separates it from an ordinary pimple.
How can I tell a staph infection from a spider bite?
Most lesions people bring in as spider bites are staph abscesses. A staph lesion grows, becomes more painful and often drains pus; a genuine bite tends to itch, stays roughly the same size, and settles over a few days. If it is getting bigger and hurting more, treat it as an infection.
Is a staph infection painful?
Yes, typically. Pain and tenderness out of proportion to the size of the lesion is one of the more reliable signs, because the pressure of pus in the tissue is what hurts. Painless lumps are more often cysts, lipomas or blocked follicles.
What colour is a staph infection?
The skin around it is red or, on darker skin, deeper brown, purple or simply shinier and warmer than the skin nearby. The centre is yellow, cream or white where pus has collected, and there may be a honey-coloured crust if a sore has burst. Redness can be much harder to see on brown and black skin, so warmth, swelling, tightness and pain matter more.
What does an infected wound look like?
Increasing redness around the edges rather than fading, new swelling, warmth, cloudy or yellow-green discharge, an unpleasant smell, fresh pain after day two or three, and healing that stalls or reverses. Fever alongside any of these needs same-day attention.
Does a staph infection have a smell?
Pus from a staph lesion can smell unpleasant, particularly once a wound is involved. A strong foul smell, grey tissue, or discharge from a surgical wound should be reviewed rather than treated at home.
What does staph look like in children?
Commonly impetigo — small blisters that burst and leave golden-brown crusts around the nose and mouth. Boils, infected insect bites and infected eczema are also frequent. Widespread blistering and peeling skin in a baby or young child is a different and urgent picture: see staphylococcal scalded skin syndrome.

Symptoms hub

Overview of MRSA symptoms and day-by-day progression.

What does MRSA look like?

Bumps, boils, abscesses and cellulitis — every visual form.

MRSA rash

Does MRSA cause a rash? Look-alikes and how to tell them apart.

MRSA in the nose

Nasal carriage vs infection, swab testing and mupirocin treatment.

MRSA skin infection

Types, diagnosis, treatment, and when skin MRSA becomes dangerous.

MRSA boil

Deep, painful, pus-filled lumps and how they are drained.

MRSA cellulitis

Spreading deeper-skin infection and urgent warning signs.

MRSA folliculitis

Small pus-filled bumps around hair follicles and prevention.

MRSA pneumonia

Hospital, ventilator-associated and necrotising lung infection.

MRSA bacteremia

MRSA in the bloodstream — how it gets there and how it's treated.

MRSA sepsis

Can MRSA cause sepsis? Warning signs and survival rates.

Invasive MRSA

How MRSA reaches the bloodstream, lungs and bone.

MRSA test

PCR nasal swab, wound culture and susceptibility testing.

MSSA vs MRSA

Same bacterium, different antibiotic susceptibility.

Staph infection vs pimple

How to tell a normal pimple from a staph or MRSA skin lesion.

MRSA colonization

Carriers, nasal swabs, how long carriage lasts and when it is treated.

MRSA UTI

MRSA in the urinary tract — catheters, symptoms and treatment.

MRSA ICD-10 codes

B95.62, A49.02, Z22.322 and the sequencing rules for coders.

Scalded skin syndrome

The staph toxin illness that makes a child's skin blister and peel.

Can MRSA kill you?

Death rates by infection type, who is at risk and the warning signs.

Staph infection

Staphylococcus aureus infection overall — symptoms, spread and treatment.

Is a staph infection contagious?

How it spreads, how long for, and the school, work and sport rules.

Antibiotics for a staph skin infection

Which drugs cover staph and MRSA, course lengths and allergy options.

References
  1. CDC. Staphylococcus aureus and MRSA: signs and symptoms (2024)
  2. NHS. Staphylococcal infections (2023)
  3. Stevens D.L. et al., IDSA. Practice guidelines for the diagnosis and management of skin and soft tissue infections (2014)
  4. NHS. Impetigo (2023)
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