Reviewed by The Wellness Team. Last reviewed October 2026.
A patch of skin that becomes red, hot, swollen and tender, and keeps spreading, needs prompt attention. Cellulitis is a common bacterial skin infection that responds well to antibiotics, but timing matters. Here is how to recognise it, what treatment involves and when it is urgent.
What is cellulitis
Cellulitis is a bacterial infection of the deeper layers of the skin and the tissue beneath it. It usually enters through a break in the skin, such as a cut, graze, insect bite, ulcer or cracked athlete's foot. The legs are affected most often, but it can appear anywhere, including the arms and face.
What cellulitis looks and feels like
- An area of skin that is red, hot, swollen and tender to touch
- Redness that spreads outward over hours or days
- Tight, shiny or swollen skin, sometimes with blistering
- Feeling generally unwell, with fever, shivers or aches
- Swollen glands near the affected area
Cellulitis almost always affects one side only. Symmetrical redness on both legs usually has a different cause.
Cellulitis or something else
Several conditions mimic cellulitis, including deep vein thrombosis, varicose eczema, gout and allergic reactions. The treatment for each is completely different, which is why an assessment matters before antibiotics are started. A GP can usually tell the difference from the appearance, the history and simple checks, and can arrange further tests where there is doubt.
How cellulitis is treated
NICE guidance recommends prompt antibiotic treatment, most commonly flucloxacillin, with an alternative such as clarithromycin or doxycycline for people allergic to penicillin. Elevating the limb, rest, fluids and simple pain relief support recovery. Drawing around the edge of the redness helps track whether it is still spreading.
Most people start to improve within two to three days of starting antibiotics, though the skin can take one to two weeks to settle fully. More severe infections, or cellulitis that is not responding, may need hospital treatment with intravenous antibiotics.
When cellulitis is urgent
Seek urgent medical help the same day if any of the following apply:
- Rapidly spreading redness, or redness near the eye or spreading across the face
- High fever, shivering, confusion, dizziness or a racing heartbeat
- Severe pain out of proportion to the appearance
- You have a weakened immune system, diabetes with poor control, or lymphoedema
- Blisters, skin turning dusky or black, or numbness in the area
These can signal sepsis or a deeper infection and should not wait.
When to see a GP today
Even without red flags, suspected cellulitis should be assessed promptly, ideally the same day, because early antibiotics shorten the illness and reduce complications. Drawing the line and waiting is reasonable only once a clinician has seen it and confirmed what it is.
What an online GP can do today
A video consultation lets a GP examine the affected skin, review photos, confirm the likely diagnosis and prescribe antibiotics the same day where clinically appropriate, sent electronically to your chosen pharmacy. If the picture suggests something else, or you need blood tests or hospital review, the GP will explain and arrange the right next step.
Appointments cost £59 by phone, £150 by video and £220 in person at 10 Portman Square, Marylebone, with the price confirmed before you book. Same day appointments are usually available. Message us on WhatsApp at https://wa.me/447961280835 to book.
Sources: NICE Clinical Knowledge Summaries, Cellulitis (acute); NICE guideline NG141, Cellulitis and erysipelas: antimicrobial prescribing.
Reviewed by The Wellness Team