Health education · SkinSkin health
Cellulitis: recognizing a skin infection and preventing complications
An area of skin becomes red, warm, swollen and painful? It may be cellulitis, a skin infection caused by bacteria that is usually treated with antibiotics.1,3
Seek care promptly if you suspect this infection. Rapid spread, very severe pain or a decline in your general condition need urgent assessment.1
A red streak running up the limb (lymphangitis) strongly suggests infection.1 The skin’s appearance, pain and how it evolves must be considered together.
Entry points
How do bacteria get into the skin?
Skin is normally a protective barrier. An opening, sometimes tiny or impossible to find, can let bacteria in.
A red or swollen bite isn’t automatically infected: a reaction to the bite is one of the problems that can look like cellulitis.1
Cellulitis or abscess
Cellulitis or abscess: what’s the difference?
| Problem | Main features |
|---|---|
| Cellulitis | Infection that spreads through the skin and the tissue beneath it, without a pocket of pus. |
| Skin abscess | A well-defined collection of pus.2 See the Skin infections and abscesses page. |
| Cellulitis with abscess | A pocket of pus surrounded by infection of nearby tissue.1 |
Treatment of an abscess relies mainly on draining the pus. After draining a small abscess without much cellulitis around it, antibiotics are rarely needed.1,2
Diagnosis
How is cellulitis diagnosed?
Diagnosis is based on symptoms and a skin exam. The professional also looks for the entry point, a pocket of pus, how deep the infection is and signs of severity.1
Blood tests and cultures aren’t done routinely. A culture is mainly useful if there is pus or drainage, or in certain situations, such as a deep bite.1,5
Several problems can look like cellulitis, such as eczema, contact dermatitis, an insect bite, shingles, phlebitis or stasis dermatitis of both legs.1
Treatment
How is cellulitis treated?
Supportive care
- keep taking the antibiotic exactly as prescribed, without stopping it on your own;4
- raise the affected limb several times a day to reduce swelling;1,3,4
- use compression only as directed by your care team;1,4
- for pain, acetaminophen is suggested in adults; ask before taking an anti-inflammatory, which can mask signs of inflammation;1
- keep the area clean and dry, with no cream or ointment unless advised;3
- bring unused antibiotics back to the pharmacy.1
Recovery
How soon should it improve?
The skin doesn’t return to normal right away. Slightly more inflammation in the first 24 to 48 hours is common, as long as your general condition, pain and fever are improving.1,3
See a professional again if, 48 hours after starting the antibiotic, your general condition, pain or fever aren’t improving, or if the redness spreads past the line drawn.1 Also seek care if fever lasts 72 hours after starting treatment, or if vomiting keeps you from taking the antibiotic.3 Don’t wait if things get worse quickly.
Swelling can last weeks, sometimes months, after the infection has cleared, and skin colour may take time to return to normal.1,4
Tracing the edge of the redness with a pen or taking photos helps track changes.1
Emergency
When to go to the emergency department?
Some signs can point to a deep infection, such as necrotizing fasciitis, or a complication.1,2
Go to the emergency department right away if you have:1,3
- extreme pain, or pain out of proportion to how the skin looks, even at rest;
- very rapid spread of the redness;
- blood-filled blisters, skin turning black or grey, or crackling under the skin;
- a major decline in general condition, drowsiness or dizziness that keeps you from walking;
- infection around the eye with pain when moving the eyes, trouble opening the eye or a change in vision;
- infection of the face or neck with difficulty swallowing or breathing.
Call 9-1-1 if you have difficulty breathing, confusion or loss of consciousness.
Complications and contagion
Complications and contagion
What complications can occur?
Complications are uncommon but can be serious: bloodstream infection, deep tissue infection (necrotizing fasciitis), or infection of a bone or joint.5
Prompt care and monitoring help identify situations that need more intensive treatment.
Prevention
How can you prevent recurrences?
Prevention is mainly about protecting the skin barrier.1,2,5
A few habits help:4
- clean cuts and scrapes with soap and water, and change wet or dirty bandages;
- moisturize dry skin with an unscented product, but not between the toes;
- check your hands and feet every day for sores, cracks or red areas;
- trim nails carefully and don’t scratch wounds or pick at scabs;
- treat athlete’s foot, eczema and persistent swelling;1,5
- after a wound, check that your tetanus vaccine is up to date.1
If infections keep coming back, an assessment can look for the factors behind them and adjust prevention.1
When to consult at the Clinique IPS du Palais?
A nurse practitioner can assess skin redness, tell cellulitis apart from other problems, prescribe treatment, follow up within 24 to 72 hours of starting treatment and refer you to the emergency department when warning signs are present.
Extreme pain, rapid spread, blood blisters or a worsening general condition: go to the emergency department.
Sources
- Institut national d’excellence en santé et en services sociaux (INESSS). Cellulite infectieuse chez l’adulte (in French), optimal use guide. Published July 24, 2026, revised October 13, 2026, accessed October 30, 2026. inesss.qc.ca
- Penner J, Fanella S, Canadian Paediatric Society. Management of bacterial skin and soft tissue infections in children. May 26, 2026, accessed October 30, 2026. cps.ca
- CHU de Québec–Université Laval. Cellulite infectieuse (in French). Update date not stated, accessed October 30, 2026. chudequebec.ca
- Nova Scotia Health. Cellulitis – Patient Oriented Discharge Summary. December 2025, accessed October 30, 2026. nshealth.ca
- Centers for Disease Control and Prevention. Clinical Guidance for Group A Streptococcal Cellulitis. Updated August 5, 2025, accessed October 30, 2026. cdc.gov
This sheet provides general information and does not replace an assessment or personalized treatment. Published October 30, 2026.