Erythema is a redness of the skin, while cellulitis is a bacterial infection causing inflammation of the skin and underlying tissues, often characterized by erythema. Erythema is a symptom, whereas cellulitis is a specific condition causing that symptom.
To further clarify, here's a breakdown:
Erythema
- Definition: Simply put, erythema is redness of the skin caused by increased blood flow to the surface. It is a sign or symptom, not a disease itself.
- Causes: Erythema can result from various factors, including:
- Inflammation
- Infection
- Allergic reactions
- Sunburn
- Certain medications
- Appearance: Reddened skin. The appearance can vary from mild pinkness to deep red.
Cellulitis
- Definition: A bacterial skin infection affecting the deeper layers of the skin and subcutaneous tissues.
- Causes: Usually caused by bacteria, most commonly Staphylococcus and Streptococcus. Bacteria enter through breaks in the skin (cuts, insect bites, surgical wounds, etc.).
- Appearance: While erythema (redness) is a key feature, cellulitis also presents with:
- Pain
- Swelling
- Warmth to the touch
- Sometimes blisters or skin dimpling
- Less well-defined borders than other conditions like erysipelas
- Complications: Can become serious if left untreated, potentially leading to sepsis.
Key Differences Summarized:
Feature | Erythema | Cellulitis |
---|---|---|
Definition | Skin redness; a symptom. | Bacterial infection of the skin and subcutaneous tissue; a disease. |
Cause | Various factors (inflammation, allergy, etc.) | Bacteria (usually Staphylococcus or Streptococcus). |
Symptoms | Redness only. | Redness, pain, swelling, warmth, possible blisters, fever. |
Treatment | Depends on the underlying cause. | Antibiotics. |
In essence, seeing erythema doesn't automatically mean someone has cellulitis. Erythema is a symptom that needs further investigation to determine the underlying cause, which could be cellulitis or something else entirely.