• moderate to severe pain around a skin injury
• progressive swelling around a skin injury
• moderate to high fever
• skin color initially pale, later dusky progressing to dark red or purple
• vesicle (blister) formation, coalescent (combine into large blisters)
• blisters filled with brown-red fluid
• drainage from the tissues, foul-smelling brown-red or bloody fluid (serosanguineous discharge)
• increased heart rate (tachycardia)
• sweating
• subcutaneous emphysema (air under the skin)

Note: Symptoms usually begin suddenly and rapidly worsen.

Shock may be present, as evidenced by general pallor, cold extremities, low blood pressure, and rapid heart rate. Air in the tissues (crepitus) may be felt. Infection involving the entire body (systemic toxicity or sepsis) may develop. Yellow skin color associated with the excessive breakdown of blood cells (jaundice) is possible.

• a Gram stain of fluid from the infected area may shows Gram-positive rods and spore formation or other bacterial types
• a culture may grow the bacteria causing the infection
• blood cultures may grow the infecting bacteria
• an anaerobic tissue and/or fluid culture may reveal Clostridium species.
• an X-ray, CT scan, or MRI of the area may show gas in the tissues.