The site of infection becomes inflamed with a pale to brownish-red and very painful tissue swelling. If you press on the swollen tissue with your fingers, you may feel gas as a crackly sensation. The edges of the infected area expand so quickly that changes can be seen over a few minutes. The involved tissue may be completely destroyed.

Symptoms include:

• Air under the skin (subcutaneous emphysema)
• Blisters filled with brown-red fluid
• Drainage from the tissues, foul-smelling brown-red or bloody fluid (serosanguineous discharge)
• Increased heart rate (tachycardia)
• Moderate to high fever
• Moderate to severe pain around a skin injury
• Pale skin color, later becoming dusky and changing to dark red or purple
• Progressive swelling around a skin injury
• Sweating
• Vesicle formation, combining into large blisters
• Yellow color to the skin (jaundice)

Note: Symptoms usually begin suddenly and quickly worsen.

If the condition is not treated, the person can develop shock with decreased blood pressure (hypotension), kidney failure, coma, and finally death.

The person may be in shock. A health care professional might feel air in the tissues (crepitus).

• Anaerobic tissue and fluid cultures may reveal Clostridium species.
• Blood culture may grow the bacteria causing the infection.
• Gram stain of fluid from the infected area may show gram-positive rods (Clostridium species) or other bacterial types.
• X-ray, CT scan, or MRI of the area may show gas in the tissues.