Severe Skin and Soft Tissue Infections

Key facts

• Severe skin and soft tissue infections (SSTIs) go beyond ordinary cuts or superficial rashes, penetrating deeper layers of skin, fat, or muscle and worsening quickly without treatment.
• The group includes cellulitis that spreads despite initial care, abscesses that need drainage, and more serious conditions such as necrotising fasciitis.
• Redness spreading beyond a wound edge, tight and warm swelling, blisters, or dark discolouration are warning signs that need urgent attention.
• Treatment nearly always includes antibiotics, such as clindamycin, and severe cases often also need surgical drainage or debridement.

Warning signs that demand prompt attention

Redness that spreads beyond a wound edge, skin that feels warm and tightly swollen, or the appearance of blisters or dark discolouration are all reasons to seek care urgently. Fever, chills, or a racing heartbeat alongside a skin wound suggest the infection has begun affecting the whole body rather than staying local, and that combination should prompt same-day medical assessment.

The role of antibiotics in treatment

Severe SSTIs almost always require antibiotics. The choice depends on which bacteria are likely responsible: many deep infections involve anaerobic organisms or bacteria such as MRSA alongside the more common streptococci. Clindamycin is active against a broad range of these pathogens and is frequently used for skin and soft tissue infections where anaerobic cover or MRSA activity is needed. It works by blocking bacterial protein synthesis, which stops the infection from multiplying while the immune system and any drainage clear the rest.

Surgical drainage of abscesses or debridement of dead tissue is often necessary alongside antibiotics; medicine alone cannot clear pockets of pus or tissue that has already died, and delaying a needed procedure can let the infection spread.

When to see a doctor

Get same-day medical care for a skin infection that is spreading rapidly, causing a high fever, or affecting skin that looks dark or feels numb: these can signal a deeper infection that needs urgent treatment rather than a wait-and-see approach.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.