Wound Discharge: Colors, Causes and When to Worry

What wound discharge is made of

When skin is damaged, nearby blood vessels become leaky so that immune cells and healing proteins can reach the area. The fluid that escapes is called exudate. It keeps the wound bed moist, which helps new cells grow, and carries away debris. The color, thickness, smell and amount tell clinicians how the wound is doing.

Wound discharge colors and what they mean

Open wound with black discharge

Black or very dark discharge usually comes from dead tissue or old, clotted blood. A dry black scab (eschar) can form over pressure sores and ulcers. Wet black or gray tissue with a foul smell, especially with spreading pain, swelling or blistering, can be gangrene or a necrotizing infection, which needs emergency treatment. People with diabetes or poor circulation should never ignore darkening tissue in a foot wound.

What a wound with a lot of discharge means

The amount of drainage matters as much as the color. Heavy discharge, where dressings soak through several times a day, can be caused by:

• Infection: bacteria increase inflammation and fluid. See infection of an open wound.
• Swelling (edema) of the limb: common in leg ulcers from vein disease. Fluid seeps out through the wound.
• Seroma: a pocket of fluid under a surgical wound, which may leak through the incision.
• Wound breakdown: a surgical wound that starts to separate (wound dehiscence).
• Large or deep wounds, burns and wounds with lots of dead tissue.
• Chronic wounds such as venous ulcers, which produce more exudate than acute cuts.

Heavy drainage also damages the surrounding skin, making it white, soggy and fragile (maceration), which can widen the wound.

Signs discharge is from infection

• Discharge becomes thicker, cloudy or colored after the first 2 to 3 days
• A bad smell, even after cleaning
• Increasing redness, warmth and swelling
• Pain getting worse instead of better
• Fever or chills
• The wound stops shrinking or opens up

How clinicians assess it

A nurse or doctor will look at the wound bed, edges and surrounding skin, and note the color, amount and smell of the discharge. They may take a swab to identify bacteria, mark the edge of any redness, and check blood tests if you have fever. Ultrasound can show a fluid collection or abscess under a surgical wound.

Treatment and wound care

• Clean the wound gently with clean water or saline at each dressing change.
• Choose the right dressing: absorbent foam, alginate or hydrofiber dressings for heavy drainage; thinner dressings for light drainage. A clinician can advise.
• Change dressings when they are wet through, rather than leaving soaked dressings in place.
• Protect surrounding skin with a barrier film or cream if it becomes soggy.
• Raise a swollen leg, and use compression only if advised for vein-related ulcers.
• Antibiotics are prescribed for infection. Pus collections may need draining.
• Dead tissue is removed by a clinician (debridement).

Frequently asked questions

Is it normal for a wound to have discharge?

Yes, a small amount of clear, pale yellow or light pink discharge is normal for the first few days. It is part of healing. Thick, cloudy, colored or smelly discharge, or increasing amounts after day 3, is not normal and should be checked.

What does yellow discharge from a wound mean?

Thin, pale yellow, watery fluid is usually serous fluid and normal. Thick, opaque yellow discharge that looks like custard, especially with a smell or redness, is pus and suggests infection. A yellow film stuck to the wound bed (slough) is dead tissue, not discharge.

What does green wound discharge mean?

Green discharge almost always means infection. A blue-green color with a sweet smell often points to Pseudomonas bacteria, common in burns, ulcers and moist wounds. It needs medical review and often a swab to choose the right antibiotic.

Should I cover a wound that is draining?

Yes. Covering a draining wound with a clean, absorbent dressing protects it from germs, keeps the wound bed moist and protects clothing. Change the dressing when it becomes wet. Leaving a weeping wound open to the air can let it dry out and heal more slowly.