An infected leg typically shows five key signs: redness, swelling, warmth, pain, and tenderness. These can develop around a wound, surgical incision, bug bite, or even a small scratch you barely noticed. Knowing what to look for, and what separates a normal healing process from a worsening infection, can help you decide how quickly you need medical attention.
The Five Signs of Infection
Bacterial skin infections like cellulitis produce a consistent set of symptoms. The skin becomes red, swollen, warm to the touch, painful, and tender when pressed. These signs often overlap with normal inflammation from a healing wound, so the difference lies in degree and timing. A wound that’s slightly pink and tender for a day or two after an injury is healing. A wound that becomes increasingly red, hot, and painful three or more days later is likely infected.
The texture of your skin also matters. Infected skin sometimes develops a pitted, dimpled appearance similar to the surface of an orange peel. Blisters can form on or near the affected area. If the redness has a clear, spreading border rather than a faint pink halo, that’s a stronger indicator of infection.
What Wound Drainage Tells You
Not all fluid coming from a wound means infection. Clear or slightly tinted watery drainage (called serous drainage) is a normal part of healing. It contains proteins and white blood cells your body sends to repair the area.
Pus is the sign to watch for. It’s thick, milky fluid that can be white, yellow, green, pink, or brown. It typically smells bad. Pus is a mixture of dead cells, bacteria, and white blood cells, and it means your body is fighting an infection it can’t contain on its own. If the color or smell of the drainage changes over time, the infection is likely getting worse.
Signs the Infection Is Spreading
A localized infection on your leg can enter your bloodstream and become a systemic problem. The clearest warning sign is fever. A temperature of 100.4°F (38°C) or higher, measured orally, rectally, or by ear, is considered a fever and suggests your body is fighting something beyond a surface wound. Chills, fatigue, nausea, or a general feeling of being unwell alongside a red, swollen leg point toward a more serious infection.
On the skin itself, watch for redness that spreads rapidly beyond the original wound. A practical way to track this: use a pen or marker to draw a line around the border of the redness, then check again in a few hours. If the redness has moved past your line, the infection is actively spreading and you should seek care promptly.
When Pain Doesn’t Match the Wound
One of the most important warning signs is pain that seems far worse than the wound should cause. Severe pain that extends beyond the red, swollen area is an early indicator of necrotizing fasciitis, a rare but dangerous infection that destroys tissue beneath the skin. Early symptoms look similar to regular cellulitis (redness, warmth, swelling that spreads fast, fever), but the pain is disproportionate.
As necrotizing fasciitis progresses, the skin can change color, develop ulcers or black spots, and ooze pus. Dizziness, diarrhea, and extreme fatigue follow. This infection moves fast and requires emergency treatment. If you have a wound on your leg with escalating pain that doesn’t make sense for the size of the injury, don’t wait to see if it improves.
Infection vs. Blood Clot
A swollen, painful leg doesn’t always mean infection. Deep vein thrombosis (a blood clot in the leg) can produce similar symptoms: swelling, warmth, and pain. One useful distinction is the skin surface. Infected skin often has that dimpled, orange-peel texture, while a leg with a blood clot typically looks smooth and stretched. Infection also tends to produce obvious redness and often follows a visible wound, whereas a blood clot can develop without any break in the skin. Both conditions need medical evaluation, so if your leg is swollen and painful and you’re unsure of the cause, get it checked.
Who’s at Higher Risk
Some people are more likely to develop leg infections, even from minor injuries. Diabetes reduces blood flow and nerve sensation in the legs and feet, meaning wounds heal more slowly and you may not notice them early. Chronic swelling from lymphedema or venous insufficiency creates an environment where bacteria thrive. Obesity, a weakened immune system, and skin conditions like eczema or athlete’s foot (which create tiny breaks in the skin) all increase risk. If you fall into any of these categories, even a small cut or insect bite on your leg is worth monitoring closely.
What Treatment Looks Like
Most bacterial leg infections are treated with oral antibiotics. You can expect to start feeling better within 24 to 48 hours of starting treatment, but don’t be alarmed if the redness and swelling on your skin take 72 hours or longer to visibly improve. This lag is normal. If your symptoms are worsening rather than stabilizing after two to three days of treatment, contact your provider, as you may need a different antibiotic or further evaluation.
More severe infections, particularly those with high fever (103°F or above), rapid spreading, or signs of tissue damage, may require intravenous treatment in a hospital. The key factor in outcomes is how early you start treatment. Infections caught when the redness is small and the symptoms are local respond much more quickly than those that have been spreading for days.
How to Monitor at Home
If you have a wound or red area on your leg and you’re not sure whether it’s infected, track these things over 12 to 24 hours:
- Border of redness: Draw around it with a pen and check whether it expands.
- Temperature: Take your temperature twice a day. Anything at or above 100.4°F is a fever.
- Pain level: Note whether pain is staying the same, improving, or getting worse.
- Drainage: Watch for a shift from clear fluid to thick, discolored, or foul-smelling pus.
- Skin changes: Look for new blisters, dimpling, darkening skin, or streaks of redness extending away from the wound.
A wound that’s slowly improving with basic care (cleaning, keeping it covered, elevating the leg) is likely healing normally. A wound that’s getting redder, more swollen, more painful, or producing pus is infected and needs professional treatment. Trust the trajectory more than any single snapshot.