At first, an infected wound may appear red and swollen. When touched, it will likely feel hot and tender. 

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You scraped your knee a few days ago. Now your cut is surrounded by angry, red skin that’s sore, warm to the touch, and emitting a gross amount of pus. You are suffering from an infected wound. Here’s how to recognize an infected would or cut and how to treat it before it gets worse.

Any damage to the skin that causes a break in the skin can lead to a wound infection. Generally, a wound will heal on its own. Things start to get complicated when germs enter the picture. That benign wound can turn into an infected cut once germs (i.e. bacteria) enter the sensitive tissue beneath the skin. Things can start to go south as quickly as two or three days after contact with the germ. The once uninfected wound will slowly become more painful, warm, swollen, red and pus-filled.

Signs of an Infected Wound

At first, an infected wound may appear red and swollen. When touched, it will likely feel hot and tender. As the infection worsens, the redness and swelling will spread and become more painful. Still not sure if you’re suffering from an infected cut? Here are 11 symptoms to look out for, says Dr. Meghan Feely, media expert for the American Academy of Dermatology and a board-certified dermatologist based in New York and New Jersey:

1. Reddened skin around the wound
2. Watery-looking fluid collecting in the wound
3. Warm skin around the wound
4. Tenderness on and around the wound
5. Honey-colored crusting
6. Blisters
7. Sores
8. Thick yellow, green or brown pus escaping from the wound that smells strong, pungent, foul or musty
9. Enlarged lymph nodes
10. Fever
11. Red steaks around the wound

How to Treat an Infected Wound

First, clean the wound (regular soap and water is fine or alcohol wipes if you’re away from a sink). Then remove any dirt, splinters or other debris from the cut. If the cut seems minor, and only shows a little red around its sides, add some antibiotic ointment (e.g. Neosporin), and cover with a bandage until it scabs over.

See your doctor if you notice the following:

• Signs of an infected wound (e.g. increased redness, pus, swelling, heat, and fever)
• A large, deep cut
• Debris inside the wound
• Unstoppable bleeding
• A cut resulting from an animal or human bite

Your doctor may take a culture to identify the organism to blame for your infection and will determine proper treatment for your infected wound. For instance, the “physician may prescribe a topical antibiotic as well as an oral antibiotic, based on your clinical presentation” Feely says.

If you are not up to date on your tetanus vaccination, your doctor may give you a tetanus shot to prevent the rare but serious complication of tetanus. If a wound infection spreads to your blood, you may develop a serious complication called sepsis. Sepsis requires intensive care treatment and possibly life support in a hospital.

Should You Cover an Infected Wound?

Yes. “In general, keep the site clean and covered,” Feely says. Not only will this help protect the wound from getting dirty (and therefore exposed to further bacteria), but it will also help to keep the medication on the infected cut. Make sure the dressing (i.e. a bandage or gauze) doesn’t stick to the cut. Depending on the location and severity of your infected cut, “your physician will discuss how frequently to change the dressing,” she explains.

Another risk of infection is picking scabs. Keeping your wound covered will help prevent you from picking at your cut or catching it on something that will pull off the scab.

Side Effects of an Infected Wound

Never ignore an infected cut, says Feely. In addition to more common unpleasant side-effects such as pain, redness, fever and swelling, an untreated infection could lead to cellulitis, a common bacterial infection of the skin that can spread to deeper tissues. “The infection, if left untreated, may spread from the skin to the lymphatics and bloodstream,” which could turn into a severe infection called sepsis and turn fatal, she warns.

In addition to these conditions, the following complications can also arise from an infected wound:

• Abscess (a painful, pus- and bacteria-filled mass)
• Death of tissue surrounding the infected cut (this could include muscle, connective tissue and bones)

When to See a Doctor for an Infected Cut

Once you’ve noted the tell-tale signs of an infected cut, see a doctor urgently, recommends Feely. You’ll likely need treatment with oral or topical antibiotics to prevent the spread of infection.

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This article was originally published in 2018. It is regularly updated.