Infection can develop in any type of wound. Wounds can be surgical (a cut made during an operation) or due to trauma. Traumatic wounds could be a result of falls, accidents, fights, bites or weapons. They may be cuts, lacerations or grazes. In certain types of wounds, developing an infection is more likely. Wound infections can be prevented.
How to tell if a wound is infected
The body is usually very good at healing wounds. Wound healing requires inflammation: the body activates the immune system to repair damage, and so inflammation is a good thing at the beginning of wound healing.
Sometimes wounds can become infected, which might make them slower to heal, or cause other problems, such as a serious infection that spreads.
The body reacts to infection by producing more inflammation. So, an infected wound might have signs of too much inflammation.
How to tell if a wound is healing or infected
Signs that a wound is healing normally include:
- The wound scabbing over.
- Mild redness or swelling around the wound (this is normal, and helpful, inflammation).
- Pink or red tissue at the bottom of the wound (called 'granulation tissue' - an important stage of healing).
- Mild warmth over the wound, which improves over time.
- Mild pain or discomfort which is improving over time.
- The wound gradually improving.
- Scar tissue developing (this is one of the last parts of wound healing).
Signs that a wound is infected include:
- Worsening pain at the site of the wound.
- Lots of swelling at the site of the wound.
- Discharge from the wound, particularly if pus is coming out of the wound (yellow-white liquid).
- The wound, or skin around it, feeling hot to touch.
- Redness that is spreading across the skin around the wound.
- Other signs of infection in the body, like having a fever, having general aches and pains, or feeling generally unwell.
- Having these symptoms may indicate a serious infection, such as sepsis.
It can sometimes be difficult to tell if a wound is infected. Speak to a healthcare professional if you're not sure.
What to do if a wound is infected
If you think a cut from an operation (a surgical wound) is infected, you should speak to a healthcare professional as soon as possible. If you can, it's best to contact the team who did the operation directly. If that's not possible, speak to your GP, or - in an emergency - attend the nearest Emergency Department.
A healthcare professional should ask you a few questions and then examine the wound to determine if it's infected or not.
If they think it's infected, they might take a swab (using a stick with a cotton bud on it) of the wound and any wound discharge.
This is sent to a laboratory to find out which bacteria are causing the infection, and which antibiotics work against them. It takes several days for the result to come back.
Sometimes, if a more serious infection is suspected, blood tests and scans might be needed. These are usually done in hospital.
If you have a laceration, cut or graze, watch it carefully. If a very small injury has become just a little bit red, you may be able to prevent further infection. You should:
- Keep it clean by bathing it with warm water and clean cotton wool.
- Try an antiseptic cream, such as Savlon®.
- If the redness is spreading or the wound starts to ooze pus, see your doctor or nurse.
- If it is a larger wound and seems to be developing infection, then see your doctor or nurse straight away.
How do you treat an infected wound?
Treatments for an infected wound include:
- No treatment: the body is usually good at fighting off minor infections, and very mild wound infections can sometimes be monitored to see if they get better on their own.
- Wound care: cleaning the wound every few days and applying sterile (clean) wound dressings. This is usually done by nurses. Some types of wound dressing are anti-bacterial.
- Antibiotic creams: creams such as fusidic acid can be used on minor wound infections.
- Antibiotic capsules and tablets: these are likely to be needed for large wounds, major infections, infections which are getting worse, and infections that are likely to get worse without treatment (such as surgical wound infections).
For severe wound infections, hospital treatment may be required:
- Antibiotics may need to be given intravenously (through a drip) for serious wound infections.
- Serious infections may require an operation ('debridement') to remove infected and dead tissue from the wound.
Do I need a tetanus injection?
Tetanus is a serious disease caused by germs which mostly live in soil or manure. Wounds which have been in contact with soil or manure, or which are particularly 'dirty', may put you at risk of developing tetanus. Tetanus is rare in the UK, because most people are protected from tetanus by vaccinations.
If you're fully up-to-date with your tetanus vaccines (you've had at least 3 vaccines, and the last vaccine was given less than 10 years ago), you don't need another vaccine after a wound.
If you've had at least 3 tetanus vaccines, but the last vaccine was given more than 10 years ago, you only need another tetanus vaccination if the wound is 'dirty' (eg, soil or dirt is in the wound). For a clean wound, you don't need another vaccination.
If you've never had the full initial course of tetanus vaccines (3 injections), or you're not sure, you should have a tetanus vaccine after any wound, even if it's a 'clean' one.
The rules are complicated, so ask a clinician if you are unsure.
Tetanus vaccines can be given by a nurse in a GP, or in the Emergency Department, if the wound requires treatment there.
Why do wounds get infected?
Wounds heal best when they are clean and free from germs. Normally, many germs live harmlessly on our skin and in the environment around us. Normally the germs live on our skin, or in areas such as our nose, without causing any problems.
Usually the skin acts as a barrier. If the skin is broken germs may spread into the more sensitive tissues underneath. This is how an infection can start. This makes the tissues sore and swollen, and less likely to heal. Open wounds are more likely than closed wounds to develop infections. This is because the break in the skin provides a route for the germs to travel from the outside to the inside.
Some circumstances make it more likely that wounds will become infected. These include:
- If you have diabetes (type 1 or type 2).
- If the object which caused the wound was dirty and contained germs.
- If the wound was caused by a human or animal bite. (Human and animal mouths contain lots of bacteria, and bites can make deep holes in the skin.)
- If the wound still contains a 'foreign body', ie bits of whatever caused the injury. For example, bits of glass, splinters of wood, thorns, etc.
- The size and depth of the wound. Larger or deeper wounds have a higher chance of becoming infected.
- Jagged edges to the wound.
- If proper precautions were not taken before an operation.
- If you are an older person. Your skin heals less well as you get older.
- If you are very overweight.
- If your immune system does not work as well as normal. For example, if you are on medication such as steroids or chemotherapy, or if you have HIV/AIDS.
Are wound infections dangerous?
Mild infections of small, shallow wounds can heal on their own, particularly in healthy people.
Sometimes, wound infections can spread and cause serious problems. This is more likely with large wounds, deep wounds, and surgical wounds, and in people who are more vulnerable to infection.
If a wound infection spreads, it can cause infection of the deep tissues under the skin (cellulitis). A severe wound infection may cause bacteria to enter the bloodstream, causing sepsis - which can be life-threatening.
Other possible complications include:
- The wound may not heal properly if it is infected.
- Other types of skin infection, such as impetigo.
- It can turn into a painful lump of pus called an abscess.
Very rare complications include:
- Developing a further infection with tetanus. This is very rare in the UK, because most people are vaccinated against it.
- Developing a further infection called necrotising fasciitis. Necrotising fasciitis is sometimes called 'flesh-eating disease'. In necrotising fasciitis, bacteria aggressively spread rapidly through the body, starting from the wound. It is very rare, but can be life-threatening.
How can I prevent wound infection?
Preventing infection in surgical wounds
When you have an operation the surgical team has strict procedures to try to help avoid infections. Surgical infections are monitored by Public Health England, so that policies can be changed and improved if needed.
There are a number of things you can do yourself to reduce your chances of infection. For example:
- Have a shower or bath before your operation and wash yourself with soap and water.
- Do not use a razor to shave the area to be operated on. This makes infection more likely. If the hair needs to be removed, your surgical team will do this with clippers.
- Remove all jewellery and nail polish before the operation.
- Keep the wound covered and the area around it clean. You can shower from two days after most operations.
- If you notice the skin around the wound becoming red or painful, see your doctor or nurse as soon as possible.
Preventing infection in wounds from injuries
Tips to avoid infection of traumatic wounds:
- Clean the wound and skin around it as soon as it happens. Use cool boiled water, or drinking-quality water.
- If you think there are still bits of foreign bodies in the wound, see your surgery nurse or go to your nearest Minor Injuries Unit or A&E to have it professionally cleaned out.
- If it is a very deep wound, or the edges are very far apart, or you cannot stop the bleeding, go to your nearest Minor Injuries Unit or A&E in case it needs stitches.
- Use an antiseptic around the wound area to help keep the germs away.
- Put a clean dressing over your wound to protect it from germs. Do not use gauze or a type of dressing which will stick to the wound. Your pharmacist should be able to advise you if the wound is too big for an ordinary plaster.
- Human or animal bites are very likely to become infected - seek medical advice at the earliest signs of this. If the injury is large, or there are multiple bite wounds, it may be worth taking antibiotics to prevent an infection. Seek advice straightaway in this case, rather than waiting for signs of infection to develop.
- Keep a close eye on the wound and seek medical advice if you think infection is developing.
- Arrange for a tetanus vaccination if needed.
Further reading and references
Surgical site infections: prevention and treatment; NICE guideline (April 2019 - last updated August 2020)
Bites - human and animal; NICE CKS, May 2023 (UK access only)
Lacerations; NICE CKS, December 2022 (UK access only)