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 can I tell if a wound is infected?
A wound which has become, or is becoming, infected may:
- Become more painful, instead of gradually improving.
- Look red around the skin edges. This red area may feel warm or hot.
- Look swollen.
- Ooze a yellow material (pus) which may be smelly.
If the infection spreads further, the redness will keep spreading to more areas of skin. You may feel unwell in yourself, with a temperature and aches and pains.
What should I do if my wound is infected?
If you think a cut from an operation (a surgical wound) is infected, you should speak to the nurse or doctor at your surgery as soon as possible. They may want to see you in the surgery to take a sample of any discharge from an infected cut with a stick which looks like a large cotton bud. This is called a swab. The swab is sent to the laboratory to find out which germs are causing the infection. Your nurse or doctor will help keep your wound clean, and prescribe treatment if needed (see below.)
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. 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 then see your doctor or nurse. If it is a larger wound and seems to be developing infection then see your doctor or nurse straightaway.
How do you treat an infected wound?
Unless the infection is very minor, antibiotics are usually needed to treat the infection and stop it spreading. If the wound and/or area of infection are small then an antibiotic cream such as fusidic acid may be prescribed. If the wound is larger, or the infection seems to be getting worse, then an antibiotic to be taken by mouth (oral antibiotic) is needed.
The nurse will also cleanse your wound and provide suitable dressings to cover and protect it.
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. Most people are protected from tetanus by the routine vaccination programme.
If you have a 'dirty' wound and have not had the full tetanus vaccination course, or if you are not sure, contact a nurse (at your general practice or at A&E) as soon as possible as you may need a 'booster'.
Why do wounds become 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.
- 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.
What are the complications of an infected wound?
If a wound infection is not quickly and successfully treated, it may spread. The surrounding skin may become red and swollen and sore. The infection may spread to the deeper tissues beneath the skin. This spreading infection is called cellulitis. As the infection spreads, it may spread through the blood right through your system, making you feel unwell in yourself. This can give you a temperature and may develop into severe infection called sepsis.
If you have a wound and start to feel unwell in yourself, it is very important to know the signs of possible sepsis. Sepsis is always a medical emergency - if you have any concern that you might be developing sepsis, seek immediate medical help.
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.
- Developing a further infection called necrotising fasciitis, known as the 'flesh-eating bug'. This is a very rare severe condition where large areas of the skin become very damaged and painful.
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.
- 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 having antibiotics 'in case'. 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, October 2018 (UK access only)
Lacerations; NICE CKS, October 2018 (UK access only)