Antibiotics are used to treat or prevent some types of bacterial infections. They aren't effective against viral infections, such as the common cold or flu.

Antibiotics should only be prescribed to treat conditions:

  • that aren't especially serious but are unlikely to clear up without the use of antibiotics – such as moderately severe acne
  • that aren't especially serious but could spread to other people if not promptly treated – such as the skin infection impetigo or the sexually transmitted infection chlamydia
  • where evidence suggests that antibiotics could significantly speed up recovery – such as a kidney infection
  • that carry a risk of more serious complications – such as cellulitis or pneumonia

Antibiotic resistance

Antibiotics are no longer routinely used to treat infections because:

  • many infections are caused by viruses, so antibiotics aren't effective
  • antibiotics are often unlikely to speed up the healing process and can cause side effects
  • the more antibiotics are used to treat trivial conditions, the more likely they are to become ineffective for treating more serious conditions

For example, antibiotics are no longer routinely used to treat chest infections, ear infections in children and sore throats.

Read more about antibiotic resistance.

People at risk of bacterial infections

Antibiotics may also be recommended for people who are more vulnerable to the harmful effects of infection. This may include:

  • people aged over 75 years
  • babies less than 72 hours old with a confirmed bacterial infection, or a higher than average risk of developing one
  • people with heart failure
  • people who have to take insulin to control their diabetes
  • people with a weakened immune system – either because of an underlying health condition such as HIV infection or as a side effect of certain treatments, such as chemotherapy

Antibiotics to prevent infection

Antibiotics are sometimes given as a precaution to prevent, rather than treat, an infection. This is known as antibiotic prophylaxis.

Antibiotic prophylaxis is normally recommended if you're having surgery on a certain part of the body which carries a high risk of infection or where infection could lead to devastating effects.

For example, it may be used if you're going to have:

Your surgical team will be able to tell you if you require antibiotic prophylaxis.

Bites or wounds

Antibiotic prophylaxis may be recommended for a wound that has a high chance of becoming infected – this could be an animal or human bite, for example, or a wound that has come into contact with soil or faeces.

Medical conditions

There are several medical conditions that make people particularly vulnerable to infection, making antibiotic prophylaxis necessary.

For example, the spleen plays an important role in filtering out harmful bacteria from the blood. People who have had their spleen removed, people having chemotherapy for cancer, or those with the blood disorder sickle cell anaemia, where their spleen doesn't work properly, should take antibiotics to prevent infection.

In some cases, antibiotic prophylaxis is prescribed for people who experience a recurring infection that's causing distress or an increased risk of complications, such as: 

Page last reviewed: 09/06/2016

Next review due: 01/12/2018