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

Antibiotics should only be prescribed to treat health problems:

• that are not serious but are unlikely to clear up without antibiotics – such as acne
• that are not 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

Learn about antibiotic resistance and why antibiotics are no longer routinely used to treat 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 who have a bacterial infection, or a higher than average risk of developing one
• people with heart failure
• people who have to take insulin for diabetes
• people with a weakened immune system – either because of an underlying health condition such as HIV or as a side effect of certain treatments, such as chemotherapy

Antibiotics are sometimes given as a precaution to prevent, rather than treat, an infection. This is called antibiotic prophylaxis. Situations where antibiotics are given as a preventive treatment include:

• if you're having an operation
• after a bite or wound that could get infected
• if you have a health problem that means you're at higher risk of infection, such as if you've had your spleen removed or you're having chemotherapy treatment

If you're having an operation

Antibiotics are normally recommended if you're having a type of surgery that carries a high risk of infection.

For example, you may be prescribed antibiotics if you're going to have:

• some types of eye surgery – such as cataract surgery or glaucoma surgery
• joint replacement surgery
• breast enlargement surgery
• pacemaker surgery
• surgery to remove the gallbladder
• surgery to remove the appendix

Your surgical team will be able to tell you if you need antibiotics.

Bites or wounds

Antibiotics 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

Some people are particularly vulnerable to infection, making antibiotics necessary. They include:

• people who have had their spleen removed
• people having chemotherapy for cancer
• people with sickle cell anaemia

In some cases, antibiotics are prescribed for people who have an infection that keeps coming back or that's causing distress or an increased risk of complications, such as: 

• cellulitis
• urinary tract infections
• genital herpes
• rheumatic fever