Antibiotics may be used to treat, or in some cases prevent, bacterial infections.

However, your GP will only prescribe antibiotics to treat:

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

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 risk than average of developing one
• people with heart failure
• people who have to take insulin to control their diabetes
• people with a weakened immune system – either due to an underlying health condition such as HIV or as a side effect of certain treatments such as chemotherapy

Intravenous antibiotics

Antibiotics are usually given as liquids, tablets or capsules. In more serious cases, injections or infusions of antibiotics can be given intravenously (directly into the blood or muscles).

Intravenous antibiotics are usually only required to treat more serious bacterial infections, such as:

• bacterial meningitis
• septicaemia (blood poisoning)
• infection of the outer layer of the heart (endocarditis)
• some cases of MRSA infection
• an infection that develops inside a bone (osteomyelitis)

Antibiotics to prevent infection

There are several circumstances in which you may be given antibiotics as a precaution to prevent, rather than treat, an infection. This is known as antibiotic prophylaxis.

For example, antibiotic prophylaxis is normally recommended if you are having surgery on a certain part of the body that is known to carry a high risk of infection or that could lead to devastating effects if it were to become accidentally infected.

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

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

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.

For example, an animal or human bite, 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, meaning antibiotic prophylaxis is necessary.

For example, people who have had their spleen removed or those with the blood disorder sickle cell anaemia, whose spleen does not work properly, should take antibiotics to prevent some infection. The spleen plays an important role in filtering out harmful bacteria from the blood.

In some cases, antibiotic prophylaxis is prescribed for people who experience a recurring infection that is causing distress or an increased risk of complications. For example: 

• cellulitis
• a urinary tract infection
• genital herpes
• rheumatic fever