How do antibiotics work?
Antibiotics work by blocking vital processes in bacteria, killing the bacteria or stopping them from multiplying. This helps the body's natural immune system to fight the bacterial infection. Different antibiotics work against different types of bacteria.
- Antibiotics that affect a wide range of bacteria are called broad spectrum antibiotics (eg, amoxicillin and gentamicin).
- Antibiotics that affect only a few types of bacteria are called narrow spectrum antibiotics (eg, penicillin).
Different types of antibiotics work in different ways. For example, penicillin destroys bacterial cell walls, while other antibiotics can affect the way the bacterial cell works.
Doctors choose an antibiotic according to the bacteria that usually cause a particular infection. Sometimes your doctor will do a test to identify the exact type of bacteria causing your infection and its sensitivity to particular antibiotics.
Know the active ingredient
Antibiotic medicines may contain one or more active ingredients and be available under different brand names. The active ingredient is the chemical in a medicine that makes it work. The medicine label should tell you the active ingredient and the brand name.
To find out more about the active ingredient see the Consumer Medicine Information (CMI) for your brand of medicine, available on our Medicine Finder page or from your pharmacist or doctor.