Antibiotics are a group of medicines designed to treat infections caused by bacteria. They don't work against infections caused by viruses.
The discovery of antibiotics has been one of the most important developments of modern medicine, but this powerful group of medicines needs to be used carefully.
What are antibiotics?
Antibiotics (or antibacterials) are a group of medicines that treat bacterial infections. In the past, other substances were found to kill bacteria, but many of these, such as mercury, were almost as dangerous to our own cells as the bacteria.
Antibiotics work because bacteria have certain differences from human cells, so they can kill the bacteria without hurting us.
In just a few short decades, the misuse and overuse of antibiotics have allowed some bacteria to genetically mutate to resist these medicines. This is called antibiotic resistance.
If bacteria become resistant to antibiotics, this means the antibiotics stop working and it is a serious threat to everyone’s health. Some bacteria, or 'super bugs', are now resistant to all known antibiotics and cannot be treated easily.
Read more about antibiotic resistance.
When should I take antibiotics?
In New Zealand, most antibiotics are available only with a prescription.
- They should be taken only as prescribed to treat bacterial infections that your natural immune system is having difficulty fighting off.
- Antibiotics are not usually recommended for infections like colds, coughs, flu and most ear, nose and throat infections, where they won’t make you get better any faster. If you have generally good health, your body’s immune system can easily fight these infections without antibiotics.
- Antibiotics are normally only prescribed for more serious infections caused by bacteria, like pneumonia, whooping cough and meningococcal disease. In these situations, antibiotics can be lifesaving.
- You should always take antibiotics according to the instructions, and complete the entire course even if you’re feeling better.
When not to take antibiotics
Unless you have been prescribed antibiotics as an early treatment for a chronic chest problem, you should not have antibiotics sitting around in your medicine cabinet. You should never take antibiotics that are left over from another illness or have been prescribed for another person.
- Antibiotics are no help against illnesses caused by a virus, such as the common cold and flu.
- Taking antibiotics unnecessarily for viral illnesses may increase the risk of bacteria developing resistance.
What are possible risks or side effects of antibiotics?
Different antibiotics affect people differently, but side effects include diarrhoea, nausea, vomiting and fungal infections. Many of these effects can be reduced by taking the medicine as directed, such as after a full meal or with a full glass of fluid.
- A small number of people might have a severe allergic reaction to some groups of antibiotics, such as penicillins.
- Always tell your doctor if you have had an allergic reaction to an antibiotic in the past. Describe the reaction and, if you can, tell them the name of that antibiotic.
- Care also needs to be taken if you have liver or kidney problems, you are taking other medicines or you are pregnant or breastfeeding.
- Some antibiotics need to be taken with food.
- Some don’t mix well with alcohol, while others affect certain other medicines, such as the anticoagulant warfarin.
That’s why it’s important to follow the instructions carefully.
Examples of antibiotics
|Examples of antibiotics used in New Zealand|
- Your family and antibiotics – what you need to know Pharmac, NZ
- Antibacterial drugs NZ Formulary