I have been prescribed antibiotics – why?
If you have any questions or are unsure about how to take antibiotics, or if you have forgotten to take a dose of antibiotics, contact your doctor or pharmacist.
Any antibiotics left in the box at the end of your treatment should be returned to your pharmacist, who will dispose of them safely.
Antibiotics are pharmaceutical drugs (requiring a prescription) that kill bacteria or prevent them from reproducing. They are ineffective against infections caused by viruses, such as flu and COVID-19. In general, antibiotics are not needed for colds or gastrointestinal symptoms. Neither are antibiotics effective against fungal diseases or parasitic infections such as malaria. Antibiotics are given for bacterial infections that:
- are associated with a risk of complications
- are not likely to resolve without treatment (or not in a reasonable time-frame)
- might be transmitted to other people.
The decision on whether antibiotic treatment of an infection is necessary is often made either based on the patient's symptoms or following laboratory and diagnostic tests. Antibiotics are sometimes also prescribed preventively, for example just before an operation or when someone has been in close contact with a person with meningococcal meningitis (post-exposure prophylaxis).
Not all bacterial infections need antibiotic treatment. Some urinary tract or ear infections are readily cleared by the body's immune system, without the help of antibiotics. And antibiotics are not required for treating bronchitis, unless there is an underlying chronic pulmonary disease.
There are more than ten types of antibiotic – referred to as antibiotic “classes” – which allow the treatment of a range of diverse bacterial infections. All antibiotics work by preventing bacteria from producing substances that are vital to the bacteria (such as components needed for the construction of cell walls, proteins or DNA), but have only a minor effect on human cells, as they are structured differently.
It would be a mistake to think that all bacteria cause disease. In fact, all human bodies are covered in bacteria and constantly colonised by thousands of different strains. This complex mass of bacteria is called the microbiota, and includes the intestinal flora. It is essential for the microbiota to be in a steady state for the body to function correctly. A course of antibiotics can however disrupt this balance, by weakening or eliminating ‘useful’ bacteria such as those that help us digest our food, fight inflammation, or protect our skin and mucous membranes. The long-term effects of using antibiotics are still being investigated, but what is known is that the microflora of the skin or the gut may need up to 3-6 months to recover fully from a course of antibiotics.
Antibiotics can have side effects. The most common are digestive problems, diarrhoea, nausea, skin rash or kidney dysfunction. The presence and intensity of these effects varies considerably from one person to another. They also depend on the type of antibiotic used and on any other drugs or substances – including alcohol – that the person may be taking. A wide-ranging study in the USA found that 20% of all emergencies in paediatric wards were linked to the side effects of antibiotic drugs.