Antibiotics help fight infections caused by bacteria, like strep throat. They also can be used to prevent infection before surgery — a practice called prophylaxis. Antibiotics kill or slow the growth of bacteria by targeting their DNA, cell walls, or other proteins. Different antibiotics target different types of bacteria. For example, some work against aerobic (living) bacteria while others attack anaerobic (nonliving) ones.
In general, antibiotics are safe for most people. However, some antibiotics can cause side effects, such as nausea, vomiting, or diarrhea. These side effects are usually mild and go away as the antibiotics clear your body of bacteria.
The antibiotics most likely to have serious side effects are those that target the nervous system, blood, kidneys, or intestines. Some examples are penicillins (which can cause haemolytic anaemia, thrombocytopenia), rifamycins (which can induce neurological damage), and aminoglycosides (which can induce renal toxicities).
It’s important to take the full course of antibiotics as prescribed by your doctor. The exact length of time will vary, depending on the type and severity of your infection. You may start to feel better before the antibiotics finish working in your body. In some cases, antibiotics must be taken with food to avoid stomach upset.
Overusing and misusing antibiotics can make bacteria resistant to them, which makes it harder for doctors to treat infections. If you think you need to use antibiotics, talk to your doctor about how to use them safely. Follow the instructions in your medication packet and check the patient information leaflet for more advice.