Antibiotics are the standard treatment for kidney infections. If you have an uncomplicated kidney infection and you're well enough not to need treatment in hospital, you'll be given antibiotic tablets to take at home. You'll probably be given tablets for one or two weeks, depending on how severe your infection is.  Some doctors recommend that you take antibiotics for at least 10 days.  (An uncomplicated infection occurs when a person with a normal urinary tract and a healthy immune system gets infected with a common type of bacteria. To read more, see Types of kidney infection.)
Medical studies often compare a treatment with a dummy treatment (a placebo). However, these types of study can't be done for people with kidney infections. Antibiotics have been used for a long time and doctors know they work. So it would be unfair not to give some people antibiotics, just to do a study.
However, researchers have looked at how well the different antibiotics work compared with each other. Two reviews of the research compared several antibiotics and found they all worked about as well as each other.  
Some of the antibiotic tablets that have been studied for people with kidney infections are:
Some doctors prefer not to use ampicillin or amoxicillin because the bacteria that cause kidney infections are becoming increasingly resistant to them. This means that these drugs no longer kill some kinds of bacteria. Some guidelines do not recommend use of the antibiotic trimethoprim for a similar reason: that resistance is too common for use in a serious condition such as kidney infection. 
How resistant bacteria are to particular antibiotics varies from place to place. In some areas, doctors are also advised not to prescribe co-trimoxazole unless they've done tests to make sure the bacteria causing the infection aren't resistant to it.  
There hasn't been any research to say whether antibiotic drips work better than tablets, or how long you need to take antibiotics.
You should always finish your course of treatment, even if you're feeling better. This is to ensure you don't have low levels of bacteria, which may not cause symptoms but could infect someone else.
Antibiotics can cause side effects. Some people get diarrhoea, but antibiotics can also cause more serious problems. For example, it's possible to get inflammation of the bowel.  Older people are especially at risk.