Antibiotics kill bacteria. You usually take them as tablets. They can help men who have prostatitis because of a bacterial infection. But only about 1 in 10 men with prostatitis have a bacterial infection. 
In four studies, three-quarters of the men felt much better or completely better after taking antibiotics for four weeks.     The antibiotics used in these studies were ciprofloxacin (brand name Ciproxin), levofloxacin (Tavanic), azithromycin (Zithromax), doxycycline (Vibramycin), or lomefloxacin. Lomefloxacin isn't available in the UK.
In some studies, up to 9 in 10 men taking an antibiotic were cured.  But the men in these studies weren't compared with men taking a dummy treatment (a placebo). So we don't know how many men would have got better without the antibiotics.
One study found that taking antibiotics together with an alpha-blocker worked better than just taking an antibiotic.  Men who also took an alpha-blocker were less likely to have their prostatitis come back. The men in this study all had prostatitis caused by bacteria.
Two studies of men who didn't have a bacterial infection found that antibiotics didn't help.   But these men had severe symptoms for many years. So we can't say if antibiotics might help if you've only had symptoms for a short time, even if you don't have an infection.
All antibiotics have side effects. Ciprofloxacin, levofloxacin, and lomefloxacin may make you feel sick. They may also cause vomiting, heartburn, and diarrhoea. In studies, between about 5 in 100 and 20 in 100 men got stomach problems while they were taking antibiotics.  
Bacteria are tiny organisms. There are lots of different types. Some are harmful and can cause disease. But some bacteria live in your body without causing any harm.
A placebo is a 'pretend' or dummy treatment that contains no active substances. A placebo is often given to half the people taking part in medical research trials, for comparison with the 'real' treatment. It is made to look and taste identical to the drug treatment being tested, so that people in the studies do not know if they are getting the placebo or the 'real' treatment. Researchers often talk about the 'placebo effect'. This is where patients feel better after having a placebo treatment because they expect to feel better. Tests may indicate that they actually are better. In the same way, people can also get side effects after having a placebo treatment. Drug treatments can also have a 'placebo effect'. This is why, to get a true picture of how well a drug works, it is important to compare it against a placebo treatment.
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