evidence: Antibiotics treat infections caused by bacteria. But they don't treat infections caused by viruses (viral infections). For example, an antibiotic is the correct treatment for strep throat, which is caused by bacteria. But it's not the right treatment for most sore throats, which are caused by viruses. [...] Taking an antibiotic for a viral infection: [...] If you take an antibiotic when you have a viral infection, the antibiotic attacks bacteria in your body. These are bacteria that are helpful or are not causing disease. This incorrect treatment can then promote antibiotic-resistant properties in harmless bacteria that can be shared with other bacteria. Or it can create an opportunity for potentially harmful bacteria to replace the harmless ones.