Antibiotics are effective at treating

Antibiotics are used to fight bacteria. They are therefore not effective for treating colds, which are caused by viruses. In fact, overuse of antibiotics can lead to antibiotic resistance and reduced effectiveness when they are needed to fight a bacterial infection

It depends on the antibiotics. In theory, they can really only 'treat' bacterial infections or illnesses. The word antibiotic means 'anti-biologic' therefore it can mostly only treat bacterial illnesses, not virus illnesses or flesh wounds.