Antibiotics (from 'anti' and 'life' in Ancient Greek) are powerful substances that prevent the growth of bacteria or destroy them completely. It is worth noting that their activity is aimed only at bacteria, while numerous diseases including common cold, sinusitis, and bronchitis are caused by viruses. Sometimes even a qualified physician cannot tell for sure what infection his patient has got - viral or bacterial. Common symptoms such as fever, nasal mucus as well as unhealthy condition during several days running do not always indicate suitability of antibiotics. For a right diagnosis, lab analysis may be required with testing and growing the culture from a sample taken.

Antibiotics do help to get rid of bacterial infections efficiently. Their effect becomes evident in 24 to 48 hours after starting a course of antibiotics. But even if a patient feels himself or herself perfectly well soon after taking a couple of dosages, it is highly recommended to go on with the prescribed medicine strictly keeping to the physician's recommendations. Only a complete course of antibiotics guarantees that the infection is really done. In other case, there remains a risk of infection recurrence.