Clarithromycin is an antibiotic medicine which are derived from Saccharopolyspora erythraea. It helps to treat only bacterial infections and do not show any effect on viral infections like cold and flu. It is very effective for skin and respiratory problems. It is also known as a macrolide antibiotic and works by stopping the growth of the bacterias. Clarithromycin can also be used with other drugs to treat stomach ulcer, But is is advised to consult your doctor first if you are on other medications and have ever had liver or kidney problems in past. They are highly effective and can only be taken under the supervision of pharmacist.