Cloxacillin Capsules are used to treat a wide range of bacterial infections. These capsules are a type of penicillin antibiotic. The capsules work by stopping the growth of bacteria. These capsules are prescribed for the treatment of only bacterial infections. Cloxacillin Capsules are not used for the treatment of viral infections such as flu and the common cold. The capsules come in preventative packaging that keeps impurities and contaminants at bay.