penicillin v is the most common antibiotic used in the united states for strep throat. it is popular because it is safe, works well and does not cost much money. amoxicillin is usually used in europe. in india, it is more likely for people to get rheumatic fever. because of this, an injected medicine called benzathine penicillin g is the usual treatment. the antibiotics lower the average length of symptoms. the average length is three to five days. antibiotics lowers this by about one day. these medicines also reduce the spread of the illness. the medicines are used mostly to try to reduce rare complications. these include rheumatic fever, rashes, or infections. the good effects of antibiotics should be balanced by the possible side effects. antibiotic treatment may not need to be given to healthy adults who have bad reactions to medication. antibiotics are used for strep throat more often than would be expected from how serious it is and the speed at which it spreads. the medicine erythromycin (and other medicines, called macrolides) should be used for people who have bad allergies to penicillin. cephalosporins can be used in people with lesser allergies. streptococcal infections might also lead to swelling of the kidneys (acute glomerulonephritis). antibiotics do not reduce the chance of this condition.