If syphilis is not treated, complications of the disease can spread to other organs, resulting in neurological problems, like a stroke, paralysis, deafness, or dementia. Cardiovascular difficulties, like inflammation of the heart's major artery, the aorta, may also follow from untreated syphilis. Eventually these conditions can lead to death. The good news is that penicillin has been found to be a safe, effective treatment for this disease. A muscular injection of penicillin, sometimes with booster shots, is all that is needed to kill the bacterium that leads to syphilis. For people who are allergic to penicillin, a course of antibiotics may be taken to kill the bacteria, but damage already done by the disease cannot be reversed. Your doctor will follow up with blood tests to be sure that the medication is working. Pregnant women will be tested more frequently to ensure a return to health, as syphilis can cause death in newborns.