If you are given an antibiotic to treat an STD, it's important that you take all of the drug, even if the symptoms go away. Also, never take someone else's medicine to treat your illness. By doing so, you may make it more difficult to diagnose and treat the infection. Likewise, you should not share your medicine with others. Some doctors, however, may provide additional antibiotics to be given to your partner so that you can be treated at the same time. Consider that not having sex or sexual relations (abstinence) is the only sure way to prevent STDs.Use a latex condom every time you have sex. (If you use a lubricant, make sure it is water-based.) Limit your number of sexual partners. The more partners you have, the more likely you are to catch an STD. Don't use alcohol or drugs before you have sex. You may be less likely to use a condom if you are drunk or high. Learn about STDs. The more you know, the better you can protect yourself. Know the signs and symptoms of STDs. Look for them in yourself and your sex partners.