How long after taking my last bactrim (sulfamethoxazole and trimethoprim) is it safe to drink alcohol? how long after last dose does it stay in your system?

50 hours: The half-life of Bactrim (sulfamethoxazole and trimethoprim) is about 10 hours. A drug should be completely out of your system after 5 half-lives; therefore, Bactrim (sulfamethoxazole and trimethoprim) should be out of your system within 50 hours or just over a day. Alcohol can interact with Bactrim (sulfamethoxazole and trimethoprim) and cause some unpleasant side effects such including: fast heartbeats, warmth or redness under your skin, tingly feeling, nausea, and vomiting.