Bactrim (co-trimoxazole) is often recommended for the treatment of infections caused by the presence and multiplication of bacteria in your body. This drug is efficient if taken exactly as prescribed with a glass of water. As most antibiotics Bactrim is supposed to be taken regularly for you to benefit, and it's very important to use the entire amount of this drug. If you stop the treatment before it's time - there is a chance your infection may return, but this time taking Bactrim will not be enough as it will have developed resistance to this drug. Therefore, you will need to make sure your treatment goes according to plan. There are different factors that may affect the treatment - such as medical conditions you have or other drugs you are using. Please tell your doctor if you have glucose-6-phosphate dehydrogenase deficiency, severe allergies, liver disease, folic acid deficiency, AIDS, malnourishment, asthma, or kidney disease, as those factors may affect the dose of Bactrim you are prescribed. The following side effects are sometimes possible: loss of appetite, sleep problems, spinning sensation, upset stomach, joint pain, swollen tongue, vomiting, and dizziness.