How to use Bactrim DS. Take this medication by mouth, as directed by your doctor, with a full glass of water (8 ounces / 240 milliliters). If stomach upset occurs, take with food or milk. It can be the side effect, though it's rarely happen. Get medical help right away if any of these rare but serious side effects occur: persistent Note: This document contains side effect information about sulfamethoxazole / trimethoprim. Some of the dosage forms listed on this page may not apply to the brand name Bactrim. Bactrim (sulfamethoxazole and trimethoprim) DS is a combination of two antibiotics used to treat urinary tract infections, acute otitis media, bronchitis, Shigellosis, Pneumocystis pneumonia, traveler's diarrhea, methicillin-resistant Staphylococcus aureus , and other bacterial infections susceptible to this antibiotic. Bactrim (sulfamethoxazole and trimethoprim) is an antibiotic used to treat ear infections, urinary tract and other infections. Includes Bactrim side effects, interactions and indications. Can Bactrim cause Headaches? Headaches is a known side effect of Bactrim. Complete analysis from patient reviews and trusted online health resources, including first-hand experiences. Summary. Common Bactrim side effects may include nausea, diarrhea, vomiting, headaches, and sensitivity to light. More serious side effects can occur occasionally, such as muscle weakness and pain, goiter, and dizziness. Summary. Headache is found among people who take Bactrim, especially for people who are female, 60+ old , have been taking the drug for 1 month, also take medication Prednisone, and have High blood pressure. Bactrim is the brand name of the generic antibiotic sulfamethoxazole trimethoprim (sometimes called co-trimoxazole). The drug is a combination of two antibiotics: It's one part trimethoprim (a. Unnecessary use or misuse of any antibiotic can lead to its decreased effectiveness. HOW TO USE: Take this medication by mouth, as directed by your doctor, with a full glass of water (8 ounces / 240 milliliters).