Key takeaways
Azithromycin (Zithromax) and sulfamethoxazole/trimethoprim (Bactrim, Septra) are both antibiotics, but they belong to different classes and treat different types of infections. Azithromycin is a macrolide antibiotic taken once daily, typically for 3 to 5 days, and is used for infections like strep throat, sinus infections, and pneumonia. It works by stopping bacteria from making certain proteins. On the other hand, sulfamethoxazole/trimethoprim is a combination of a sulfonamide and an antifolate, taken twice daily, and is used for urinary tract infections, ear infections, and certain types of pneumonia. It works by stopping bacteria from making folic acid. Both are available as generic and come in tablet, liquid, and injectable forms. Azithromycin can cause side effects like diarrhea and stomach pain, whereas sulfamethoxazole/trimethoprim can cause nausea, rash, and increased sensitivity to sunlight. Both medications have serious side effects, but sulfamethoxazole/trimethoprim is not recommended during pregnancy and can cause low sodium and high potassium levels.
