Azithromycin vs. Bactrim
See how Azithromycin and Bactrim compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Azithromycin is a macrolide antibiotic usually given as a short 3-to-5-day course or a single dose, while Bactrim is a sulfonamide combination typically taken twice daily for 10 to 14 days.
Azithromycin treats respiratory infections, skin infections, and several sexually transmitted infections, while Bactrim is a go-to choice for urinary tract infections and pneumocystis pneumonia prevention.
Both can cause nausea and stomach upset, but azithromycin carries a heart-rhythm warning while Bactrim carries a higher risk of serious skin reactions and should be avoided in pregnancy.
Azithromycin vs. Bactrim Drug Summary
Azithromycin
Azithromycin is a macrolide (azalide) antibiotic used to treat respiratory infections, skin infections, and several sexually transmitted infections. It is typically taken as a short 3-to-5-day oral course or a single dose, and is also available as an intravenous infusion for more severe infections.
Bactrim
Bactrim is a combination sulfonamide antibiotic that blocks two steps in bacterial folate production, used for urinary tract infections, traveler's diarrhea, and pneumocystis pneumonia. It is usually taken as an oral tablet twice daily for 10 to 14 days, with an intravenous form available for hospitalized patients.
Azithromycin vs. Bactrim Side Effects
Azithromycin
Bactrim
Azithromycin vs. Bactrim Dosage
Azithromycin
Bactrim
| STAGE | DOSE | WHEN |
| Starting dose | 500 mg once | Day 1 |
| Maximum dose | 5 mg/kg once daily | Days 2-5 |
| Dose changes | 4 increases | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 800 mg/160 mg every 12h | At the start |
| Maximum dose | 8-10 mg/kg/day TMP q6-12h | If needed |
| Dose changes | 3 increases | As tolerated |
Azithromycin
| STAGE | DOSE | WHEN |
| Starting dose | 500 mg once | Day 1 |
| Maximum dose | 5 mg/kg once daily | Days 2-5 |
| Dose changes | 4 increases | As tolerated |
Bactrim
| STAGE | DOSE | WHEN |
| Starting dose | 800 mg/160 mg every 12h | At the start |
| Maximum dose | 8-10 mg/kg/day TMP q6-12h | If needed |
| Dose changes | 3 increases | As tolerated |
Azithromycin vs. Bactrim Indications
Azithromycin
Azithromycin is FDA-approved for a wide range of bacterial infections, including community-acquired pneumonia, sinusitis, and skin infections. It also treats certain sexually transmitted infections such as chlamydia-related urethritis and cervicitis. Its short dosing course makes it a common choice when adherence is a concern.
Community-acquired pneumonia
Acute bacterial sinusitis
Pharyngitis and tonsillitis
Skin and skin structure infections
Urethritis, cervicitis, and pelvic inflammatory disease
Bactrim
Bactrim is FDA-approved for urinary tract infections, traveler's diarrhea, and pneumocystis pneumonia, both to treat active infection and to prevent it in immunocompromised patients. It also treats shigellosis and certain ear infections in children. It is not approved for strep throat, unlike some other antibiotics.
Urinary tract infections
Pneumocystis jirovecii pneumonia (treatment and prevention)
Shigellosis
Acute otitis media in children
Traveler's diarrhea in adults
Azithromycin vs. Bactrim Pros and Cons
Azithromycin
Azithromycin's short 3-to-5-day or single-dose regimens make it easy to complete without missing doses. It covers a broader range of respiratory, skin, and sexually transmitted infections than Bactrim, but it carries a heart-rhythm warning that Bactrim does not share.
Pros
Short 3-to-5-day or single-dose regimens
Covers respiratory and skin infections plus several STIs
Long tissue half-life keeps drug levels up after the course ends
Not affected by G6PD deficiency
Cons
Carries an FDA warning for QT prolongation and abnormal heart rhythm
Can cause rare, serious liver injury
Not approved for urinary tract infections
Bacterial resistance to macrolides is increasingly common
Bactrim
Bactrim is inexpensive and effective against urinary tract infections and pneumocystis pneumonia, infections azithromycin is not approved to treat. It requires a longer 10-to-14-day course and carries added precautions around pregnancy and certain blood conditions.
Pros
Effective for urinary tract infections
Used to prevent and treat pneumocystis pneumonia
One of the least expensive commonly prescribed antibiotics
Long track record dating back to the 1970s
Cons
Requires a longer 10-to-14-day course in most cases
Higher risk of severe skin reactions like Stevens-Johnson syndrome
Contraindicated in pregnancy and in infants under 2 months
Can trigger hemolytic anemia in G6PD-deficient patients
Common Symptoms and Related Diseases You Can Explore
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