Taking Oral Bactrim and Clindamycin Together
Yes, oral Bactrim (trimethoprim/sulfamethoxazole) and clindamycin can be taken together when clinically indicated, as there are no significant drug interactions between these two antibiotics that would contraindicate their concurrent use.
Rationale for Combination Use
The combination of these antibiotics may be appropriate in certain clinical scenarios:
Expanded Coverage:
- Bactrim provides good coverage against many gram-negative organisms and some gram-positive bacteria
- Clindamycin offers excellent coverage against gram-positive organisms (including some MRSA) and anaerobes
Specific Clinical Indications:
- Animal bites: For patients with severe penicillin allergies, the combination of trimethoprim-sulfamethoxazole plus clindamycin is recommended 1
- Polymicrobial infections: When both gram-positive and gram-negative coverage is needed
- Certain skin and soft tissue infections: Particularly those involving suspected MRSA 2
Evidence Supporting Combination Use
In vitro studies have shown that clindamycin in combination with other antibiotics typically shows no antagonistic effects against common infectious microorganisms and may even demonstrate synergistic effects 3
Clinical studies comparing Bactrim and clindamycin individually for MRSA skin infections have shown similar efficacy rates, suggesting they can be effective when used appropriately 4, 2
Considerations When Using This Combination
Potential Side Effects to Monitor
Gastrointestinal effects:
- Both medications can cause diarrhea
- Increased risk of Clostridioides difficile infection
- Monitor for severe diarrhea or abdominal pain
Skin reactions:
- Both medications can cause rash
- Bactrim has higher risk of severe skin reactions (Stevens-Johnson syndrome)
Hematologic effects:
- Bactrim can cause bone marrow suppression
- Monitor for unusual bleeding or bruising
Electrolyte abnormalities:
- Bactrim can cause hyperkalemia and hyponatremia, especially at high doses 5
Dosing Considerations
Standard adult dosing:
- Bactrim DS: 1-2 tablets (160mg TMP/800mg SMX per tablet) every 12 hours
- Clindamycin: 300-450mg every 6-8 hours
Renal adjustment:
- Bactrim requires dose adjustment when creatinine clearance is <30 mL/min 6
- Clindamycin does not typically require renal adjustment
Special Populations
Pediatric Patients
- For children with MRSA infections, if using clindamycin: 10-13 mg/kg/dose IV every 6-8 hours (to administer 40 mg/kg/day) 1
- Pediatric Bactrim dosing is weight-based
Pregnancy
- Both medications are generally avoided in pregnancy when possible, but the benefits may outweigh risks in serious infections
Clinical Pearls
Always consider source control: For abscesses, incision and drainage remains critical regardless of antibiotic choice 2
Duration of therapy should be determined by the specific infection being treated:
- Uncomplicated skin infections: 5-10 days
- Complicated skin/soft tissue infections: 7-14 days
- Osteomyelitis: 4-6 weeks 7
Monitor for adverse effects more closely when using combination therapy, as the risk of side effects may be additive
Ensure adequate hydration to prevent crystalluria with Bactrim 5
By following these guidelines and monitoring appropriately, the combination of oral Bactrim and clindamycin can be used effectively and safely when clinically indicated.