Can oseltamivir (Tamiflu) be given together with an antibiotic?

Yes, Tamiflu (Oseltamivir) Can Be Safely Given with Antibiotics

Oseltamivir can be safely co-administered with antibiotics because it has minimal drug interaction risk, is not metabolized by cytochrome P450 enzymes, and is primarily excreted unchanged through the kidneys. 1, 2

Pharmacokinetic Basis for Safety

• Oseltamivir undergoes minimal hepatic metabolism and does not interact with cytochrome P450 enzymes, eliminating the most common pathway for drug-drug interactions 1
• The drug is primarily excreted unchanged via the kidneys through glomerular filtration and tubular secretion via the anionic pathway 1, 3
• The FDA label explicitly states no dose adjustments are needed when coadministering oseltamivir with common medications including amoxicillin 2

Only Clinically Significant Interaction

• The only documented clinically significant interaction is with probenecid, which reduces oseltamivir carboxylate clearance by approximately 50% and doubles plasma levels through competition for renal tubular secretion 1, 4
• This interaction does not apply to antibiotics, which do not share probenecid's mechanism of competing for renal tubular secretion 4

Evidence Supporting Antibiotic Combinations

• Oseltamivir-azithromycin combination therapy demonstrated superior efficacy compared to oseltamivir alone in preventing Influenza-A (H1N1) complications, with significantly fewer secondary bacterial infections (10.4% vs 23.4%; P=0.019), shorter hospitalization (5.09 vs 6.58 days; P<0.0001), and less frequent need for respiratory support (17.6% vs 38.3%; P=0.016) 5
• Moxifloxacin can be safely combined with oseltamivir because these drugs use completely different metabolic pathways with no overlap 4

Administration Recommendations

• Administer oseltamivir 75 mg orally twice daily for 5 days, initiated within 48 hours of influenza symptom onset for maximum benefit 4, 6
• Give oseltamivir with food to minimize gastrointestinal side effects (nausea, vomiting) without affecting absorption 1, 4
• Continue the antibiotic at its standard dosing without adjustment 6

Dose Adjustment Caveat

• Reduce oseltamivir dose to 75 mg once daily if creatinine clearance is 10-30 mL/min 4, 6