Bactrim vs. Macrobid

See how Bactrim and Macrobid compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Bactrim treats a broader range of infections, including UTIs, respiratory infections, and PCP, while Macrobid is approved only for uncomplicated urinary tract infections.

  • Bactrim carries a risk of serious skin reactions and is unsafe in infants or people with G6PD deficiency, while Macrobid carries risks of lung and liver toxicity with long-term use.

  • Bactrim is typically far less expensive than Macrobid, but the right choice depends on where the infection is and what's causing it.

Bactrim vs. Macrobid Drug Summary

Bactrim

Bactrim (sulfamethoxazole/trimethoprim) is a combination sulfonamide antibiotic that blocks two sequential steps in bacterial folate production. It's taken as an oral tablet, liquid, or IV infusion, usually every 12 hours, for infections like UTIs, bronchitis, and Pneumocystis pneumonia.

Macrobid

Macrobid (nitrofurantoin) is a urinary anti-infective that concentrates in urine rather than the bloodstream. It's taken as an oral capsule twice daily for 7 days, specifically for uncomplicated bladder infections.

Bactrim vs. Macrobid Side Effects

Bactrim

Most common
Nausea (rate not specified)
Vomiting (rate not specified)
Anorexia (rate not specified)
Rash (rate not specified)

Macrobid

Most common
Nausea (up to 8%)
Headache (up to 6%)
Flatulence (up to 1.5%)
Diarrhea (up to 1%)

Bactrim vs. Macrobid Dosage

Bactrim

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 800 mg/160 mg q12h At the start
Maximum dose 8-10 mg/kg/day If needed
Dose changes 3 increases As tolerated

Macrobid

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 100 mg every 12 hours Days 1-7
Maximum dose 100 mg every 12 hours Same as starting
Dose changes None Fixed dose

Bactrim vs. Macrobid Indications

Bactrim

Bactrim treats a broad range of bacterial infections, from urinary tract infections to Pneumocystis pneumonia. It combines two antibiotics that block sequential steps in bacterial folate production, which helps limit resistance.

  • Pneumocystis pneumonia (PCP) treatment and prevention

  • Shigellosis

  • Urinary tract infections

  • Acute otitis media in children

Macrobid

Macrobid is FDA-approved only for acute, uncomplicated urinary tract infections caused by E. coli or S. saprophyticus. It concentrates in urine rather than the bloodstream, so it isn't effective for infections outside the bladder.

  • Acute uncomplicated UTIs (cystitis)

  • Caused by E. coli or S. saprophyticus

  • Off-label: long-term prevention of recurrent UTIs

  • Not used for kidney infections (pyelonephritis)

Bactrim vs. Macrobid Pros and Cons

Bactrim

Bactrim is a low-cost combination antibiotic with FDA approval for several infection types, including UTIs, respiratory infections, and PCP prevention. It's widely stocked and generally covered by insurance without much hassle.

Pros

  • Covers a wide range of infections beyond the urinary tract

  • Used for both treatment and prevention of PCP in immunocompromised patients

  • Available as tablet, liquid, and IV formulations

Cons

  • Carries a risk of severe skin reactions (SJS/TEN)

  • Contraindicated in infants under 2 months old

  • Not safe in G6PD deficiency due to hemolytic anemia risk

  • Should be avoided during pregnancy and breastfeeding

Macrobid

Macrobid is a targeted urinary antibiotic that stays concentrated in the bladder, so it works well for uncomplicated UTIs but not for infections elsewhere in the body. It costs more than many older antibiotics and may need prior authorization from some insurers.

Pros

  • Remains reliably effective against E. coli despite decades of use

  • Stays concentrated in urine with minimal systemic absorption

  • Used off-label for long-term prevention of recurrent UTIs

Cons

  • Not approved for kidney infections or systemic infections

  • Contraindicated in significant kidney impairment

  • Long-term use linked to lung and liver toxicity

  • Costs more, roughly $80 to $200 per month without insurance

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