Macrobid vs. Cephalexin
See how Macrobid and Cephalexin compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Macrobid is a narrow-spectrum antibiotic reserved mainly for uncomplicated bladder infections, while cephalexin treats a much broader range of bacterial infections.
Both are short-course oral antibiotics, but Macrobid requires normal kidney function while cephalexin can be dose-adjusted for milder kidney impairment.
Macrobid's 7-day, twice-daily UTI regimen is more standardized than cephalexin's dosing, which varies widely depending on the infection being treated.
Macrobid vs. Cephalexin Drug Summary
Macrobid
Macrobid is a nitrofuran antibiotic used specifically to treat uncomplicated urinary tract infections caused by susceptible bacteria like E. coli. It's taken as an oral capsule, typically 100 mg every 12 hours for 7 days, and concentrates in urine rather than the bloodstream.
Cephalexin
Cephalexin is a first-generation cephalosporin antibiotic used for a wide range of bacterial infections, from skin and respiratory infections to bone and urinary tract infections. It's taken orally as a capsule, tablet, or liquid, usually several times a day depending on the infection being treated.
Macrobid vs. Cephalexin Side Effects
Macrobid
Cephalexin
Macrobid vs. Cephalexin Dosage
Macrobid
Cephalexin
| 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 |
| STAGE | DOSE | WHEN |
| Starting dose | 25-50 mg/kg/day divided | At the start |
| Maximum dose | 1 to 4 g/day divided | If needed |
| Dose changes | 4 increases | As tolerated |
Macrobid
| 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 |
Cephalexin
| STAGE | DOSE | WHEN |
| Starting dose | 25-50 mg/kg/day divided | At the start |
| Maximum dose | 1 to 4 g/day divided | If needed |
| Dose changes | 4 increases | As tolerated |
Macrobid vs. Cephalexin Indications
Macrobid
Macrobid treats acute, uncomplicated urinary tract infections caused by E. coli or S. saprophyticus. It's sometimes prescribed off-label at a lower dose to prevent recurrent UTIs, though that use isn't FDA-approved. It only reaches effective levels in urine, so it can't treat infections that have spread beyond the bladder.
Acute uncomplicated cystitis (FDA-approved)
Caused by susceptible E. coli or S. saprophyticus
Off-label: low-dose prophylaxis for recurrent UTIs
Not approved for kidney infections or abscess
Not approved for children under 12
Cephalexin
Cephalexin is a first-generation cephalosporin used for a wide range of bacterial infections, including strep throat, ear infections, skin infections, bone infections, and some urinary infections. It's also used off-label as an adjunct for acne and for surgical infection prevention. Its broad coverage makes it a common first choice for many outpatient infections.
Respiratory infections (strep throat, etc.)
Otitis media (ear infections)
Skin and soft tissue infections
Bone infections and some UTIs/prostatitis
Off-label: acne and surgical prophylaxis
Macrobid vs. Cephalexin Pros and Cons
Macrobid
Macrobid has stayed effective against E. coli for decades, largely because its narrow use has limited resistance. It only works in the urinary tract, so it can't be used for infections outside the bladder, and it carries specific warnings around long-term lung and nerve toxicity.
Pros
Still highly effective against E. coli after decades of use
Concentrates in urine, targeting bladder infections directly
Simple 7-day, twice-daily course for uncomplicated UTIs
Minimal systemic absorption limits some whole-body side effects
Cons
Contraindicated with reduced kidney function (CrCl under 60)
Risk of rare but serious lung, liver, and nerve toxicity
Not approved for kidney infections or children under 12
Roughly $80 to $200 per month without insurance, before savings programs
Cephalexin
Cephalexin's broad activity makes it a go-to choice for skin, respiratory, bone, and urinary infections alike. It's been used safely for decades and remains inexpensive as a generic, though its broader reach also means more chances for drug interactions or allergic cross-reactivity in penicillin-sensitive patients.
Pros
Covers a much broader range of infections than Macrobid
Available as capsule, tablet, or liquid for easier dosing
Long track record of safety since the early 1970s
Roughly $10 to $65 per course, often cheaper than Macrobid
Cons
Carries risk of C. difficile-associated diarrhea
Cross-reactivity risk in penicillin-allergic patients
Needs dose adjustment in significant kidney impairment
Dosing varies widely and often requires multiple daily doses
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