Amoxicillin vs. Cephalexin
See how Amoxicillin and Cephalexin compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Amoxicillin and cephalexin are both oral antibiotics used for many of the same respiratory, ear, and skin infections, but they come from different antibiotic classes with distinct allergy profiles.
Amoxicillin is a penicillin approved for a wider range of infections, including gonorrhea and H. pylori, while cephalexin is a cephalosporin often chosen for staph infections amoxicillin doesn't reliably cover.
Both are inexpensive generics, but cephalexin's price can climb higher at the top of its typical range than amoxicillin's.
Amoxicillin vs. Cephalexin Drug Summary
Amoxicillin
Amoxicillin is an aminopenicillin antibiotic used to treat ear, throat, respiratory, skin, and urinary infections, plus gonorrhea and H. pylori as part of combination therapy. It's taken orally as a capsule, tablet, chewable tablet, or liquid suspension, usually two to three times a day depending on the infection.
Cephalexin
Cephalexin is a first-generation cephalosporin antibiotic used to treat respiratory, ear, skin, bone, and urinary tract infections caused by susceptible bacteria. It's taken orally as a capsule, tablet, or liquid suspension, typically every 6 to 12 hours depending on the infection and dose.
Amoxicillin vs. Cephalexin Side Effects
Amoxicillin
Cephalexin
Amoxicillin vs. Cephalexin Dosage
Amoxicillin
Cephalexin
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg every 8 hours | At the start |
| Maximum dose | 1 g three times daily | If needed |
| Dose changes | 4 increases | As tolerated |
| 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 |
Amoxicillin
| STAGE | DOSE | WHEN |
| Starting dose | 250 mg every 8 hours | At the start |
| Maximum dose | 1 g three times daily | If needed |
| Dose changes | 4 increases | As tolerated |
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 |
Amoxicillin vs. Cephalexin Indications
Amoxicillin
Amoxicillin covers a broad range of common bacterial infections, from ear infections in children to urinary tract infections and uncomplicated gonorrhea in adults. It's also part of standard combination therapy for eradicating H. pylori, the bacteria linked to stomach ulcers.
Ear, nose, and throat infections
Lower respiratory tract infections
Skin and skin structure infections
Urinary tract infections
Gonorrhea and H. pylori (combination therapy)
Cephalexin
Cephalexin is FDA-approved for respiratory, ear, skin, bone, and genitourinary infections caused by susceptible strep and staph bacteria. It's often the choice when an infection specifically involves Staphylococcus aureus, since amoxicillin doesn't reliably cover it.
Respiratory infections (strep)
Otitis media (ear infections)
Skin and skin structure infections
Bone infections (staph, Proteus)
Genitourinary infections, including prostatitis
Amoxicillin vs. Cephalexin Pros and Cons
Amoxicillin
Amoxicillin has one of the longest safety track records of any antibiotic and is typically the first choice for common infections when no penicillin allergy exists. It's inexpensive and widely stocked, but it isn't effective against many staph infections and carries a well-known risk of rash in patients with mononucleosis.
Pros
Covers gonorrhea and H. pylori, unlike cephalexin
Decades of well-documented safety data since 1974
Available as a chewable tablet for easy pediatric dosing
Cons
Higher risk of rash in patients with mononucleosis
Doesn't reliably cover Staphylococcus aureus infections
Penicillin-class allergy risk, including rare anaphylaxis
Cephalexin
Cephalexin covers staphylococcal and some Proteus infections that amoxicillin can't reach, making it a go-to for certain skin, bone, and urinary infections. It requires dose adjustments in kidney impairment, and its FDA label doesn't specify exact side effect rates the way amoxicillin's does.
Pros
Covers Staphylococcus aureus and Proteus infections amoxicillin misses
FDA-approved for bone infections and acute prostatitis
Sometimes used off-label alongside acne treatment regimens
Cons
Requires dose adjustments for reduced kidney function
FDA label doesn't list specific side effect rates
Costs roughly $10 to $65 per 7-14 day course, which can run higher than amoxicillin's typical range
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