Cephalexin vs Amoxicillin

Cephalexin

Amoxicillin

Drug Class

Cephalosporin antibiotic

Penicillin-class antibiotic

Mechanism of Action

Inhibits bacterial cell wall synthesis by targeting penicillin-binding proteins, leading to bacterial death.

Indications

Skin infections - Respiratory tract infections - Bone infections - Otitis media (ear infections) - Urinary tract infections (UTIs)

Respiratory tract infections (e.g., pneumonia, bronchitis) - Ear infections (otitis media) - Sinusitis - Urinary tract infections (UTIs) - Skin infections - H. pylori infections (with other antibiotics)

Effective Against

Gram-positive bacteria (e.g., Staphylococcus and Streptococcus)

Gram-positive and some Gram-negative bacteria (e.g., E. coli, H. influenzae)

Dosage Forms

Capsules - Tablets - Suspension

Typical Dosage

Adults: 250–500 mg every 6–12 hours Children: 25–50 mg/kg/day divided into doses every 6–12 hours

Adults: 500–875 mg every 8–12 hours Children: 20–40 mg/kg/day divided into doses every 8–12 hours

Common Side Effects

- Diarrhea - Nausea - Vomiting - Abdominal pain - Allergic reactions (rash, itching)

Diarrhea - Nausea - Vomiting - Rash - Allergic reactions (anaphylaxis in rare cases)

Serious Side Effects

Clostridioides difficile infection - Severe allergic reactions - Stevens-Johnson syndrome (rare)

Clostridioides difficile infection - Severe allergic reactions (anaphylaxis) - Liver issues (elevated liver enzymes)

Contraindications

Allergy to cephalosporins or penicillins - History of severe hypersensitivity to beta-lactams

Allergy to penicillins or beta-lactams - Severe renal impairment (adjust dose)

Drug Interactions

Probenecid (increases cephalexin levels) - Anticoagulants (increased bleeding risk)

Allopurinol (increased rash risk) - Methotrexate (reduced clearance) - Oral contraceptives (reduced effectiveness)

Pregnancy Category

Category B: No evidence of harm in animal studies; considered safe during pregnancy.

Breastfeeding Safety

Safe: Small amounts pass into breast milk but generally safe.

Cost

Generally affordable; generic versions widely available.

Spectrum of Activity

Narrow spectrum; primarily effective against Gram-positive bacteria.

Broad spectrum; effective against Gram-positive and some Gram-negative bacteria.

Use in Special Populations

Adjust dose in renal impairment. Use cautiously in elderly patients.

Adjust dose in renal impairment. Generally safe for pediatric and elderly patients.

Brand Names

Keflex - Biocef - Keftab

Amoxil - Moxatag

Onset of Action

Typically within 1–2 hours after administration.

Half-Life

0.5–1.2 hours

1–1.5 hours

Coupon

Coupon Code

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Coupon Code

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Frequently Asked Questions

What is the difference between Cephalexin and Amoxicillin?

Cephalexin is a cephalosporin antibiotic, while amoxicillin is a penicillin-type antibiotic. Both fight bacterial infections but belong to different drug families and may work better for different types of infections.

Which is stronger: Cephalexin or Amoxicillin?

Neither is universally stronger. Cephalexin may work better for skin infections, while amoxicillin is often preferred for ear, throat, or respiratory infections. The choice depends on the type of bacteria causing the infection.

Can I switch from Amoxicillin to Cephalexin?

Switching between antibiotics should only be done with a doctor\'s advice. Different bacteria respond to different antibiotics, and using the wrong one may not treat the infection properly.

Which has fewer side effects: Cephalexin or Amoxicillin?

Both antibiotics can cause side effects like diarrhea, nausea, and rash. Overall, they are usually well-tolerated, but the risk of side effects can vary depending on individual allergies or sensitivities.

Are Cephalexin and Amoxicillin safe for people allergic to penicillin?

If you\'re allergic to penicillin, you may also react to cephalexin, although the risk is lower. Always tell your doctor about any allergies before starting either medication.

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