First-Generation Cephalosporins: What They Treat and How to Use Them
First-generation cephalosporins are antibiotics many doctors reach for when treating common bacterial infections. You’ve probably heard names like cephalexin, cefazolin, or cefadroxil. They work well against skin infections, simple wound infections, some throat infections, and certain urinary tract infections. These drugs are older, reliable, and often have fewer broad-spectrum effects than newer cephalosporins.
Why pick a first-generation cephalosporin? They target common gram-positive bacteria like Staphylococcus and Streptococcus. That makes them a good choice for cellulitis, uncomplicated skin abscesses after drainage, and some strep throat cases when penicillin isn’t an option. Cefazolin is also used before surgery to prevent wound infections because it’s effective and well-studied.
Common drugs and typical uses
Cephalexin (oral): Used for skin infections, uncomplicated UTIs, and throat infections. Dosing commonly ranges from 250 mg to 500 mg every 6–12 hours depending on the infection and patient factors.
Cefazolin (IV): Given in hospitals for surgical prophylaxis and moderate infections that need IV therapy. It’s often given as a single dose before an operation.
Cefadroxil (oral): Similar to cephalexin but has a longer half-life, so it can be dosed less often for the same types of infections.
What to watch for: side effects and allergies
Most people tolerate these antibiotics well. The most common side effects are stomach upset, diarrhea, and mild rash. If you get severe diarrhea, swelling, hives, or trouble breathing, stop the drug and get medical help right away.
Worried about penicillin allergy? Cross-reactivity between penicillins and first-generation cephalosporins is lower than once thought, but it’s not zero. If you had a severe penicillin allergy (anaphylaxis or severe rash), tell your prescriber— they may choose a different antibiotic or allergy testing.
Also mention other meds you take. Cephalosporins can interact with blood thinners like warfarin in some cases, altering how your blood clots. Your clinician will monitor or adjust doses if needed.
Resistance is a real concern. These drugs don’t work against all bacteria. If symptoms don’t improve within 48–72 hours of starting therapy, or if you get worse, contact your provider. They may need to culture the infection and change antibiotics based on results.
Pregnant or breastfeeding? Many cephalosporins are considered safe, but always check with your clinician. Dosage changes may be needed for kidney problems since these drugs are cleared by the kidneys.
Bottom line: first-generation cephalosporins are practical, focused antibiotics for common infections. Use them under medical guidance, report any serious side effects, and follow the full prescription to reduce resistance. If you’re unsure whether this class is right for your infection, your prescriber can explain the pros and cons for your situation.
, Apr, 27 2025
This article gets right into the details of first-gen and third-gen cephalosporin antibiotics, spotlighting their differences in bacterial coverage, common uses, and practical alternatives. Discover how their spectrums shape clinical decisions and why picking the right cephalosporin can make all the difference in treatment outcomes. Learn surprising facts about resistance trends and safety tips you’ll want to remember. If you’re considering options beyond Keflex, this guide gives you a direct link to an actionable resource. Perfect for anyone curious about smart antibiotic choices without wading through medical jargon.
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