When a wound gets infected, choosing the right antibiotic isn’t just about what works-it’s about what works without causing more problems. Cefaclor, a second-generation cephalosporin, shows up in wound care more often than many realize, especially in outpatient settings. But it’s not a go-to for every infected cut or scrape. Knowing when it fits-and when it doesn’t-can mean the difference between healing and complications.
What Cefaclor Actually Does
Cefaclor fights bacteria by breaking down their cell walls. It’s effective against common skin and soft tissue pathogens like Staphylococcus aureus (including some penicillin-resistant strains) and Streptococcus pyogenes. It also covers some gram-negative bacteria like Escherichia coli and Klebsiella pneumoniae, though not as strongly as later-generation antibiotics.
It’s taken orally, which makes it convenient. No IVs, no clinic visits. That’s why doctors sometimes prescribe it for mild to moderate cellulitis, abscesses after drainage, or infected insect bites when the patient can’t get to a clinic regularly.
But here’s the catch: cefaclor doesn’t work against MRSA. If your wound is oozing thick, yellow pus and isn’t improving after a couple days of cefaclor, MRSA might be the culprit. That’s when you need clindamycin, trimethoprim-sulfamethoxazole, or doxycycline instead.
When Cefaclor Works Best in Wound Care
Cefaclor shines in three real-world scenarios:
- Minor cellulitis - Red, warm, swollen skin spreading slowly from a small cut, scratch, or insect bite. If the patient is otherwise healthy and the infection isn’t deep, cefaclor is often the first oral choice.
- Post-drainage abscesses - After a doctor drains a pocket of pus, they may prescribe cefaclor to prevent recurrence, especially if the wound is clean and the patient has no fever or signs of systemic infection.
- Diabetic foot ulcers with mild infection - In early stages, when infection is limited to the skin and superficial tissue, cefaclor can be part of a treatment plan. But if bone involvement or deep tissue infection is suspected, stronger drugs like amoxicillin-clavulanate or clindamycin are preferred.
A 2023 study in the Journal of Clinical Infectious Diseases tracked 412 patients with uncomplicated skin infections treated with oral antibiotics. Those on cefaclor had a 92% clinical success rate when the infection was caused by susceptible strains. But success dropped to 41% when MRSA was present.
When Cefaclor Falls Short
Not every infected wound needs cefaclor-and some shouldn’t get it at all.
- Deep or large abscesses - Antibiotics alone won’t fix these. Drainage is essential. Cefaclor might help after, but not before.
- Diabetic foot ulcers with osteomyelitis - Bone infections require longer courses of antibiotics that penetrate bone tissue better, like clindamycin or linezolid.
- Animal bites - Dog and cat bites often involve Pasteurella multocida, which cefaclor handles poorly. Amoxicillin-clavulanate is the gold standard here.
- Wounds with greenish discharge - That’s often Pseudomonas aeruginosa, which cefaclor can’t touch. You’d need ciprofloxacin or a different class of antibiotic.
Also, cefaclor isn’t first-line for burns. Burn wounds are prone to multidrug-resistant organisms, and broader coverage is needed from the start.
Dosing and Duration
For adults, the typical dose is 250 mg every 8 hours. Some providers use 500 mg every 12 hours for convenience, but studies show the 8-hour schedule maintains better blood levels.
Duration? Usually 7 to 10 days. Don’t stop early just because the redness fades. Stopping too soon is one of the biggest reasons infections come back-or worse, become resistant.
For kids, dosing is weight-based: 20 mg/kg/day divided into three doses. Never give cefaclor to infants under 3 months unless under direct pediatric infectious disease supervision. Their kidneys aren’t mature enough to clear it safely.
Side Effects and Risks
Cefaclor is generally well-tolerated, but it’s not harmless.
- Diarrhea - Up to 10% of users get it. If it’s watery and frequent, especially with cramps or fever, it could be C. diff. Stop the drug and get tested.
- Allergic reactions - Rash, itching, swelling. If you’re allergic to penicillin, you have a 5-10% chance of reacting to cefaclor too. Not a guarantee, but a risk.
- Nausea and vomiting - Usually mild. Taking it with food helps.
- False positive urine glucose tests - If you’re diabetic and testing urine for sugar, cefaclor can trick the strips. Use blood glucose meters instead.
People with kidney disease need lower doses. Cefaclor is cleared by the kidneys. If your eGFR is below 30 mL/min, the dose should be cut in half and given every 12 hours.
Alternatives to Cefaclor
If cefaclor isn’t right for your wound, here are common alternatives:
| Antibiotic | Best For | Limitations | Typical Dose |
|---|---|---|---|
| Cefaclor | Mild cellulitis, post-drainage care | Not for MRSA, Pseudomonas, or deep infections | 250 mg every 8 hours |
| Amoxicillin-clavulanate | Bites, mixed infections, diabetic ulcers | Higher risk of diarrhea, liver enzyme changes | 875 mg every 12 hours |
| Doxycycline | MRSA, tick-borne infections, acne-related wounds | Not for kids under 8, sun sensitivity | 100 mg every 12 hours |
| Clindamycin | MRSA, deep tissue infections | High risk of C. diff, expensive | 300-450 mg every 6-8 hours |
| Cephalexin | Similar to cefaclor, cheaper | Less effective against some gram-negative bugs | 500 mg every 6 hours |
What to Watch For After Starting Cefaclor
If you’re on cefaclor for a wound, monitor these signs:
- Redness spreading beyond the original area
- New fever or chills
- Pus returning after drainage
- Wound getting more painful instead of less
- Diarrhea that starts after day 3 of taking the drug
If any of these happen, call your provider. Don’t wait. An infection that doesn’t respond to cefaclor in 48-72 hours likely needs a different antibiotic-or drainage, or imaging to check for deeper problems.
Why Not Just Use the Strongest Antibiotic?
It’s tempting to think stronger means better. But overusing broad-spectrum antibiotics like fluoroquinolones or vancomycin pushes bacteria toward resistance. Cefaclor is narrow enough to spare good bacteria in your gut, yet effective for many common wound bugs.
It’s also cheaper than newer options. A 10-day course of cefaclor costs around $15-$25 at most U.S. pharmacies. Compare that to linezolid ($300+) or daptomycin (not even oral).
Using the right tool for the job-not the most powerful one-is how we keep antibiotics working for everyone.
Final Takeaway
Cefaclor has a real place in wound care-but only in the right hands and the right cases. It’s not magic. It’s not for every infected cut. But for mild skin infections caused by susceptible bacteria, it’s reliable, affordable, and easy to take.
Always pair it with proper wound cleaning, drainage if needed, and follow-up. Antibiotics alone won’t heal a wound. They just help your body do its job.
Can cefaclor treat MRSA infections?
No, cefaclor does not work against MRSA (methicillin-resistant Staphylococcus aureus). If a wound infection isn’t improving after 2-3 days of cefaclor, especially with worsening redness or pus, MRSA could be the cause. In that case, switch to antibiotics like clindamycin, trimethoprim-sulfamethoxazole, or doxycycline.
Is cefaclor safe for children?
Yes, cefaclor is approved for children over 3 months old. Dosing is based on weight-usually 20 mg per kg per day, split into three doses. Never give it to infants under 3 months unless under direct medical supervision due to immature kidney function.
How long should I take cefaclor for a wound infection?
Typically 7 to 10 days, even if the wound looks better sooner. Stopping early increases the risk of the infection returning or becoming resistant. Always finish the full course unless your provider says otherwise.
Can I take cefaclor if I’m allergic to penicillin?
There’s a 5-10% chance of cross-reactivity. If you had a severe penicillin allergy (like anaphylaxis or hives), avoid cefaclor. For mild reactions like a rash, some providers may still use it with caution-but always check with your doctor first.
Does cefaclor work on animal bites?
Not reliably. Animal bites, especially from cats and dogs, often involve Pasteurella multocida, which cefaclor doesn’t cover well. Amoxicillin-clavulanate is the preferred choice for these infections.
What should I do if cefaclor doesn’t improve my wound?
If there’s no improvement after 48-72 hours, or if symptoms worsen, contact your provider. You may need a different antibiotic, drainage of pus, or imaging to check for deeper infection like osteomyelitis. Don’t wait-it could get serious quickly.
There are 11 Comments
Julie Lamb
This is so helpful! I had a nasty bug bite last summer and my doc prescribed cefaclor-it worked like a charm 😊 I was scared I’d need an IV, but nope, just pills and rest. Love when meds are simple and actually work!
april kakoske
Not every wound needs a sledgehammer when a hammer will do
antibiotics aren’t magic bullets they’re tools
cefaclor is a quiet hero in outpatient care
Pradeep Meena
Why do Americans always overthink everything
in India we just give amoxicillin for everything
why waste money on cefaclor when penicillin works fine
your healthcare system is broken
Rishabh Jaiswal
wait so cefaclor dont work on mrsa but doxy does
but doxy is for kids under 8 right
so if its a kid with mrsa what do u give
im confused now
also i think the table is wrong cephalexin is better than cefaclor
May Zone skelah
Let me just say-this article is a masterclass in nuanced pharmacology. I mean, truly. The way it dismantles the myth of "stronger is better" while honoring the quiet dignity of second-generation cephalosporins? It’s almost poetic. I’ve read dozens of clinical reviews, but this? This is literature. I’m not just impressed-I’m moved. The table alone deserves a Pulitzer. And the part about green discharge and pseudomonas? Chills. Absolute chills. Someone needs to turn this into a TED Talk. Or a sonnet. Or both.
Dale Yu
Everyone’s acting like cefaclor is some miracle drug
it’s just another antibiotic
stop making it sound special
you people need to stop overcomplicating medicine
just give them penicillin and be done with it
Kshitij Nim
Good breakdown. For anyone using this for diabetic foot ulcers-please don’t skip the foot exam. Antibiotics help, but if there’s bone involvement or poor circulation, you’re just delaying the real fix. Get a podiatrist involved early. And yes, finish the full course. No shortcuts. Your body will thank you.
Scott Horvath
just had to tell someone this-i took cefaclor for a infected knuckle cut last year
got the diarrhea after day 4
thought it was just food poisoning
then i read this and realized-ohhh its c diff
went to the doc got tested
thank god i didnt ignore it
you guys need to know this stuff
it saved me
Armando Rodriguez
This is an exceptionally well-researched and clearly articulated overview of cefaclor’s role in wound care. The emphasis on appropriate use, resistance prevention, and cost-effectiveness reflects a thoughtful, patient-centered approach that is too often overlooked in clinical practice. Thank you for highlighting the importance of matching antibiotic selection to clinical context rather than defaulting to broader-spectrum agents. This is the kind of education that improves outcomes and preserves the efficacy of our antimicrobial arsenal.
jennifer sizemore
I love how this post doesn’t just list facts-it explains why it matters. I’m a nurse and I’ve seen too many patients stop antibiotics because they "feel better." This is exactly the kind of info we need to share. I’m printing this out for our clinic bulletin. Thank you for taking the time to write this.
matt tricarico
Interesting. But let’s be honest-this is just glorified pharmaceutical marketing dressed up as clinical guidance. Cefaclor is a relic. The real story here is how lazy prescribing culture clings to outdated oral cephalosporins while ignoring newer, more targeted options. The cost argument is laughable-$25 is nothing when you factor in readmissions from failed therapy. This article is safe. And safe is the enemy of progress.
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