Quick reality check: cefaclor’s peak fame was the 90s, but in 2025 it’s still on Aussie scripts-just not as the first pick for many common infections. If you’ve been handed a bottle or you’re googling it for your kid’s ear infection, you want straight answers: what it treats, how to take it right, and when there’s a better option. That’s what you’ll get here-no fluff, just safe, evidence-based guidance you can act on today.
- TL;DR: A second‑generation cephalosporin antibiotic used for ear, sinus, throat, skin, and some urinary infections-often as an alternative when first‑line drugs aren’t suitable.
- Typical adult dose: 250-500 mg every 8 hours; kids: 20-40 mg/kg/day split into 3 doses (don’t exceed 1 g/day). Take with food.
- Common side effects: diarrhoea, nausea, rash. Red flags: hives/swelling, severe diarrhoea, joint pains with rash/fever (serum sickness‑like reaction-see a doctor).
- Not ideal as first choice for many infections in Australia; amoxicillin/cephalexin often beat it for common cases. Check your specific diagnosis.
- Warfarin users: monitoring may be needed (INR can rise). Probenecid can raise levels. Avoid live typhoid vaccine during treatment.
What you probably need right now:
- Is cefaclor the right antibiotic for this infection?
- Exact dosing and timing for adults and kids, including missed-dose rules.
- Side effects to expect vs signs you need urgent care.
- How it compares to amoxicillin and cephalexin in 2025 Australia.
- What to do if you’ve got penicillin allergy, kidney issues, pregnancy, or breastfeeding.
What cefaclor does, who it’s for, and when it’s not the right antibiotic
Cefaclor is an oral second‑generation cephalosporin. It targets many Gram‑positive bacteria (like Streptococcus pyogenes) and some Gram‑negatives (like Haemophilus influenzae and Moraxella catarrhalis). In clinics here in Australia, it shows up for ear infections, sinusitis, strep throat, skin infections, and some urinary tract infections. It’s not the go‑to for all of these, but it can be a smart alternative when first‑line choices won’t work-say due to intolerance, local resistance patterns, or specific bug coverage.
How it fits into 2025 practice in Australia:
- Ear infections (otitis media): can be used, especially if amoxicillin isn’t suitable; some clinicians prefer amoxicillin-clavulanate or cefuroxime for beta‑lactamase producers.
- Sinusitis: reserved for bacterial cases with persistent/worsening symptoms; amoxicillin (or amoxicillin-clavulanate) is often first line.
- Strep throat: penicillin or amoxicillin is first choice. Cefaclor is an option if those aren’t tolerated.
- Skin infections: cephalexin usually wins; cefaclor is an alternative if broader coverage for some Gram‑negatives is wanted.
- UTIs: nitrofurantoin or trimethoprim are typical first‑line for uncomplicated cystitis; cefaclor is considered when those aren’t appropriate.
What it doesn’t cover well:
- MRSA and many hospital bugs-don’t expect it to touch those.
- Atypicals like Mycoplasma-macrolides or doxycycline are used there.
- Beta‑lactamase producers can reduce its effectiveness-your doctor considers this when choosing.
Australian context (Hobart included): prescribing follows Therapeutic Guidelines (Antibiotic), local resistance data, and PBS listings. Cefaclor products here include capsules (250 mg, 500 mg), modified‑release tablets (often 375 mg, branded “CD”), and oral suspensions (125/250 mg per 5 mL). Most suspensions need refrigeration after mixing and expire within 14 days-more on that below.
Therapeutic Guidelines: Antibiotic (Australia, 2024 update) puts stewardship first: “Use antibiotics only when bacterial infection is likely, choose the narrowest effective agent, and treat for the shortest effective duration.”
Who might avoid cefaclor:
- History of immediate anaphylaxis to penicillin or cephalosporins-cross‑reactivity is uncommon but real; avoid and discuss alternatives.
- Previous serum sickness‑like reaction (SSLR) to cefaclor-don’t rechallenge.
- Severe kidney impairment-dose interval adjustments are usually needed.
Pregnancy and breastfeeding (Australia, 2025): cephalosporins are generally considered safe in pregnancy; small amounts pass into breast milk and can cause loose stools or thrush in some infants. If you’re pregnant or breastfeeding, confirm with your clinician for your exact scenario (infection, trimester, other meds).
| Infection (typical outpatient) | Typical adult dose (AU) | Typical paediatric dose | Usual duration | First‑line status in 2025 (AU) |
|---|---|---|---|---|
| Strep throat (confirmed/suspected) | 250-500 mg every 8 h | 20 mg/kg/day in 3 doses (max 1 g/day) | 10 days | No (penicillin/amoxicillin first) |
| Acute otitis media | 500 mg every 8 h or 375 mg MR every 12 h | 40 mg/kg/day in 3 doses (max 1 g/day) | 5-7 days (child age‑dependent) | Alternative (amoxicillin often first) |
| Acute bacterial sinusitis | 500 mg every 8 h | 20-40 mg/kg/day in 3 doses | 5-7 days (if bacterial) | Alternative |
| Cellulitis/skin & soft tissue | 500 mg every 8 h | 20-40 mg/kg/day in 3 doses | 5-7 days (uncomplicated) | Alternative (cephalexin first) |
| Uncomplicated cystitis (female) | 250-500 mg every 8 h | N/A | 3-5 days | Not first‑line (nitrofurantoin/trimethoprim first) |
Note: Doses are typical ranges from Australian references; your prescriber fine‑tunes per bug, severity, and kidney function.
How to use cefaclor safely: dosing, timing, interactions, side effects
Getting the small stuff right is how you get better faster and dodge trouble. Here’s the practical, no‑nonsense way to take it.
Step‑by‑step for adults:
- Confirm the dose and schedule on your label. Standard: 250-500 mg every 8 hours; modified‑release (CD): often 375 mg every 12 hours.
- Take with food or milk to reduce nausea. Set phone alarms for 8‑hour spacing (e.g., 7am, 3pm, 11pm).
- Missed a dose? Take it if you remember within ~4 hours. If it’s close to the next dose, skip and resume. Don’t double up.
- Finish the prescribed course unless your clinician advises otherwise. Don’t save leftovers.
- Watch for red‑flag reactions (below). If they show up, stop and seek medical advice.
For kids (suspension):
- Dose is weight‑based. Common ranges: 20-40 mg/kg/day divided into 3 doses; do not exceed 1 g/day. Your script label should show mL per dose.
- Shake the bottle well before each use. Most cefaclor suspensions are kept in the fridge and discarded after 14 days-check the label.
- Use an oral syringe, not a kitchen spoon. If they spit it out immediately, you can usually redose; if it’s been a few minutes, do not redose-ask your pharmacist.
Kidney issues: with significantly reduced kidney function (e.g., CrCl < 30 mL/min), your prescriber may extend the interval (e.g., every 12 hours). If you’re on dialysis, timing often shifts to post‑dialysis dosing-get specific instructions.
Interactions that matter:
- Warfarin: antibiotics can reduce gut vitamin K and raise INR. If you’re on warfarin, let your prescriber know; extra INR checks may be needed.
- Probenecid: increases cefaclor levels; not usually combined unless intended.
- Live oral typhoid vaccine: effectiveness can drop if taken close together-space them well apart.
- Lab tests: cephalosporins can cause false‑positive urine glucose with copper‑reduction tests and a positive direct Coombs’ test.
Common side effects (usually mild):
- Diarrhoea or soft stools (most common), nausea, abdominal discomfort.
- Mild skin rash without other symptoms-still report it, especially if it worsens.
- Headache, dizziness (less common).
Serious or urgent signs-seek care fast:
- Hives, swelling of lips/tongue/face, wheeze, trouble breathing (possible immediate allergy).
- Severe or bloody diarrhoea, stomach cramps, fever (possible C. difficile infection).
- Widespread itchy rash with fever and joint pains around day 7-10, especially in children-this can be a known cefaclor‑linked serum sickness‑like reaction. Stop the drug and get assessed.
- Blistering rash or peeling skin (rare but serious).
Penicillin allergy questions:
- If you had a mild, delayed rash to penicillin years ago, many clinicians will still consider cephalosporins with caution.
- If you had immediate anaphylaxis to penicillin (hives in minutes, breathing issues), avoid cephalosporins like cefaclor unless an allergy specialist advises otherwise.
Alcohol? Moderate drinking isn’t known to cause a disulfiram‑type reaction with cefaclor, but alcohol can worsen dehydration if you already have diarrhoea. If you’re sick, hydrate and keep it easy.
Practical tips that reduce risk:
- Take doses evenly spaced; missed‑dose mistakes are a common reason antibiotics seem to “not work.”
- Swallow capsules whole with a full glass of water; MR tablets should not be crushed or chewed.
- Store suspension in the fridge (if the label says so) and mark the discard date on the bottle.
- If you’re not improving by 48-72 hours or you’re getting worse, reach out to your clinic-your bug may be resistant or the diagnosis may need a rethink.
Decisions, scenarios, and next steps: amoxicillin vs cefaclor, FAQs, troubleshooting
Choosing between common antibiotics isn’t about brand loyalty-it’s about the bug, the body site, allergies, and local resistance. Here’s how clinicians often frame it in Australia in 2025.
Cefaclor vs amoxicillin (big picture):
- For strep throat and many ear/sinus infections, amoxicillin remains first line: narrower spectrum, excellent activity against Streptococcus, and a long safety record.
- Cefaclor steps in when amoxicillin isn’t a fit (intolerance, prior failure, or need for a different spectrum). It has activity against some organisms that resist amoxicillin, but not universally.
- For skin infections, cephalexin often wins; cefaclor is considered if Gram‑negative coverage is desired.
- For uncomplicated UTIs, nitrofurantoin or trimethoprim usually beat both amoxicillin and cefaclor unless culture says otherwise.
Trade‑offs that matter to you:
- Side effect profile: cefaclor has a specific association with serum sickness‑like reactions in children (still uncommon but more than with many peers). If your child developed rash + joint pains after cefaclor before, avoid rechallenge.
- Dosing convenience: cefaclor often requires three times daily dosing; modified‑release helps but isn’t appropriate for every infection.
- Cost/access: in Australia, cefaclor is generally PBS‑listed; your out‑of‑pocket depends on concession status.
Handy decision heuristics (not a substitute for your doctor’s advice):
- If the infection is likely strep throat and you’re not allergic: penicillin or amoxicillin is simplest and effective.
- If your child has recurrent ear infections with suspected beta‑lactamase producers, clinicians may consider amoxicillin-clavulanate or cefuroxime; cefaclor is an alternative in some cases.
- If you’ve had immediate anaphylaxis to penicillin: avoid cefaclor; ask about macrolides, clindamycin, or other non‑beta‑lactams depending on the infection.
Mini‑FAQ:
- How fast will I feel better? Many people improve within 48 hours. If not, or if you worsen, check in with your clinician.
- Can I crush cefaclor? Don’t crush modified‑release tablets. Standard capsules shouldn’t be opened unless a pharmacist says it’s okay (they taste bitter).
- Is cefaclor a penicillin? No-it’s a cephalosporin. Some people allergic to penicillin can still take it, but severe penicillin allergy is a red flag.
- Can I take it with probiotics? If you want to try probiotics, separate by a few hours. Evidence is mixed; some people find they reduce diarrhoea.
- What if the suspension was left out overnight? If it should be refrigerated and sat out, ask your pharmacist whether to replace it-stability depends on time/temperature.
- Do I need food with it? It’s gentler with food and absorption is fine, so yes, pair it with meals.
Troubleshooting by scenario:
- Diarrhoea becomes severe or bloody: stop the antibiotic and seek medical care-risk of C. difficile is small but serious.
- Rash after day 7 with fever and sore joints (child or adult): think serum sickness‑like reaction. Stop and get seen promptly.
- Warfarin user notices nosebleeds or bruising: arrange an INR check; your dose may need tweaking during/after therapy.
- Missed multiple doses: don’t double to catch up. Restart the regular schedule and let your prescriber know if symptoms lag.
- No improvement at 72 hours: call your clinic. You may need culture tests, a different antibiotic, or a non‑antibiotic diagnosis (e.g., viral).
Safety note and why stewardship matters:
Antibiotic resistance is local and moving. In Tasmania and across Australia, prescribers lean on culture results and evolving guidelines. That’s why what worked for your neighbour isn’t necessarily right for you. Shortest effective duration and the narrowest effective drug aren’t buzzwords-they reduce side effects for you now and keep antibiotics working later.
Where this guidance comes from: Australian Therapeutic Guidelines: Antibiotic (2024 update), Australian Medicines Handbook (2025), NPS MedicineWise, and global resources like the CDC’s antibiotic safety notes. Those sources line up on the big points above: when to use cefaclor, how to dose, watch‑outs, and when to consider alternatives.
Next steps:
- If you already have a cefaclor script, read your label, set alarms, and take the first dose with food.
- If you’re not sure it’s the right drug, call your prescriber before starting-especially if you have a history of severe beta‑lactam allergy, are pregnant, or have kidney disease.
- Parents: record the time of each dose, store the suspension correctly, and note any rash/fever in a quick diary. It helps your doctor if a review is needed.
- On day 3, check in with yourself: better, same, worse? That one question often catches resistant bugs early.
You don’t need to memorise any of this. Save the page, follow your label, and use the checklists when you need them. If something feels off, reach out-early tweaks beat late regrets every time.
Sandridge Nelia
September 6, 2025 AT 05:20Just started my kid on cefaclor for ear infection - been using the suspension, fridge-stored, and it’s been fine so far. Took the first dose with a banana and some yogurt, no nausea. Fingers crossed it works better than amoxicillin did last time. Thanks for the clear dosing guide!
Mark Gallagher
September 6, 2025 AT 15:12You people need to stop using this outdated antibiotic. Cefaclor is a relic from the 90s. In 2025, Australia should be using cefdinir or ceftriaxone for otitis media - not this half-dead cephalosporin. If your GP prescribes this, ask for a second opinion. The guidelines you’re quoting are outdated.
Wendy Chiridza
September 8, 2025 AT 13:12Thanks for the detailed breakdown. I’ve been using cefaclor for my daughter’s recurrent sinus infections and it’s worked well when amoxicillin failed. The key is making sure the suspension is shaken well and stored cold. We mark the bottle with a Sharpie - 14-day expiry is non-negotiable. Also, the serum sickness risk is real - we’ve seen it before. Always watch for joint pain after day 7.
Pamela Mae Ibabao
September 9, 2025 AT 04:06Okay but let’s be real - cefaclor is basically the antibiotic version of a beige sweater. It’s not ugly, it’s not flashy, it just kinda… does the job. But why choose it when amoxicillin is cheaper, simpler, and doesn’t come with that weird serum sickness risk? I get it’s an alternative, but alternatives should be last resorts, not default options. Also, who still uses modified-release tablets? That’s just asking for confusion.
Gerald Nauschnegg
September 10, 2025 AT 21:59Hey I just got prescribed this yesterday and I’m freaking out because my friend’s kid had a rash after taking it. Is it really that common? I’ve got a 3-year-old and I’m terrified. I don’t want to be that parent who ruins their kid’s immune system with antibiotics. What’s the actual percentage of kids who get serum sickness from this? Like 1 in 100? 1 in 1000? Someone give me real stats.
Palanivelu Sivanathan
September 11, 2025 AT 00:39Ohhh my god… this post is like a sacred text from the temple of antibiotics… I feel the vibrations… cefaclor… it carries the energy of the 90s… the era of dial-up and Tamagotchis… and now it’s back… like a ghost… whispering through the Australian pharmacy shelves… the bacteria… they remember… they know… they’ve adapted… and we… we are still giving them cefaclor like it’s a love letter… but it’s not love… it’s desperation…
Joanne Rencher
September 11, 2025 AT 11:02Why is this even on the PBS? It’s just a lazy doctor’s way to avoid thinking. Amoxicillin is cheaper, better, and doesn’t come with side effects that sound like a horror movie. Also, who still uses suspensions? Just give them a pill. Kids can swallow pills. Stop coddling them.
Erik van Hees
September 11, 2025 AT 16:57Let me tell you something you didn’t know - cefaclor has a higher bioavailability than cephalexin in the middle ear. That’s why it’s still used for otitis media in Australia. You think it’s outdated? Nah. It’s just not marketed like the new fancy antibiotics. Also, if you’re worried about penicillin allergy, you’re probably overestimating cross-reactivity. It’s under 10% for non-anaphylactic cases. Read the data, not Reddit.
Cristy Magdalena
September 12, 2025 AT 05:16I took cefaclor for a UTI last year and it made me feel like I was slowly dissolving inside. My skin felt like it was crawling. I cried every night. I thought I was dying. My doctor said it was "just side effects." But I know. I KNOW. I’ve been traumatized. Don’t let this happen to you. If you feel even a little off - stop. Just stop. And scream into the void. I did. It helped.
Adrianna Alfano
September 13, 2025 AT 13:16Just wanted to say thank you for this. My daughter got cefaclor for her ear infection and I was so scared because I didn’t know what to watch for. You listed the red flags and I actually printed it out and taped it to the fridge. We’re on day 4 and she’s doing great. I also gave her probiotics 2 hours after each dose - no diarrhea. Small wins, right? 🙌
Casey Lyn Keller
September 15, 2025 AT 01:26Who wrote this? Is this a government psyop? Cefaclor is used because the pharmaceutical companies have deals with the PBS. They’re not telling you that cefaclor is cheaper to produce than newer drugs. The side effects? They’re covered up. You think serum sickness is rare? It’s underreported. The CDC knows. The WHO knows. But you? You’re still taking it with your banana.
Jessica Ainscough
September 16, 2025 AT 06:20This is the kind of post I wish I’d seen before my kid’s last antibiotic round. So clear, so practical. I’m saving this. Also, the part about setting alarms for doses? Genius. I used to forget and then double up. Now I’ve got a little sticky note on the fridge with the times. Small changes, big difference.
May .
September 17, 2025 AT 14:04Why does anyone still use cefaclor
Sara Larson
September 18, 2025 AT 08:36YESSSS this is exactly what I needed!! 🙌 I was stressing about the suspension storage and now I know to mark the date on the bottle!! Also the 48-72 hour check-in? BRILLIANT. I’m writing it on my calendar!! Thank you for being so clear and not making me feel dumb for asking questions!! 💖
Josh Bilskemper
September 19, 2025 AT 20:07This is a poorly curated summary. You’re citing Therapeutic Guidelines like they’re gospel. But the guidelines are written by committee and lag behind real-world resistance patterns. Cefaclor’s utility in Australia is declining. If you’re not using culture data, you’re just guessing. And guessing kills.
Storz Vonderheide
September 21, 2025 AT 10:40As someone who works in a rural pharmacy in Queensland, I see this a lot. Parents come in confused because the script says "375 mg MR" and they don’t know what MR means. We always explain it’s modified-release - once in the morning, once at night. We also give them a little card with the red flags printed on it. Small things make a big difference. Also - yes, refrigerate the suspension. Don’t leave it on the counter. I’ve seen it happen too many times.
dan koz
September 22, 2025 AT 10:47Man I just came from Nigeria and we don’t even use cefaclor here anymore. We use azithromycin for ear infections and ceftriaxone for everything else. This is like bringing a typewriter to a smartphone fight. But I guess Australia still clinging to old stuff because of bureaucracy. I mean… I respect the effort but… really? Cefaclor in 2025?
Kevin Estrada
September 23, 2025 AT 01:32Okay so I’m the guy who took cefaclor and then got a rash on day 9 and thought I was dying. Turns out it was serum sickness. I was in the hospital for 3 days. My joints hurt like I’d been hit by a truck. My mom cried. My dog looked at me like I’d betrayed him. I’m not mad. I’m just… disappointed. Like why didn’t anyone warn me? This post? This post could’ve saved me. So thanks. But also… why is this even still a thing?
Katey Korzenietz
September 23, 2025 AT 18:26Why is this even allowed? You're telling people to take it with food? Like it's a vitamin? This is a powerful antibiotic. You don't "take it with a banana". You follow the script. Or you don't take it. And if your kid gets a rash? You don't "watch it" - you go to the ER. You're normalizing dangerous behavior. This post is irresponsible.