Antibiotic Selection Calculator
Choose your scenario
Select the infection type and key factors to see recommended antibiotics
Recommended Antibiotic
Class: Cephalosporin (1st gen)
Dose: 500 mg every 6 hours
Cost: AU$10-15 per 30-tablet pack
Why this choice: Based on your selected infection type and factors, this antibiotic offers the best balance of effectiveness, safety, and cost for your scenario. See article section on decision criteria for more details.
Key considerations: Common side effects include GI upset and rash. Not recommended for beta-lactamase-producing organisms without combination therapy.
NOT medical advice. This tool provides general information only. Consult your healthcare provider for personal treatment decisions.
Key Takeaways
- Keflex is a first‑generation cephalosporin that works well for skin, bone and urinary‑tract infections.
- Amoxicillin is broader‑spectrum but vulnerable to beta‑lactamase‑producing bugs.
- Dicloxacillin targets penicillin‑resistant staph; useful when Keflex isn’t enough.
- Clindamycin covers anaerobes and some MRSA strains, but it can cause C. difficile colitis.
- Azithromycin offers convenient once‑daily dosing, yet it’s less effective for many gram‑positive infections.
What Is Keflex (Cephalexin)?
When doctors prescribe Keflex (Cephalexin), they’re giving a first‑generation cephalosporin that blocks bacterial cell‑wall synthesis. Approved by the FDA in 1979, it quickly became a go‑to for uncomplicated skin infections, ear infections, and urinary‑tract infections (UTIs). Typical adult dosing is 250‑500mg every 6hours for 7‑10days, though doctors adjust based on infection severity and kidney function.
Why Compare Alternatives?
Not every infection responds the same way. Bacteria can produce enzymes that neutralize certain drugs, or they may hide in tissues where a particular antibiotic can’t reach. Knowing the strengths and weak points of other common drugs helps you and your clinician pick the most effective, safest, and most affordable option.
Side‑Effect Profiles at a Glance
All antibiotics carry risks, but the nature of those risks varies:
- Keflex: mild GI upset, rash, rare allergic reactions.
- Amoxicillin: diarrhea, yeast overgrowth, hypersensitivity in penicillin‑allergic patients.
- Dicloxacillin: liver enzyme elevation, GI upset, possible neutropenia with prolonged use.
- Clindamycin: higher chance of Clostridioides difficile infection, metallic taste, rash.
- Azithromycin: QT‑prolongation in susceptible people, upset stomach, rare liver toxicity.
Decision Criteria: How to Choose the Right Drug
Use the following checklist when you’re deciding between Keflex and its alternatives:
- Infection type: Skin and soft‑tissue infections often respond well to cephalosporins; respiratory infections may need a broader‑spectrum agent.
- Pathogen susceptibility: If the lab reports a beta‑lactamase‑producing organism, avoid amoxicillin alone.
- Allergy history: Penicillin‑allergic patients usually can tolerate cephalosporins, but cross‑reactivity is possible.
- Convenience: Azithromycin’s once‑daily dosing may improve adherence.
- Cost & availability: In Australia, generic Keflex usually costs between AU$10‑15 per 30‑tablet pack, while azithromycin can be AU$20‑30.
- Resistance trends: Local antibiograms often show rising resistance to amoxicillin in community‑acquired pneumonia.
Side‑by‑Side Comparison Table
| Antibiotic | Class | Typical Use | Adult Dose (12h) | Common Side Effects | Approx. Cost (AU$) |
|---|---|---|---|---|---|
| Keflex | Cephalosporin (1st gen) | Skin, bone, UTIs | 500mg q6h (2×500mg per 12h) | GI upset, rash | 10‑15 |
| Amoxicillin | Penicillin | Respiratory, otitis media | 500mg q8h | Diarrhea, allergic rash | 8‑12 |
| Dicloxacillin | Penicillin‑derived | Staph skin infections | 250‑500mg q6h | Liver enzyme rise, GI upset | 12‑18 |
| Clindamycin | Lincosamide | Anaerobic infections, MRSA | 300mg q6h | C.difficile risk, metallic taste | 15‑22 |
| Azithromycin | Macrolide | Respiratory, STIs | 500mg day1, then 250mg daily x4 | QT prolongation, stomach upset | 20‑30 |
Real‑World Scenarios
Scenario 1 - Small cut that got infected: A 30‑year‑old with no drug allergies presents with cellulitis. Culture shows Staphylococcus aureus that’s not MRSA. Keflex is a solid choice because it’s cheap, taken four times daily, and hits the bug.
Scenario 2 - Uncomplicated pneumonia: A 65‑year‑old with hypertension develops cough and fever. Local antibiogram indicates high macrolide resistance, but the organism is likely Streptococcus pneumoniae. Amoxicillin (or amoxicillin‑clavulanate) works well unless the patient is allergic.
Scenario 3 - Post‑surgical wound infection with MRSA risk: The surgeon orders Clindamycin because it covers MRSA and anaerobes, even though it carries a higher CDI risk. The patient gets counseling on signs of severe diarrhea.
Scenario 4 - Travel‑related diarrhoea: A 28‑year‑old returning from Southeast Asia experiences dysentery. Azithromycin offers a single‑dose regimen and good activity against many travel‑related pathogens.
How Antibiotic Resistance Affects Your Choice
Resistance isn’t just a lab thing; it changes which drugs actually work. In Australia, the 2024 national surveillance report showed a 12% rise in beta‑lactamase‑producing bacterial infection strains that render amoxicillin ineffective. That’s why many clinicians now start with Keflex or a higher‑generation cephalosporin for skin infections.
Practical Tips to Avoid Common Pitfalls
- Finish the full course even if you feel better. Stopping early fuels resistance.
- Take the drug with food if it upsets your stomach, but don’t skip the dose because you think it’s “just a pill”.
- Inform your pharmacist about any other meds - especially antacids or iron supplements that can lower absorption of some antibiotics.
- Store tablets in a cool, dry place; heat and humidity can degrade potency.
- If you develop severe diarrhea, rash, or breathing trouble, seek medical help right away.
Frequently Asked Questions
Can I take Keflex if I’m allergic to penicillin?
Cross‑reactivity between penicillins and first‑generation cephalosporins like Keflex is low (around 2‑5%). Most penicillin‑allergic patients tolerate it, but it’s best to discuss your specific reaction with a doctor first.
Why is Amoxicillin sometimes less effective than Keflex?
Amoxicillin belongs to the penicillin class, which many bacteria defeat by producing beta‑lactamase enzymes. Keflex, as a cephalosporin, is more resistant to those enzymes, so it can clear some infections that amoxicillin can’t.
Is it safe to use Azithromycin for a child’s ear infection?
Azithromycin is approved for pediatric otitis media, but it’s only recommended when the likely bacteria are susceptible. Many pediatric guidelines still prefer amoxicillin because it’s cheaper and has a longer track record for ear infections.
What should I do if I miss a dose of Keflex?
Take the missed dose as soon as you remember, unless it’s almost time for the next one. In that case, skip the missed pill and continue with your regular schedule - don’t double up.
How long does it take for resistance to develop?
Resistance can emerge after just a few courses of inappropriate use. That’s why doctors stress completing the prescribed length and avoiding antibiotics for viral illnesses.
Teknolgy .com
October 14, 2025 AT 13:39Great, another glorified spreadsheet of drug prices 🙄.