When you’re prescribed Keftab (cephalexin), you might wonder if there’s a better option. Maybe your doctor switched you from another antibiotic, or you had a bad reaction. Maybe you’re just trying to understand why this one was chosen. The truth is, cephalexin isn’t the only antibiotic that works for skin, ear, or urinary infections-and it’s not always the best fit for everyone.
What is Keftab (Cephalexin)?
Cephalexin is a first-generation cephalosporin antibiotic. It’s been around since the 1960s and is still widely used today because it’s effective against common bacteria like Staphylococcus aureus and Streptococcus pyogenes. It’s taken orally, usually every 6 to 12 hours, and works by stopping bacteria from building their cell walls. Without a strong wall, the bacteria burst and die.
Keftab is often prescribed for:
- Skin infections like cellulitis or impetigo
- Ear infections (otitis media)
- Urinary tract infections (UTIs)
- Bone infections (osteomyelitis)
- Sometimes for respiratory infections if caused by susceptible strains
It’s not used for viral infections like colds or flu. And it’s not the first choice for pneumonia or sinus infections anymore-those often need broader coverage.
How Cephalexin Compares to Amoxicillin
Many people have taken amoxicillin before-maybe for a sore throat or ear infection. It’s one of the most common antibiotics worldwide. So how does cephalexin stack up?
Amoxicillin is a penicillin-type antibiotic. It’s broader in scope and works well against many Gram-positive and some Gram-negative bacteria. Cephalexin is narrower, but still strong against the same bugs that cause skin and ear infections.
Here’s how they compare:
| Feature | Cephalexin (Keftab) | Amoxicillin |
|---|---|---|
| Drug Class | Cephalosporin | Penicillin |
| Common Uses | Skin, ear, bone, UTI infections | Sore throat, ear, sinus, UTI, pneumonia |
| Allergy Risk | Low cross-reactivity with penicillin (5-10% risk) | High risk if you’re allergic to penicillin |
| Dosing Frequency | Every 6-12 hours | Every 8-12 hours |
| Effectiveness for Skin Infections | Excellent | Good, but less reliable for MRSA |
| Common Side Effects | Diarrhea, nausea, stomach upset | Diarrhea, nausea, rash (more common) |
If you’re allergic to penicillin, cephalexin is often the go-to alternative. But don’t assume it’s safe just because it’s not penicillin-about 5 to 10% of people with penicillin allergies react to cephalosporins too. Always tell your doctor about any past allergic reactions.
Cephalexin vs. Doxycycline
Doxycycline is a tetracycline antibiotic. It’s not used for the same infections as cephalexin. While cephalexin targets surface-level skin and ear bugs, doxycycline works deeper.
Doxycycline is often prescribed for:
- Acne
- Lyme disease
- Tick-borne illnesses
- Some respiratory infections like bronchitis
- Sexually transmitted infections like chlamydia
It’s not a direct substitute for cephalexin. If you have a skin infection and your doctor switches you to doxycycline, they’re likely treating something else-maybe acne that’s infected, or a bite that turned into a deeper infection.
Side effects of doxycycline include sun sensitivity, stomach upset, and yeast infections. It’s also not safe for children under 8 or pregnant women. Cephalexin doesn’t have those restrictions.
Cephalexin vs. Clindamycin
Clindamycin is another alternative, especially when there’s concern about MRSA (methicillin-resistant Staphylococcus aureus). Cephalexin doesn’t work against MRSA. Clindamycin does.
If you’ve had a skin infection that didn’t improve on cephalexin, your doctor might switch you to clindamycin. It’s also used for dental infections and abscesses.
But clindamycin has a serious downside: it can cause C. diff (Clostridioides difficile) infection. This leads to severe, sometimes life-threatening diarrhea. The risk is higher than with cephalexin.
Doctors usually avoid clindamycin unless they suspect resistant bacteria. It’s not a first-line option.
Cephalexin vs. Azithromycin
Azithromycin (Zithromax) is a macrolide antibiotic. It’s often called the “Z-Pack” because it’s taken over five days. It’s popular for respiratory infections like bronchitis and sinusitis.
But azithromycin isn’t great for skin infections. It doesn’t kill the same bacteria that cephalexin does. If you have a boil or infected cut, azithromycin won’t help much.
It’s also used for STIs like chlamydia. So if you’re switching from cephalexin to azithromycin, your doctor is likely treating something entirely different.
Azithromycin can cause heart rhythm changes in people with existing heart conditions. Cephalexin doesn’t have that risk.
When Cephalexin Might Not Be the Best Choice
Even though cephalexin is effective, it’s not perfect for everyone. Here are situations where another antibiotic is better:
- You’re allergic to penicillin: Cephalexin may still be okay, but your doctor might choose a non-beta-lactam option like clindamycin or azithromycin.
- You have a resistant infection: If your infection didn’t improve after 3-4 days, it might be MRSA or another resistant strain. Cephalexin won’t work.
- You’re treating a urinary tract infection caused by E. coli: While cephalexin can work, nitrofurantoin or trimethoprim are often preferred because they’re more targeted and have fewer side effects.
- You’re pregnant: Cephalexin is considered safe, but amoxicillin is often preferred because it’s been studied more in pregnancy.
- You’re on kidney dialysis: Cephalexin is cleared by the kidneys. If your kidney function is poor, your dose needs adjusting. Other antibiotics like clindamycin might be safer.
Side Effects and What to Watch For
Cephalexin is generally well-tolerated. Most people have mild side effects:
- Diarrhea (most common)
- Nausea or vomiting
- Stomach pain
- Headache
But rare but serious reactions can happen:
- Severe allergic reaction (rash, swelling, trouble breathing)
- C. diff infection (watery diarrhea, fever, stomach cramps)
- Liver problems (yellow skin, dark urine, fatigue)
If you develop diarrhea after starting cephalexin, don’t assume it’s normal. If it’s watery, bloody, or lasts more than 2 days, call your doctor. That could be C. diff.
What to Do If Cephalexin Doesn’t Work
Antibiotics aren’t magic pills. If you don’t feel better after 2-3 days, or if your symptoms get worse, you need to go back to your doctor.
Here’s what your doctor might do:
- Check if you’re taking the right dose. Some people need higher doses for skin infections.
- Take a swab or urine sample to test for resistant bacteria.
- Switch to a different antibiotic like clindamycin, trimethoprim, or ciprofloxacin.
- Order imaging if they suspect a deeper infection like an abscess.
Never stop antibiotics early just because you feel better. That’s how resistant bacteria grow. Finish the full course-even if your fever’s gone.
Over-the-Counter Alternatives? No.
There are no OTC antibiotics. Some people try herbal remedies, essential oils, or garlic supplements for infections. But none of these have been proven to kill bacteria like cephalexin does.
Using unproven treatments can delay real care. A small skin infection can turn into a hospital-level problem in days. Don’t risk it.
Final Thoughts: Choosing the Right Antibiotic
There’s no single "best" antibiotic. The right choice depends on:
- What kind of infection you have
- Your allergy history
- Your kidney or liver function
- Local resistance patterns (some bacteria are more resistant in certain areas)
- Whether you’re pregnant or have other health conditions
Cephalexin is a solid, reliable option for common infections. But it’s not the only one-and sometimes, it’s not the best. If you’ve had side effects or your infection didn’t improve, talk to your pharmacist or doctor. They can help you find the right match.
Antibiotics are powerful tools. Used right, they save lives. Used wrong, they cause more harm. Always follow your provider’s advice-not what you read online or what a friend did.
Is Keftab the same as cephalexin?
Yes. Keftab is a brand name for cephalexin. The active ingredient is identical. Generic cephalexin works the same way and costs less. Most people take the generic version unless there’s a specific reason to use the brand.
Can I take cephalexin if I’m allergic to penicillin?
Maybe. About 5-10% of people with penicillin allergies react to cephalosporins like cephalexin. If your allergy was mild (like a rash), your doctor might still prescribe it with caution. If you had a severe reaction (anaphylaxis, swelling, trouble breathing), they’ll likely avoid it and choose something else like azithromycin or clindamycin.
Does cephalexin cause yeast infections?
Yes, it can. Antibiotics kill good and bad bacteria. When the balance in your body shifts, yeast can overgrow. This can lead to vaginal yeast infections in women or oral thrush. If you notice itching, discharge, or white patches in your mouth, talk to your doctor. Antifungal treatments are available.
How long does cephalexin stay in your system?
Cephalexin has a half-life of about 1 hour in people with normal kidney function. That means half of it is cleared from your body in an hour. Most of it is gone within 8 hours. But you still need to take it every 6-12 hours to keep enough in your system to kill bacteria.
Can I drink alcohol while taking cephalexin?
Yes, you can. Unlike some antibiotics (like metronidazole), cephalexin doesn’t interact dangerously with alcohol. But drinking while sick isn’t smart-it can weaken your immune system and make side effects like nausea worse. It’s better to avoid it until you’re fully recovered.
Is cephalexin safe for children?
Yes. Cephalexin is approved for use in children as young as 1 year old. Doses are based on weight. It’s commonly used for ear infections and skin infections in kids. It doesn’t affect bone or tooth development like tetracyclines do.
Can cephalexin be used for a sinus infection?
Sometimes, but it’s not the first choice. Sinus infections are often caused by viruses. If they’re bacterial, they’re frequently caused by bacteria that cephalexin doesn’t cover well. Amoxicillin-clavulanate (Augmentin) is preferred because it covers a broader range of sinus pathogens.
What’s the most common mistake people make with cephalexin?
Stopping too early. People feel better after 2-3 days and think they’re cured. But the infection isn’t fully gone. That’s how resistant bacteria survive and spread. Always finish the full course-even if you feel perfect.
If you’ve been prescribed cephalexin and have questions, talk to your pharmacist. They can explain why this antibiotic was chosen and what to expect. Don’t guess. Don’t rely on forums or social media. Your health is too important for that.
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11 Comments
Anyone else notice how doctors just throw antibiotics around like candy? I got keftab for a pimple and now I got yeast infection from it. Like bro why not just let my body fight it? We're not in the 1950s anymore.
Look I get it cephalexin’s fine but let’s be real - most infections are viral and we’re just playing Russian roulette with our microbiome. I’ve seen people on antibiotics for a cold. That’s not medicine, that’s corporate greed dressed in white coats. 🤡
Cephalexin good for skin and UTI. Avoid if kidney issues. Clindamycin risk C. diff. Amoxicillin better for sinus. Simple.
PSA: if you get diarrhea after keftab don’t just ‘wait it out’ - if it’s watery and lasts more than 2 days call your doc. C. diff is no joke. I almost died from it last year. I’m lucky I didn’t need a colectomy.
Thank you for this breakdown. I’ve been on cephalexin twice and never knew why it was chosen over amoxicillin. My doctor just said ‘it’s fine.’ Now I actually understand the difference. This is the kind of info that helps people advocate for themselves.
My cousin took cephalexin for an ear infection and it worked great. But when she got a UTI next month, the doc switched her to nitrofurantoin and she said it was way gentler. Side effects were minimal. Maybe we need to stop defaulting to cephalexin for everything.
It’s important to remember that antibiotics are not interchangeable. The choice depends on bacterial susceptibility, patient history, and local resistance patterns. Self-prescribing based on Reddit advice can be dangerous.
We live in a world where a pill can fix everything but we’ve forgotten how to heal. Nature doesn’t work with antibiotics. It works with rest, hydration, and time. We’re poisoning ourselves with chemical crutches. The body is smarter than your doctor’s script.
Keftab’s like the Honda Civic of antibiotics - reliable, boring, doesn’t break down, gets the job done. But if you’re driving through a desert with a flat tire, you need a Jeep. Sometimes you need clindamycin or azithromycin. Don’t be afraid to ask your doc what’s really needed.
Side note: cephalexin can totally mess with your gut flora 😬 I got a yeast infection after 5 days and had to go on fluconazole. My gyno said it’s super common. Maybe they should hand out probiotics with these scripts? 🤔
Okay but what if your doc prescribed it and then ghosted you? I called 3 times after the diarrhea started and they said ‘it’s normal’ so I just suffered for 10 days. Now I’m terrified of every antibiotic. I swear I’m not crazy.