9 Facts About Cephalexin (Keflex) For UTI & 12 Tips When Treating UTI With Antibiotics

I took Cephalexin for UTI twice, other times I was prescribed Macrobid and Cipro. To be frank, I tolerate antibiotics very well, but this doesn’t mean that I like them. However, antibiotics are sometimes a necessary evil.

First of all, make sure that antibiotics are the right choice. If you only have pain in your bladder and after urination but your urine is clear, antibiotics might not be the best solution.

If you see blood in your urine or it’s cloudy and has a strange smell, it could be a perfect case for antibiotics. Check out this $20 online prescription service to order Cephalexin for UTI. The service is licensed in 25 states and they’ll send an antibiotics prescription to your nearest pharmacy the same day.

Even if you do have a UTI, some doctors prefer to try a more natural solution first. Here is my interview with Dr. Wright, the first doctor who used D-Mannose in the USA in the 1980s, he also suggests that SSKI could be an option if D-Mannose didn’t work.

1Cephalexin (KEFLEX) & UTI: My Experience

I have had my share of UTIs several years ago. Fortunately, I was able to get rid of this chronic problem, mostly by relying on the special type of probiotics and some lifestyle changes.

If this is your first UTI and you are treating it with Cephalexin, it is not guaranteed that the UTI won’t come back.

Remember, the antibiotics will kill the bacteria that invaded your bladder, but antibiotics do nothing to address any of the underlying health conditions that caused a UTI in the first place.

If you do not want to experience the horrors of UTI again, make sure to implement smart prevention strategies, and do not rely solely on the antibiotics:

2Cephalexin For UTI: How Soon It’ll Work

By the time you take your first pill you are probably desperate for a relief and wonder how soon Cephalexin will work.

It should work pretty quickly.

I felt almost an immediate relief when taking Cephalexin for UTI symptoms.

  • Within an hour after taking the first pill the pain with urination subsided.
  • In a few hours, I no longer had blood in my urine.
  • By the next day, all my symptoms were completely gone.
Can you boost Cephalexin performance?

However, if you truly want Cephalexin to work, make sure to boost the performance of antibiotics with bacterial biofilm enzymes and diet that keeps your urine alkaline.

Haven’t heard about bacterial biofilms? In a nutshell, bacteria group together on the surface of your bladder and release slime to protect themselves from antibiotics.

Some naturopathic doctors use enzymes and small molecules (for example, NAC), that are thought to aid in breaking bacterial biofilms and killing pathogenic bacteria.

  • Ask your doctor about NAC supplements to potentially help destroy bacterial biofilms.
What to expect when taking Cephalexin?
  • Once you start taking antibiotics, you should feel better within the first 8-12 hours. However, make sure to finish all pills regardless of how well you feel.
  • If you are not feeling better or if your symptoms are getting increasingly worse, if you start having any flank pain or feel nausea and weakness, call your doctor.
  • Cephalexin might not work if you have a type of bacteria that are resistant to this antibiotic. However, in some cases, resistance is actually mistaken with bacterial biofilms.

3Cephalexin Could Increase The Risk Of Repeated UTIs

Cephalexin belongs to a category of cephalosporin antibiotics.

I recently came across a study that demonstrated that another drug from cephalosporin group (Cephadroxil) promotes vaginal colonization with Escherichia coli, the number one bacteria causing UTIs.

It’s probably not a stretch to assume, that Cephalexin could have a similar effect on the vaginal microbiome.

Unfortunately, if your vagina is colonized with E. coli, you are almost guaranteed repeated UTIs after sex. Healthy vaginas normally have an ability to deter E. coli bacteria and therefore play a key role in preventing UTIs.

If your vaginal health is compromised, your risk of chronic UTIs is higher.

4Cephalexin Could Promote Yeast Infection

Beneficial bacteria Lactobacilli are present in healthy vaginas and help to sustain acidic pH that deters pathogens and yeast.

Like any other antibiotic, Cephalexin will deplete your good bacteria and an yeast infection is an almost guaranteed side effect.

Unfortunately, once your good bacteria are depleted you are not only more prone to an yeast infection but also more vulnerable to your own E. coli bacteria. This, in turn, could lead to recurrent UTIs.

5Cephalexin Might Not Be Enough To Cure Chronic UTI

If this is not your first UTI, know one thing: you are not fighting a single-celled bacteria that are free-floating in your bladder. Most likely, you are fighting bacterial biofilms.

Cephalexin was approved by the FDA in January 1971. It slows or stops the growth of the bacteria cells, which bacteria need to survive.

However, bacteria eventually learn how to survive the antibiotic attack.

One of the methods is to team up, cover themselves with a slime and hide in deeper layers of your bladder lining. This allows bacteria to wait till you stop taking antibiotics and then renew their activity.

This bacterial method of defense called “bacterial biofilms”.

6I Took Antibiotics For UTI, But My Symptoms Still Persist

There are several scenarios why after taking antibiotics you could still feel some or all UTI-like symptoms.

First of all, you could be resistant to this particular medication. Second, it could be that you don’t even have a urinary tract infection. Obviously, it is critical to differentiate between these two options.

Here is my in-depth interview with urologist Dr. Lisa Hawes explaining the difference and what you could do about UTI symptoms that persist after antibiotic treatment.

7Cephalexin For UTI Can Lead To Bacterial Resistance

How many pills did your physician prescribe you?

  • Is this your first UTI?
  • Did you have any flank pain?
  • How long have you been experiencing your symptoms?
  • Can you try NSAIDs instead to relieve the symptoms while your body is fighting the infection?

Keep these questions in mind to discuss the length of antibiotic treatment with your physician.

A systematic review of 15 studies, including 1644 women aged over 75 years, concluded that short courses of antibiotics (varying from 3 to 6 days, depending on the antibiotic chosen) are as effective as long courses (7–14 days) for treating uncomplicated cystitis in older women.

The longer the duration of treatment, the higher your chances to develop an antibiotic-resistant bacteria.

However, do not shorten the prescribed course yourself and always consult with your prescribing physician.

8Frequent Side Effects Of Cephalexin

Personally, when taking Cephalexin for UTI I tolerated this antibiotic well.

However, mild side-effects are possible. Besides the yeast infection, the top three concerns of the patients on Treato, when taking Cephalexin are:

  • Allergies (most reported),
  • Thrush,
  • Nausea.

Other possible side effects include:

  • Diarrhea,
  • Dizziness, feeling tired,
  • A headache, joint pain,
  • Vaginal itching or discharge.

9Other Antibiotic Options Besides Cephalexin For UTI:

10Cephalexin And Pregnancy

There are no conclusive studies of using cephalexin in pregnant women.

But from what we know so far, Cephalexin is shown to be very effective and complications to mother and child are very rare.

11Be Careful If Allergic To Penicillin

According to a study published in Journal of investigational allergology and clinical immunology, if you are allergic to penicillins your chances to be allergic to cephalexin are about 11%.

However, later, other researchers debunked this “myth” by proposing that a history of penicillin allergy is a general risk factor to be allergic to any antibiotics and is not specific to cephalosporins.

1212 Tips When Treating UTI With Antibiotics

  1. Take antibiotics regularly

    You need to make sure to take one pill every 12 hours (unless prescribed otherwise) to support a constant level of antibiotics in your body.

    It is better to take the first pill sometime between 7-10 (a.m or p.m.).

    When treating my first UTI infection I took the first pill at 3 p.m. For the following 7 days, I had to set my alarm for 3 a.m. in the morning to take my night dose. Not fun!

  2. Take pills on time

    Once you take your first pill, set your phone timer for 12 hours. Repeat it every time you take a pill till you are done.

  3. Plan ahead

    Make sure to take your pills to work! For example, I separated mine into two containers so that I would always have some in my purse for the 3 p.m. pill and the rest would be by my bed for the 3 a.m. dose.

  4. Take all pills

    To clear up your infection completely, take antibiotics for the full course of treatment. Keep taking it even if you feel better in a few days.

    I had no symptoms just a few hours after the first pill.

    However, if you stop taking the antibiotics early you’ll increase your chances of a repeated infection and antibiotic resistance.

  5. Do not take extra

    If you forget and miss a dose, take the pill as soon as you remember. Skip the missed dose if it is almost time for your next one. Do not take extra medicine to make up for the missed dose.

  6. Stay sober

    It’s better to avoid alcohol. Sometimes it can worsen the side effects, sometimes it can affect the effectiveness of a drug.

    Because your liver is already under serious pressure to deal with the infection and the antibiotics, you do not want to overwhelm it with alcohol.

  7. Support your vaginal and bladder flora

    Start on a course of probiotics right away and plan for one more right after your treatment.

    Studies show that if you take probiotics while taking the antibiotics your beneficial flora will recover to its normal state faster and you are less likely to develop an yeast infection.

    To summarize, wait couple hours if possible to take your probiotic pill, do not take it at the same time as antibiotics and take special probiotics for 30 more days after you are done.

  8. Revitalize your microbiome after

    Continue with more probiotics after you finish your course of antibiotics.

    Make sure to buy special kind of probiotics containing beneficial vaginal bacteria. This will help you to prevent infections in the future.

  9. Watch out for serious side effects

    Do read the potential side effect of the antibiotics that your physician prescribed you.Let your doctor know if you develop diarrhea or vomiting.

    Some antibiotics (doxycycline, tetracycline, ciprofloxacin, levofloxacin, ofloxacin, trimethoprimcould also make your skin sensitive to the sun.

  10. Avoid Cipro

    If your doc prescribed you Cipro, ask him/her if you can start with an alternative option.

    Since 2016 FDA does not recommend prescribing Cipro for uncomplicated UTIs, but too many physicians still do not know. Make sure you are your own advocate.

  11. Take NAC supplements

If you are suffering from recurrent UTIs, learn about fighting microbial biofilms. Some naturopathic doctors use NAC supplements in hope to help destroy the slime that bacteria produce to hide from antibiotics and your immune system’s response.

12. Take D-Mannose with antibiotics

Currently, there is no information about D-Mannose interaction with antibiotics or any other drugs.

If you are considering to boost your antibiotic treatment, I’d give D-Mannose a try. After all, D-Mannose is simply a sugar.

What type of antibiotics have you tried? Leave me a comment, join our Facebook group. I’d love to hear from you.

My Most Popular UTI Guides

  1. 8 Holistic Strategies To Prevent UTI
  2. 7 Unexpected Facts About Vaginal Discharge And UTI
  3. Oral Sex And UTI: All You Need To Know
  4. Can I Get a UTI From My Partner?
  1. Using antibiotics responsibly: right drug, right time, right dose, right duration.
  2. Antibiotic duration for treating uncomplicated, symptomatic lower urinary tract infections in elderly women.
  3. Cephadroxil promotes vaginal colonization with Escherichia coli.
  4. Cross-reactivity and Tolerability of Cephalosporins in Patients With Cell-Mediated Allergy to Penicillins
  5. Treatments for symptomatic urinary tract infections during pregnancy


  1. I’ve had two rounds of Cephalexin and my UTI came back 2 days after the second course. When I was younger I had UTI’s often – I haven’t had one for years until this! And I’ve never had one so resistant to antibiotics. I’d rather not take another course, but will be open to it with an NAC molecule as well after reading the above. I wish there was a natural remedy – if there is, can you let me know? Looking forward to your reply.

    • Hi Madison, the only FDA approved method of treating UTIs is unfortunately antibiotics. However, you can read about various supplementations here. Join our FB group if you’d like to chat with other folks about the issue at hand. Best wishes,

    • There are many reasons why you could experience a UTI once again in such a short period of time. I’m curious to know what the results of the test. Best of luck,

  2. I was prescribed this on Aug 30 for UTI that had me unable to walk because of the pain in my back. I’m to take 2 every 12 hours. It took almost to day 6 to feel completely releived. I’ll finish the next 4 days. No side effects outside of very bad bloating. I’m using a probiotic that I’ll probably continue. Thanks for the very informative article.

    • Danielle, sounds like your infections spread to your kidneys and I’m glad to hear that you are feeling better. Make sure to choose right probiotics and see if you could take it for at least one month after you are done with the treatment. Best wishes,

  3. Just started Cephalexin and I accidentally took the second pill 3 hours after taking the first one! Will this affect anything? How fast will it start working? Seems like it flared up my itching/urge instead of settling it down. Is it normal ?

    • Hi Pris,
      Sorry I left you hanging, it was my wedding weekend so I disconnected.
      1) IMHO (and I’m not a doctor to provide a medical advice, so ask your doc): Taking too much at short intervals is not the worst mistake. Personally, I wouldn’t worry about it, and would try to keep 12 hours intervals going forward.
      2) “How fast” is very individual, but for me it worked within 2 hours after the first pill. Hopefully already worked for you! If not, let your doc know.
      3) Depends on what is itching 🙁 Itching is not really a common symptom of a UTI, if you have itching it could be anything ranging from an STD to an allergic reaction. Do tell your doc!
      Best wishes and feel better soon,

  4. will the itching inside stop after I finish my meds 🙁 its horrible
    I started taking Sunday its Tuesday now and have to take it 4 times a day for 3 days

    • Hey Nita!
      That’s an interesting side-effect, sorry must be annoying. Did you tell your doc? Try taking probiotics, see if this helps.

  5. I am taking this for a UTI and wowser it is making me feel like a zombie.I feel so drained and no energy.I have 1 to go tonight and 1 twice a day for next two days.Any hints on when to take it to cause the least chaos to my day as i have to work and seriously dont think i will cope if i take them at work.Work is 9am-5pm.Anyone taken them just at night so no side effects during the day.

    • Hey Ana, sorry to hear you are not taking it well. One more day to go!
      Talk to your doc but I don’t think he would change anything right now. Unfortunately you have to take each pill 12 hours apart to support the level of the antibiotic in your blood, there is no way around that.
      Best wishes,

  6. Hi, I am 9 weeks’ pregnant. I was prescribed Cefalexin (Keflex) 500mg x3 daily. Unfortunately 7 days later I still have symptoms. I am now on Co-Amoxiclav x3 daily. Fingers crossed, but wouldn’t wish this misery on anyone. I haven’t slept for a week….

    • Hi Jaimie,
      I’m so sorry to hear! Wish you and your baby to get through this as quick as possible. Just FYI, when on antibiotics you can still add D–Mannose to your treatment to see if it can speed up the recovery. Make sure to follow your physician’s prescription and finish all the antibiotic pills.
      Hopefully you’ll be over the hump in no time! Plan to double down on the preventive measures once you are healthy!


Please enter your comment!
Please enter your name here