Keflex for UTI: How to treat UTI with Cephalexin

Keflex (Cephalexin) for UTI
Medically reviewed by Dr. Devindra Bhatt


Keflex, known as Cephalexin, is an antibiotic, particularly renowned for its efficacy in combating urinary tract infections (UTIs). UTIs, caused by bacteria invading the urinary system, can lead to discomfort and complications if left untreated.

With its potent bactericidal properties, Keflex is a cornerstone in treating UTIs, offering a reliable solution for individuals seeking swift relief and recovery. In this blog, we delve into the nuances of Keflex as a therapeutic agent, shedding light on how this medication plays a pivotal role in effectively treating urinary tract infections.

This blog provides information about the mechanisms, benefits, and considerations surrounding Keflex to empower yourself with the knowledge necessary for managing and overcoming UTIs.

Is Keflex (Cephalexin) effective for UTI?

Yes, Keflex (Cephalexin) is a common treatment option for urinary tract infections (UTIs). As an antibiotic falling under the cephalosporin class, it is frequently employed in addressing bladder and kidney infections. Keflex is a prescription for various bacterial infections, including UTIs. 

How is UTI treated using Keflex (Cephalexin)?

Keflex (cephalexin) proves its effectiveness by inhibiting the growth of bacteria that cause the infection. It is classified under cephalosporins, commonly prescribed antibiotics for bladder and kidney infections. If you stick to the prescribed full course and take ample fluids during the treatment, Keflex helps halt the growth of bacteria responsible for the infection.

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What is Keflex dosage for UTI?

Keflex (cephalexin) is prescribed at 250 mg orally every 6 hours or 500 mg every 12 hours for seven days. The doctor may adjust the dosage based on infection severity and patient history. 

It is critical to complete the prescribed course and drink plenty of fluids. Keflex, also known as cephalexin, is a cephalosporin antibiotic commonly used to treat bladder or kidney infections.

How does Keflex (Cephalexin) work against UTIs?

Keflex (Cephalexin) combats UTIs by hindering the growth of infection-causing bacteria. Cephalexin disrupts bacterial cell wall growth as part of the cephalosporin class, a group of antibiotics prevalent in treating bladder or kidney infections. This interruption prevents bacterial replication, contributing to eliminating the bacteria responsible for the infection.

How long does it take for Keflex to start working against a UTI?

Many individuals experience relief from UTI symptoms within a day or two of starting Keflex (Cephalexin) treatment. It is crucial to adhere to the full treatment course, usually lasting no more than seven days, even if symptoms subside.

Can Keflex be used for recurring UTIs?

Keflex (Cephalexin) is an option for managing recurrent UTIs and is often prescribed as a first-line antibiotic due to its effectiveness. Cephalexin is available in various forms, like capsules, tablets, or liquid suspension, with treatment courses ranging from 5 to 14 days.

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Can Keflex be used during pregnancy for UTI treatment?

According to the American Academy of Family Physicians, oral nitrofurantoin and cephalexin are good antibiotic choices for UTI treatment in pregnant women with asymptomatic bacteriuria and acute cystitis.

However, if Cephalexin is used, it must be stopped four weeks before delivery. It is important to note that the use of any medication during pregnancy should be discussed with a healthcare provider to weigh the benefits and risks.

Can Keflex be used for pediatric UTI treatment?

Yes, Keflex (Cephalexin) is suitable for pediatric UTI treatment. Children typically receive a recommended dosage of 25 to 50 mg per kg daily, divided every 6 to 12 hours, spanning 5-14 days.

The antibiotic selection should be customized based on the child’s age and clinical severity, considering the potential for antibiotic resistance in empiric therapy. Alternatives like Trimethoprim/Sulfamethoxazole, Amoxicillin/Clavulanate, Cefixime, Cefpodoxime, and Cefprozil are common for pediatric UTI treatment.

Sticking to your doctor’s guidance, completing the full course, and minimizing nephrotoxic drug use is crucial for optimal outcomes.

What are the considerations for children using Keflex (Cephalexin)?

Considerations for the use of Keflex (Cephalexin) in children include the following aspects:

  1. Children receive 25 to 50 mg per kg per day, divided every 6 to 12 hours, for 5 to 14 days. Dosage is weight-dependent, requiring sticking to the doctor’s guidance for the entire treatment course.
  1. Keflex is safe and effective for children, but the antibiotic choice should align with age, clinical severity, and awareness of potential resistance during treatment.
  2. Keflex is unsuitable for those hypersensitive to Cephalexin or cephalosporins and is contraindicated in penicillin-allergic patients due to heightened allergic reaction risk.
  1. Available as an oral capsule or suspension, Keflex should be stored and administered per guidelines, considering the child’s age and weight.
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How can I prevent UTIs after completing a course of Keflex?

Upon completing a Keflex course for UTI, adopt preventive measures for future instances, such as:

  1. Follow proper urination and bowel movement practices, including timely bathroom visits, front-to-back wiping, and post-sexual intercourse urination.
  2. Regularly drink water to flush out bacteria and decrease UTI risk.
  3. Choose showers over baths, as bacteria thrive in warm water, and certain bath soaps may irritate the urinary tract.
  4. Do not use scented or irritating genital products to maintain natural balance and prevent UTIs.
  5. After a thorough discussion, consult a healthcare provider for potential continuous antibiotic prophylaxis, especially for recurrent UTIs.
  6. Discuss the potential benefits of cranberry products in reducing recurrent UTI risk with a healthcare provider.
  7. Ensure consultation with a healthcare provider to tailor these preventive measures to your health and medical history.
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What are the consequences of missing multiple doses of Keflex during UTIs?

Skipping multiple doses of Keflex in UTI treatment may cause the infection to resurface and worsen. Completing the prescribed full course, usually within seven days, is important for complete eradication.

In case of missed doses, consult your healthcare provider for guidance. Skipping doses increases the risk of antibiotic resistance, a concerning issue.

When should I see a doctor?

When using Keflex for a UTI, consult your doctor immediately if severe or enduring side effects arise, symptoms do not improve, or if signs of an allergic reaction like rash, itching, swelling, or breathing difficulties occur. If pregnant, inform your doctor for careful monitoring. Adhere to your doctor’s guidance, avoiding premature discontinuation to prevent the infection from spreading.

Your Doctors Online uses high-quality and trustworthy sources to ensure content accuracy and reliability. We rely on peer-reviewed studies, academic research institutions and medical associations to provide up-to-date and evidence-based information to the users.

  • Seneca, H., A. Uson, and P. Peer. “Cephalexin in urinary tract infections.” The Journal of Urology 107, no. 5 (1972): 832-834.
  • Herman TF, Hashmi MF. Cephalexin. [Updated 2023 Aug 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from:

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