Keflex for UTIs: A Complete Knowledge About This Antibiotic

Aarohi Batra
Medically reviewed by
Dr. Kaushal

Review medical content on WOW Rx Pharmacy, so that accurate drug use information is easily accessible to everybody.
Dr. Akansha is a licensed Clinical Pharmacologist. She possesses remarkable knowledge in Pharmacovigilance, prescription analysis, drug information, and drug safety services. Additionally, she is a keen learner and an educator.

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keflex for uti

Keflex (Cephalexin) is a first-generation Cephalosporin used for treating various bacterial infections, including chronic UTIs.

Urinary Tract Infections are the prime cause of more than 60% of infections in adult women. 

Nearly 10 million people visit doctors yearly to find a cure for UTIs.

Therefore, knowing more about the details of Keflex has become a priority in treating UTIs.

Through this article, we will learn more about the details of Keflex and how it prominently work to treat UTIs.

It will help you find its necessity in treating and curing UTIs by eradicating the infection-causing bacteria.

How good is Keflex for UTIs

Keflex, or Cephalexin, is a good medicine for treating UTIs. 

According to a study on children suffering from acute lower Urinary Tract Infections, the immediate cure results were 90%, with no side effects recorded.

The medication course was for three days, and the dose was 25-50 mg/kg body weight.

However, following your doctor’s prescription and guidelines to use Keflex for UTIs is necessary. 

Keflex also efficiently treats upper respiratory, ear, skin, and bone infections. Consult your doctor for administering Keflex to cure these infections.

How does it treat UTIs

Keflex efficiently works by stopping the growth of infection-causing bacteria and curing UTIs.

This starts when Keflex inhibits the synthesis of bacterial cell walls. It causes few biological changes in the bacterial cell and results in cell autolysis (killing).

Through this inhibition, Keflex or Cephalexin successfully stops the growth of infectious bacteria and cures urinary diseases rapidly.

Recommended Article:
To know about other treatments of  UTIs, read the article UTI Treatment: Effective Strategies for Comfort and Relief at WowRxPharmacy and get a complete insight into its benefits.

Is Keflex FDA-approved for UTIs

Yes, Keflex is an FDA-approved medication for treating UTIs. 

It can effectively treat urinary infections if administered per a doctor’s prescription and necessary precautions. 

To get a rapid result, kindly ask your doctor about the steps to take while on medication. 

Also, tell your doctor about any previous illness, medication, genetic problems, and other necessary details to reduce the probability of serious consequences. 


Keflex for UTIs is generally available in oral pills. However, its generic form Cephalexin is available in oral capsules, liquid, and oral tablets for intake. 

Keflex for UTIs can be used in dosage as

  • For adults and patients above 18 to 64: Usually, patients are prescribed a dosage of 250 mg every six hours. 
  • For 15 to 17 years: Patients are administered 250 mg every six hours or 500 mg every 12 hours
  • Patients from 1 to 14 years: Children are prescribed medications with 25-50 mg/kg of body weight. However, the dose may depend on the severity of the disease and can increase based on the patient’s capability to handle it

Side effects of Keflex for UTIs

Joint painSource: SHOTPRIME
Joint pain

With the numerous benefits of Keflex in treating UTIs, there are a few side effects that may vary from person to person:

  • Stomach pain
  • Indigestion
  • Nausea
  • Diarrhea
  • Confusion
  • Irritation
  • Genital itching
  • Joint pain

Visit your doctor on facing any of the side effects mentioned above. 

If you are allergic to Penicillin, you may also have an allergy to Keflex.

Therefore, it is necessary to check for any allergy, such as an allergy to Penicillin, before taking first-generation Keflex for UTIs.  

If you are allergic to Penicillin, consult your doctor for medical approval. Negligence towards Penicillin can have severe consequences. 

Precautions while taking Keflex for UTIs

Keflex is an antibiotic that belongs to the class of medicine called Cephalosporin.

Cephalosporin was initially derived from a fungus.

In some people, it may cause allergy or other problems if continued for long. 

It is advised to consult your doctor and tell them about your previous allergies, drugs, vitamin pills, genetic disease, and other necessary details. 

People suffering from kidney-related problems are strictly prohibited from using Keflex.

Moreover, pregnant women should consult their doctors before active administration of Keflex for UTIs.

Food interactions

Multivitamins with minerals and Keflex should not be taken together. 

It is advised to take multivitamins with minerals for around three hours before administrating Keflex medicines.

Moreover, Zinc may inhibit the absorption of drugs in the bloodstream.

Therefore, consult your doctor for examination and carefully consume the foods for more efficient results. 

Disease interactions

Liver problem - medicine complicationsSource: Africa_Images
Liver disease (take recommended dosage)

Keflex may also interact with some diseases and cause health issues.

It can be prevented if proper measures are taken to avoid such complications as

  • Renal dysfunction
  • Colitis
  • Liver disease
  • Dialysis
  • Seizure disorders

Drugs interactions

There are about 35 drug interactions of Keflex. Take a look into these drugs and consult your doctor if you use any of the mentioned drugs.

This may improve the efficacy of Keflex and reduce the chances of serious implications.

  • Amoxicillin
  • Aspirin
  • Albuterol
  • Metformin
  • Lasix
  • Vitamin C
  • Vitamin B12


Keflex is an FDA-approved first-generation Cephalosporin treatment for UTIs and other body infections.

It also efficiently treats upper respiratory, ear, skin, and bone infections.

It works by stopping the bacterial cell from forming a cell wall and causing a cell rupture. In this way, it prevents bacterial growth and treats the disease.

However, there are a few side effects of Keflex that can be prevented by consulting your doctor and taking precautions.

You can avoid certain drugs and food interactions to increase the efficacy of the medication and avoid implications. 

Still, always consult your doctor before taking any medicine and immediately visit a doctor in case of severity.

Frequently Asked Questions

Is Keflex a good antibiotic for UTIs?

Yes, Keflex is an FDA-approved medication for treating UTIs and other infections. It stops the growth of infection-causing bacteria by preventing cell wall formation and effectively cures the disease. Always use medicine based on the doctor’s prescription for treatment and good results. 

How much Keflex should I take for UTIs?

The dosage of Keflex depends upon your age group. Generally, adults are prescribed to take 250 to 500 mg of Keflex every 6 to 12 hours, respectively. However, kids below this age may be defined with less dosage at regular intervals. Patients below 15 years are prescribed 25-50 mg/kg of body weight.

How long does Keflex take to work for UTIs?

According to a study on children suffering from acute lower urinary tract infections, the immediate cure results were 90%, with no side effects recorded. The course was for three days, and the dose was 25-50 mg/kg body weight. However, it is still advised to complete the full course for recovery.

What happens if Keflex does not work for UTIs?

If you have UTIs and Keflex does not work, the bacteria have developed antibiotic resistance. In this case, immediately consult your doctor and find the cure for this implication. You may face symptoms like nausea, frequent urination, pain, etc.

Is Keflex a strong antibiotic?

Keflex (Cephalexin)  may be considered a strong antibiotic for UTIs. Keflex works as a bactericidal (kills bacteria). However, Cephalexin is a broad-spectrum antibiotic that is effective on many bacteria. You should always consult your doctor before administering any medication.

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