What you need to know about keflex (cephalexin)


Keflex (cephalexin) is a first-generation cephalosporin antibiotic used to treat confirmed and suspected bacterial infections of the respiratory tract, skin, bones, and urinary tract. This specific antibiotic is best used to treat gram-positive bacterial infections. It is available as capsules, tablets, and suspension (liquid) for oral administration.

Learn about medicine / Teresa Chiechi


Cephalexin is most commonly used to treat bacterial infections in acute otitis media, respiratory tract infections, infections of the skin and skin structures, bone infections, and infections of the genitourinary system. Specific bacterial infections include the following :

Acute otitis media :

  • Pneumococcus
  • Haemophilus influenzae
  • Staphylococcus aureus
  • Streptococcus pyogenes
  • Moraxella catarrhalis

Respiratory tract infections:

  • Staphylococcus aureus
  • Streptococcus pyogenes

Infections of the skin and skin structures:

  • Staphylococcus aureus
  • Streptococcus pyogenes

Bone infections:

  • Staphylococcus aureus
  • Proteus mirabilis

Urogenital tract:

Cephalexin is also used to prevent endocarditis and to treat tunnel or exit site infections in patients with peritoneal dialysis catheters .

Before drinking

Before taking cephalosporins, it is important to speak with your doctor about any drug allergies, including allergies to penicillin . Do not take this medicine if you are allergic to cephalexin or other cephalosporin antibiotics .

Other precautions and contraindications include :

  • Cephalexin interacts with numerous medications such as warfarin , metformin , probenecid, other antibiotics, and some vitamins.
  • It can increase the clotting time of the blood.
  • Be careful if you have liver or kidney disease.
  • Liquid cephalexin can interact with diabetes due to its sugar content.
  • Talk to your doctor about any history of intestinal problems.

Talk to your doctor about all the medications, supplements, and vitamins that you are currently taking.

Other cephalosporins

Keflex (cephalexin) is a first generation cephalosporin. Others include cephradine, cefadroxil, and cefazolin. Second-generation cephalosporins are more active against gram-negative bacteria. These include cefoxitin, cefotetan, cefuroxime, and cefprozil. Third-generation cephalosporins include ceftazidime and rocefin (ceftriaxone).


All indicated doses are indicated by the manufacturer of the drug. Check your prescription and talk to your doctor to make sure you are taking the correct dose.

Standard pediatric doses:

  • General dose: 25-50 milligrams (mg) / kilogram (kg) of body weight / day.
  • Otitis media: 75-100 mg / kg / day

Standard adult dosage:

  • Total dose: 250 to 500 mg every 6 hours. Maximum 4000 mg / day
  • Infections such as tonsillitis, skin infections, cystitis : 250 to 500 mg every 6 hours.

How to take and store

Follow these guidelines :

  • It can be taken with or without food.
  • Shake the liquid form before using.
  • Store liquid medicine in the refrigerator. Throw away unused medicine after two weeks.
  • Store tablets and capsules at room temperature.
  • Take it exactly as directed, even if you feel better.
  • Take the missed dose as soon as possible.
  • If your next dose is close to time, skip the missed dose and go back to your normal schedule.
  • Do not take two doses at the same time or take extra doses.
  • Do not change the dose of the medicine without consulting your doctor.

Side effects

As with all medicines, side effects can occur with cephalexin. Common and less serious side effects include :

Although they may be rare, cephalexin has side effects that require immediate medical attention, as they can be life-threatening :

It is also important to note that people can experience a severe allergic reaction, also known as anaphylaxis , when taking cephalexin. People allergic to cephalexin may experience the following symptoms: hives, difficulty breathing, including wheezing, swelling of the face, lips, tongue and / or throat.

Warnings and interactions

Remember this :

  • Long-term use can cause an overgrowth of insensitive organisms.
  • Cephalexin can cause false positive urine glucose results.
  • Do not stop taking the medicine until your doctor has taken all the doses or has told you to.
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