Skip to Content

Keflex

Generic Name: cephalexin (sef a LEX in)
Brand Names: Keflex, Daxbia, Panixine Disperdose

Medically reviewed by Kaci Durbin, MD. Last updated on Jan 10, 2019.

What is Keflex?

Keflex (cephalexin) is a cephalosporin (SEF a low spor in) antibiotic. It works by fighting bacteria in your body.

Keflex is used to treat infections caused by bacteria, including upper respiratory infections, ear infections, skin infections, urinary tract infections, and bone infections.

Keflex may also be used for purposes not listed in this medication guide.

Important Information

You should not use Keflex if you are allergic to cephalexin or to similar antibiotics, such as Ceftin, Cefzil, Omnicef, and others. Tell your doctor if you are allergic to any drugs, especially penicillins or other antibiotics. Some people with penicillin allergies (including amoxicillin, ampicillin, and others) can have a fatal reaction with Keflex.

Tell your doctor if you have kidney disease, liver disease, a stomach or intestinal disorder such as colitis, or diabetes.

Take this medication for the entire length of time prescribed by your doctor. Your symptoms may get better before the infection is completely treated. Keflex will not treat a viral infection such as the common cold or flu.

Before taking this medicine

Do not use Keflex if you are allergic to cephalexin or to other cephalosporin antibiotics, such as;

  • cefaclor (Raniclor);
  • cefadroxil (Duricef);
  • cefazolin (Ancef);
  • cefdinir (Omnicef);
  • cefditoren (Spectracef);
  • cefpodoxime (Vantin);
  • cefprozil (Cefzil);
  • ceftibuten (Cedax);
  • cefuroxime (Ceftin); or
  • cephradine (Velosef), and others.

Tell your doctor if you are allergic to penicillin antibiotics prior to taking Keflex; these include drugs such as;

  • amoxicillin
  • ampicillin
  • dicloxacillin
  • oxacillin
  • penicillin G or penicillin V
  • piperacillin

To make sure Keflex is safe for you, tell your doctor if you have:

  • an allergy to any other drugs;
  • liver disease;
  • kidney disease; or
  • a history of intestinal problems, such as colitis.

Keflex is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

Cephalexin can pass into breast milk. Tell your doctor if you are breast-feeding a baby.

Tell your doctor if you are pregnant or breast-feeding.

How should I take Keflex?

Take Keflex exactly as it was prescribed for you. Follow all directions on your prescription label and read all medication guides or instruction sheets.

Do not use Keflex to treat any condition that has not been checked by your doctor.

Use Keflex for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses can increase your risk of infection that is resistant to medication. Cephalexin will not treat a viral infection such as the flu or a common cold.

Do not share Keflex with another person, even if they have the same symptoms you have.

This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using cephalexin.

Store the capsules at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, vomiting, stomach pain, diarrhea, and blood in your urine.

What should I avoid while taking Keflex?

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor before using anti-diarrhea medicine.

Keflex side effects

Get emergency medical help if you have signs of an allergic reaction to Keflex (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Call your doctor at once if you have:

  • signs of an allergic reaction such as difficulty breathing, swelling of the tongue, or skin rash;

  • severe stomach pain, diarrhea that is watery or bloody (even if it occurs months after your last dose);

  • unusual tiredness, feeling light-headed or short of breath;

  • easy bruising, unusual bleeding, purple or red spots under your skin;

  • a seizure;

  • pale skin, cold hands and feet;

  • yellowed skin, dark colored urine;

  • fever, weakness; or

  • pain in your side or lower back, painful urination.

Common Keflex side effects may include:

  • diarrhea;

  • nausea, vomiting;

  • indigestion, stomach pain; or

  • vaginal itching or discharge.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Keflex?

Metformin (a diabetes drug) and probenecid (an antibiotic) have been shown to interact with Keflex.

Other drugs may interact with Keflex, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Keflex only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Hide