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Keflex

Keflex is commonly prescribed to treat and prevent bacterial infections. A few of the infections that the drug can treat are respiratory tract infections, sinus infections, and skin infections. It can also prevent heart valve infections. Keflex comes in both capsule and liquid form, and is usually taken two to four times a day. Common side effects include diarrhea, headache, and nausea.

 

What Is Keflex?

Keflex® (cephalexin) is a prescription antibiotic that is licensed to treat a number of common bacterial infections. It is part of a class of antibiotics called cephalosporins.
 

What Is Keflex Used For?

Uses for Keflex include the following:
 
  • Treatment for a bacterial infection, such as a:
o Respiratory tract infection (pneumonia, bronchitis, strep throat, or tonsillitis)
o Bone infection (osteomyelitis)
o Middle ear infection (otitis media)
o Sinus infection (sinusitis)
o Irritation of the prostate (prostatitis)
o Skin infection (cellulitis, folliculitis, or impetigo).
  • Prevention of heart valve infections (bacterial endocarditis).
     
(Click Keflex Uses for more information.)
 
Keflex is not effective against any infection caused by a virus, such as the flu, stomach flu, or common cold.
 

How Does Keflex Work?

Keflex prevents bacteria from making and maintaining their cell wall. Without a cell wall, bacteria are vulnerable and ultimately perish. As a result, the infection is kept from spreading within the body.
 
Examples of other medicines in this class include Omnicef® (cefdinir) and Rocephin® (ceftriaxone).
 

When and How Do I Take Keflex?

General considerations for when and how to take Keflex include the following:
 
  • Keflex comes as a capsule or liquid suspension. Keflex is usually taken two to four times a day, depending on your healthcare provider's instructions.
  • Keflex can be taken with or without food.
  • Drink a full glass of water with each dose.
  • Do not break, chew, or crush the Keflex capsules.
  • Keflex should be taken at the same time each day to maintain an even level of the drug in your system.
  • For Keflex to work properly, you have to take it as prescribed. Make sure that you complete your entire prescription of Keflex, even if you start feeling better. This will ensure that the infection is completely treated.
  • Never take outdated Keflex. Taking any outdated medication may cause serious problems because the intended effects often change after the medicine expires.
     

Dietary Considerations With Keflex

There are no dietary restrictions with Keflex. If you suffer from an upset stomach while taking Keflex, try taking it with food or milk.
 

Dosing Information for Keflex

The dose of Keflex that your healthcare provider recommends will vary, depending on a number of factors, including:
 
  • The medical condition you are being treated for
  • Your age
  • If you have decreased kidney function
  • Other medical conditions you may have
  • Other medications you are currently taking.
     
As always, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
 
(Click Keflex Dosage for more information.)
 

Side Effects of Keflex

As with any medicine, side effects are possible with Keflex. Not everyone who takes the drug will experience side effects, however. In most cases, if side effects do occur, they are minor, meaning that they require no treatment or are easily treated by your healthcare provider.
 
Common side effects of Keflex include but are not limited to:
 
Less common but more serious side effects are also possible.
 
(Click Keflex Side Effects to learn more, including potentially serious side effects.)
 

Drug Interactions With Keflex

Keflex can interact with a number of medicines (see Drug Interactions With Keflex).
 

Keflex: What Should I Tell My Healthcare Provider?

You should talk with your healthcare provider prior to taking Keflex if you:
 
  • Have kidney disease or kidney failure.
  • Are pregnant or thinking of becoming pregnant.
  • Are breastfeeding.
  • Will be having surgery.
  • Have any allergies. This includes allergies to Keflex, to other cephalosporins such as Omnicef® (cefdinir) and Rocephin® (ceftriaxone), to penicillin, or to other types of antibiotics.
 
Also tell your healthcare provider about all medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Precautions and Warnings With Keflex to learn more, including information on who should not take the drug.)
 

What If I Take a Keflex Overdose?

People who take too much Keflex may have overdose symptoms that could include but are not limited to:
 
If you happen to overdose on Keflex, seek immediate medical attention.
 

How Should Keflex Be Stored?

Keflex capsules should be stored at room temperature. Keflex oral suspension (liquid) should be refrigerated once it is in liquid form. The oral suspension expires 14 days after being prepared and should be discarded accordingly. Keflex products should be kept protected from light, moisture, and excessive heat.
 
Keep Keflex and all medications out of the reach of children.
 

What Should I Do If I Miss a Dose of Keflex?

If you do not take your Keflex as scheduled, take it as soon as you remember. If it is almost time for your next scheduled dose, skip the one you forgot and take your next dose instead. Never take a double dose!
 

Who Makes Keflex?

Keflex is manufactured by Advancis Pharmaceuticals.
 

Strengths of Keflex

Keflex comes in a number of strengths and will vary somewhat, depending on whether Keflex or generic cephalexin is being prescribed. Strengths for Keflex, which is available as capsules and as a liquid, include:
 
  • Keflex 250 mg
  • Keflex 333 mg
  • Keflex 500 mg
  • Keflex 750 mg
  • Keflex suspension 125 mg/5mL -- each teaspoon (5 mL) containing 125 mg of cephalexin
  • Keflex suspension 250 mg/5 mL -- each teaspoon (5 mL) containing 250 mg of cephalexin.
     
Generic cephalexin also comes in capsule or liquid form. Available strengths include:
 
  • Cephalexin 250 mg
  • Cephalexin 500 mg
  • Cephalexin suspension 125 mg/5mL -- each teaspoon (5 mL) containing 125 mg of cephalexin
  • Cephalexin suspension 250 mg/5 mL -- each teaspoon (5 mL) containing 250 mg of cephalexin.
     
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;