Cephalexin

Cephalexin is a prescription antibiotic licensed to treat and prevent bacterial infections. It comes in either capsule or liquid form in a variety of strengths. Infections that can be treated with the drug include bone infections, middle ear infections, and respiratory tract infections. It can also be used to prevent heart valve infections. Possible side effects of cephalexin include diarrhea, headache, and upset stomach.

What Is Cephalexin?

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

What Is Cephalexin Used For?

Cephalexin is licensed to treat a number of conditions. Some uses include:
 
  • Treatment of a bacterial infection, such as a:

 

 

  • Prevention of heart valve infections (bacterial endocarditis).
     
(Click What Is Cephalexin Used For? for more information.)
 
The drug is not effective against any infection caused by a virus, such as the flu, stomach flu, or common cold.
 

How Does It Work?

Cephalexin is part of a class of drugs called cephalosporins. It prevents bacteria from making and maintaining their cell wall. Without a cell wall, bacteria are vulnerable and ultimately perish.
 
Examples of other medicines in this class include Omnicef® (cefdinir) and Rocephin® (ceftriaxone).
 

Effects of Cephalexin

By affecting the cell wall of bacteria, cephalexin eventually causes the bacteria to die and stops the spread of infection in the body.
 

When and How Do I Take It?

General considerations for when and how to take the drug include the following:
 
  • The drug comes as a capsule or liquid suspension. It is usually taken two to four times a day, depending on your healthcare provider's instructions.

 

  • Cephalexin can be taken with or without food.

 

  • Drink a full glass of water with each dose.

 

  • It should be taken at the same time each day to maintain an even level of the medicine in your system.

 

  • For the drug to work properly, you have to take it as prescribed. Make sure that you complete your entire prescription, even if you start feeling better. This will ensure that the infection is completely treated.

 

  • Never take outdated cephalexin. Taking any outdated medication may cause serious problems because the intended effects often change after the medicine expires.
     

Dietary Considerations With Cephalexin

There are no dietary restrictions with this drug. If you have an upset stomach while taking it, however, try taking it with food or milk.
 

Dosing Information for Cephalexin

The dose 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 Cephalexin Dosage for more information.)
 

Side Effects of Cephalexin

As with any medicine, side effects are possible with cephalexin. 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 include, but are not limited to:
 
Less common but more serious side effects can also occur.
 
(Click Cephalexin Side Effects to learn more, including potentially serious side effects.)
 

Drug Interactions With Cephalexin

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

What Should I Tell My Healthcare Provider Before Taking It?

You should talk with your healthcare provider prior to taking this drug 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 cephalexin, 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 the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Cephalexin Precautions and Warnings to learn more, including information on who should not take the drug.)
 

What If I Take a Cephalexin Overdose?

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

How Should Cephalexin Be Stored?

Cephalexin capsules should be stored at room temperature. Cephalexin oral suspension should be refrigerated once it is in liquid form. The oral suspension expires 14 days after being prepared and should be discarded accordingly. Cephalexin products should be kept protected from light, moisture, and excessive heat.
 
As always, keep this medication and all other medications out of the reach of children.
 

What Should I Do If I Miss a Dose?

If you do not take your cephalexin 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 Cephalexin?

Numerous companies manufacture cephalexin. Some of them include:
 
  • Advancis Pharmaceuticals
  • Barr
  • Teva Pharmaceuticals
  • Ranbaxy Pharmaceuticals.
     

Are There Generic Versions Available?

Cephalexin is a generic medication. However, it is also available under a number of brand names. Some of these include:
 

Strengths of Cephalexin

The drug comes in a number of strengths and will vary somewhat, depending on who makes it. For cephalexin (which comes in capsules or liquid suspension), 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.
     
Biocef is also available as capsules and as a liquid. With Biocef, available strengths include:
 
  • Biocef 250 mg
  • Biocef 500 mg
  • Biocef suspension 125 mg/5mL -- each teaspoon (5 mL) containing 125 mg of cephalexin
  • Biocef suspension 250 mg/5 mL -- each teaspoon (5 mL) containing 250 mg of cephalexin.
     
Keflex is available as capsules and as a liquid. With Keflex, strengths 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.
     
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;
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