Cephalexin
Antibiotic
(Keflex)
By Dr. Karen Burgess

Brand name and formulations

• Cephalexin (generic)
• Keflex (human formula)
• Tablets, Capsules, and Liquid

What is Cephalexin?
Cephalexin is an antibiotic in the cephalosporin family that is a good choice for “gram positive” infections.  Considered a broad spectrum antibiotic, cephalexin is a good choice for many general infections of unknown origin.  Skin infections are commonly treated with cephalexin.

How is Cephalexin given and what if a dose is missed?
Cephalexin is typically prescribed for twice daily dosing.  If a dose is missed and it is less than 12 hours late, go ahead and give missed dose.  If it is within 12 hours of the next dose, skip a dose and resume regular schedule with next dose.  It may be helpful to give on a full stomach.

How should Cephalexin be stored?
The liquid formula should ideally be refrigerated and discarded after 14 days.

What is Cephalexin’s background?
Penicillin was developed in the late 1800’s and became popular in 1943 when it was used during World War II.  There are several limitations with the penicillin class which are addressed by the cephalosporin class of antibiotics.

What side effects are associated with Cephalexin?
Cephalexin may cause nausea and vomiting in some dogs.  Giving on a full stomach may help with these signs.  Some cats will develop a fever in response to cephalexin therapy.

What drugs should not be given with Cephalexin?
There are no specific drug interactions.

What follow up is necessary with Cephalexin use?
Medication should be used for some time after signs of illness or disease are gone.  Notify us if a refill is necessary