Antibiotics Home > Cephalexin Precautions and Warnings

An awareness of cephalexin precautions and warnings can help ensure a safe treatment process. Tell your healthcare provider if you are breastfeeding or about to have surgery before taking the drug. If you have severe kidney disease, your healthcare provider may give you a lower dose of the medication or not prescribe it at all. Cephalexin precautions and warnings also extend to people who are allergic to the drug, including any of its inactive components.

What Should I Tell My Healthcare Provider Before Taking Cephalexin?

You should talk with your healthcare provider prior to taking cephalexin (Keflex®, Biocef®) 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 medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.

Specific Cephalexin Precautions and Warnings

Some precautions and warnings to be aware of with cephalexin include the following:
  • Cephalexin can interact with certain medications (see Cephalexin Drug Interactions).
  • About 10 percent of people who are allergic to penicillins may also be allergic to cephalexin. Therefore, let your healthcare provider know if you are allergic to penicillin. Also, if taking cephalexin, tell your healthcare provider if you experience:
    • Unexplained rash
    • Itchy skin
    • Hives
    • Wheezing
    • Swelling of the throat
    • Difficulty breathing.
  • Cephalexin is considered a pregnancy Category B medication. This means that it has not been studied in pregnant women. When studied in animals, however, cephalexin showed no negative effects on the fetus. Talk to your healthcare provider before using cephalexin if you are pregnant.
  • If you have severe kidney disease, your healthcare provider may give you a lower dose of cephalexin or not prescribe this medication at all.
  • If you are nursing, it is known that cephalexin passes through breast milk. Therefore, you are recommended to stop nursing while taking cephalexin.
  • Many antibiotics, including cephalexin, have been known to cause pseudomembranous colitis (severe diarrhea) in some people. Contact your healthcare provider immediately if you experience:
    • Severe, watery diarrhea
    • Blood in your stools
    • Stomach pain
    • Low-grade fever.
  • Some people have been known to experience other infections while taking antibiotics. If you notice any unrelated symptoms, talk to your healthcare provider.
  • Taking cephalexin is known to increase the chance of developing vaginal yeast infections.
  • Never take outdated cephalexin. Taking any outdated medication may cause serious problems because the intended effects often change after the medicine expires.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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