Generic Keflex

Common use

Keflex is attributed as antibiotic of cephalosporins group which act against bacteria preventing formation of their cell walls. It is enough resistant to penicillinases of gram positive microorganims but can be destroyed by beta-lactamases of gram negative ones. It shows broad spectrum activity against gram positive microogranisms such as Staphylococcus, Staphylococcus epidermidis; Streptococcus, Corynebacterium diphtheriae, Clostridium, Actinomyces israelii, Bacillus anthracis, gram negative microorganisms like Escherichia coli, Klebsiella, Proteus mirabilis, Neisseria gonorrhoeae, Neisseria meningitidis, Shigella, Salmonella. Common infections that are treated with Keflex include infections of the middle ear, tonsils, throat, larynx (laryngitis), bronchi (bronchitis) and pneumonia as well as in urinary tract, skin, and bones.



Dosage and directions

The dose of Keflex for adults is 1 to 4 grams in divided doses. The interval between doses may be 6 or 12 hours depending on the infection.



Precautions

Before using Keflex, tell your doctor if you are allergic to any drugs (especially penicillins), have kidney or liver disease, a stomach or intestinal disorder such as colitis, and diabetes.



Contraindications

Hypersensitivity to Keflex, cephalosporins (Ceclor, Duricef, Omnicef, Spectracef, Suprax, Cefzil, Fortaz, Ceftin) and beta-lactamase antibiotics. Cautiousness should be exercised in patients with kidney disorder, pseudomembranous colitis, pregnancy, breastfeeding and babies younger than 6 month.



Possible side effect

Most common side effects may include signs of allergy (hives, rash, swelling of face and tongue), seizure, fever, sore throat, and headache with a severe blistering, peeling, and red skin rash, pale or yellowed skin, dark colored urine, fever, hallucinations, confusion or weakness, easy bruising or bleeding, unusual weakness, confusion, agitation, decreased or absent urination. In case of serious and persistent side effects listed above seek for immediate medical help.



Drug interaction

Inform your doctor about all medications you take and especially about live vaccines, probenecid. Keflex may decrease the effectiveness of combination-type contraceptive pills. This medication is able to show false positive results with certain diabetic urine testing products. Keflex increases effects of indirect anticoagulants, polphenilbutazone, furocemide. Salicylates and indomethacin slow excretion of cephalolexin by kidneys. Medications decreasing secretion in renal tubules increase concentration of the medication blood serum and slow down its excretion.



Missed dose

If you missed a dose take it as soon as you remember. If it almost time of your next dose just skip it and return to your regular schedule. Never double dose this medication.



Overdose

In case of serious and persistent symptoms of nausea, vomiting, stomach pain, diarrhea, and blood in your urine consult your doctor about medical attention.



Storage

Store at room temperature between 59-77 degrees F (15-25 degrees C) away from light and moisture, kids and pets. Do not use after expiration term.



Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care adviser or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Clinical Verification

Last Clinically Updated: August 15, 2026

Written By

Dr. Elena Vance, PharmD

Clinical Specialist in Neuropharmacology

Fact Checked By

Marcus Thorne, MS

Biomedical Data & FDA Label Verification

Medically Reviewed By

Dr. Arthur Campbell, MD

Board-Certified Psychiatrist (ABPN)