Cephalexin

Generic name: Pronounced as (sef a lex' in)
Brand names
  • Keflet® Tablets
  • Keflex®
  • Keftab® Tablets
  • Panixine® Disperdose
Click on drug name to hear pronunciation

Medical Content Reviewed By HelloPharmacist Staff

Last Revised - 06/15/2016

Cephalexin is used to treat certain infections caused by bacteria such as pneumonia and other respiratory tract infections; and infections of the bone, skin, ears, , genital, and urinary tract. Cephalexin is in a class of medications called cephalosporin antibiotics. It works by killing bacteria.

Antibiotics such as cephalexin will not work for colds, flu, or other viral infections. Using antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.

Cephalexin comes as a capsule, tablet, and suspension (liquid) to take by mouth. It is usually taken with or without food every 6 or 12 hours for 7 to 14 days, depending on the condition being treated. Take cephalexin at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take cephalexin exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Shake the liquid well before each use to mix the medication evenly.

You should begin to feel better during the first few days of treatment with cephalexin. If your symptoms do not improve or get worse, call your doctor.

Continue to take cephalexin until you finish the prescription even if you feel better. If you stop taking cephalexin too soon or skip doses, your infection may not be completely treated and the bacteria may become resistant to antibiotics.

Cephalexin is also sometimes used for certain penicillin allergic patients who have a heart condition and are having a dental or upper respiratory tract (nose, mouth, throat, voice box) procedure, in order to prevent them from developing a heart valve infection.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Before taking cephalexin,

  • tell your doctor and pharmacist if you are allergic to cephalexin; other cephalosporin antibiotic such as cefaclor, cefadroxil cefazolin (Ancef, Kefzol), cefdinir, cefditoren (Spectracef), cefepime (Maxipime), cefixime (Suprax), cefotaxime (Claforan), cefotetan, cefoxitin (Mefoxin), cefpodoxime, cefprozil, ceftaroline (Teflaro), ceftazidime (Fortaz, Tazicef, in Avycaz), ceftibuten (Cedax), ceftriaxone (Rocephin), and cefuroxime (Zinacef); penicillin antibiotics; or any other medications. Also tell your doctor if you are allergic to any of the ingredients in cephalexin capsules, tablets, or suspension.Ask your pharmacist for a list of the ingredients.

  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: anticoagulants ('blood thinners') such as warfarin (Coumadin, Jantoven); metformin (Fortamet, Glucophage, Glumetza, Riomet, in Glucovance, Invokamet, others); and probenecid (Probalan). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.

  • tell your doctor if you have or have ever had any kind of allergies, gastrointestinal disease (GI; affecting the stomach or intestines), especially colitis (condition that causes swelling in the lining of the colon [large intestine]), or kidney or liver disease.

  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking cephalexin, call your doctor.

Unless your doctor tells you otherwise, continue your normal diet.

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

  • Cephalexin may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

    • nausea

    • diarrhea

    • vomiting

    • heartburn

    • stomach pain

    • rectal or genital itching

    • dizziness

    • extreme tiredness

    • agitation

    • confusion

    • headache

    • joint pain

  • Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately or get emergency medical treatment:

    • watery or bloody stools, stomach cramps, or fever during treatment or for up to two or more months after stopping treatment

    • rash

    • itching

    • hives

    • swelling of the face, throat, tongue, lips, and eyes

    • difficulty breathing or swallowing

    • wheezing

    • a return of fever, sore throat, chills, or other signs of infection

    • hallucinations (seeing things or hearing voices that do not exist)

  • If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store the capsules and tablets at room temperature and away from excess heat and moisture (not in the bathroom). Keep liquid medicine in the refrigerator, tightly closed, and dispose of any unused medication after 14 days. .

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include:

  • nausea

  • vomiting

  • diarrhea

  • pink, red, or dark brown urine

  • stomach pain

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your response to cephalexin.

Before having any laboratory test, tell your doctor and the laboratory personnel that you are taking cephalexin.

If you are diabetic and test your urine for sugar, use Clinistix or TesTape (not Clinitest) to test your urine while taking this medication.

Do not let anyone else take your medication. Your prescription is probably not refillable.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Drug Interaction
Triamcinolone Triamcinolone The metabolism of Cephalexin can be increased when combined with Triamcinolone.
Pamidronate Injection Pamidronate Injection The risk or severity of nephrotoxicity and hypocalcemia can be increased when Cephalexin is combined with Pamidronic acid.
Vancomycin Injection Vancomycin Injection Cephalexin may decrease the excretion rate of Vancomycin which could result in a higher serum level.
Zidovudine Injection Zidovudine Injection The excretion of Cephalexin can be decreased when combined with Zidovudine.
Tenofovir Tenofovir Cephalexin may increase the nephrotoxic activities of Tenofovir.
Tinidazole Tinidazole Cephalexin may decrease the excretion rate of Tinidazole which could result in a higher serum level.
Voriconazole Voriconazole The metabolism of Cephalexin can be decreased when combined with Voriconazole.
Ibandronate Ibandronate The risk or severity of nephrotoxicity and hypocalcemia can be increased when Cephalexin is combined with Ibandronate.
Azacitidine Injection Azacitidine Injection Cephalexin may decrease the excretion rate of Azacitidine which could result in a higher serum level.
Doripenem Injection Doripenem Injection Cephalexin may decrease the excretion rate of Doripenem which could result in a higher serum level.
Ceftaroline Injection Ceftaroline Injection Ceftaroline fosamil may decrease the excretion rate of Cephalexin which could result in a higher serum level.
Ipilimumab Injection Ipilimumab Injection Cephalexin may decrease the excretion rate of Ipilimumab which could result in a higher serum level.
Terbutaline Injection Terbutaline Injection Cephalexin may decrease the excretion rate of Terbutaline which could result in a higher serum level.
Roflumilast Roflumilast Cephalexin may decrease the excretion rate of Roflumilast which could result in a higher serum level.
Linagliptin Linagliptin The metabolism of Cephalexin can be decreased when combined with Linagliptin.
Rilpivirine Rilpivirine The metabolism of Cephalexin can be decreased when combined with Rilpivirine.
Rivaroxaban Rivaroxaban Cephalexin may decrease the excretion rate of Rivaroxaban which could result in a higher serum level.
Ticagrelor Ticagrelor The metabolism of Cephalexin can be decreased when combined with Ticagrelor.
Brentuximab Vedotin Injection Brentuximab Vedotin Injection The metabolism of Cephalexin can be decreased when combined with Brentuximab vedotin.
Ruxolitinib Ruxolitinib The metabolism of Ruxolitinib can be decreased when combined with Cephalexin.
Vandetanib Vandetanib The metabolism of Vandetanib can be decreased when combined with Cephalexin.
Vemurafenib Vemurafenib The metabolism of Cephalexin can be decreased when combined with Vemurafenib.
Ivacaftor Ivacaftor The metabolism of Ivacaftor can be decreased when combined with Cephalexin.
Deferiprone Deferiprone Cephalexin may decrease the excretion rate of Deferiprone which could result in a higher serum level.
Axitinib Axitinib The metabolism of Axitinib can be decreased when combined with Cephalexin.
Crizotinib Crizotinib The metabolism of Cephalexin can be decreased when combined with Crizotinib.
Testosterone Injection Testosterone Injection Cephalexin may decrease the excretion rate of Testosterone which could result in a higher serum level.
Ziprasidone Injection Ziprasidone Injection The metabolism of Cephalexin can be decreased when combined with Ziprasidone.
Progestin-Only (drospirenone) Oral Contraceptives Progestin-Only (drospirenone) Oral Contraceptives The metabolism of Drospirenone can be decreased when combined with Cephalexin.
Viloxazine Viloxazine Cephalexin may decrease the excretion rate of Viloxazine which could result in a higher serum level.
Tobramycin Injection Tobramycin Injection Tobramycin may decrease the excretion rate of Cephalexin which could result in a higher serum level.
Theophylline Theophylline The metabolism of Theophylline can be decreased when combined with Cephalexin.
Tolmetin Tolmetin Tolmetin may decrease the excretion rate of Cephalexin which could result in a higher serum level.
Sulindac Sulindac Sulindac may decrease the excretion rate of Cephalexin which could result in a higher serum level.
Sucralfate Sucralfate Cephalexin may decrease the excretion rate of Sucralfate which could result in a higher serum level.
Tranylcypromine Tranylcypromine The metabolism of Cephalexin can be decreased when combined with Tranylcypromine.
Tetracycline Tetracycline Cephalexin may decrease the excretion rate of Tetracycline which could result in a higher serum level.
Sulfadiazine Sulfadiazine Cephalexin may decrease the excretion rate of Sulfadiazine which could result in a higher serum level.
Azathioprine Azathioprine Cephalexin may decrease the excretion rate of Azathioprine which could result in a higher serum level.
Warfarin Warfarin Cephalexin may decrease the excretion rate of Warfarin which could result in a higher serum level.
Triamterene Triamterene The risk or severity of nephrotoxicity can be increased when Triamterene is combined with Cephalexin.
Sulfinpyrazone Sulfinpyrazone The metabolism of Cephalexin can be increased when combined with Sulfinpyrazone.
Valproic Acid Valproic Acid The excretion of Valproic acid can be decreased when combined with Cephalexin.
Tamoxifen Tamoxifen The metabolism of Cephalexin can be decreased when combined with Tamoxifen.
Liothyronine Liothyronine Cephalexin may decrease the excretion rate of Liothyronine which could result in a higher serum level.
Tolbutamide Tolbutamide Cephalexin may decrease the excretion rate of Tolbutamide which could result in a higher serum level.
Tolazamide Tolazamide Cephalexin may decrease the excretion rate of Tolazamide which could result in a higher serum level.
Baclofen Baclofen Cephalexin may decrease the excretion rate of Baclofen which could result in a higher serum level.
Mercaptopurine Mercaptopurine The excretion of Mercaptopurine can be decreased when combined with Cephalexin.
Thiotepa Injection Thiotepa Injection The metabolism of Thiotepa can be decreased when combined with Cephalexin.
Vincristine Injection Vincristine Injection The metabolism of Vincristine can be decreased when combined with Cephalexin.
Vinblastine Vinblastine The metabolism of Cephalexin can be decreased when combined with Vinblastine.
Aspirin Aspirin Cephalexin may decrease the excretion rate of Acetylsalicylic acid which could result in a higher serum level.
Temazepam Temazepam Cephalexin may decrease the excretion rate of Temazepam which could result in a higher serum level.
Triazolam Triazolam Cephalexin may decrease the excretion rate of Triazolam which could result in a higher serum level.
Trimethoprim Trimethoprim Cephalexin may decrease the excretion rate of Trimethoprim which could result in a higher serum level.
Timolol Timolol Cephalexin may decrease the excretion rate of Timolol which could result in a higher serum level.
Verapamil Verapamil Cephalexin may decrease the excretion rate of Verapamil which could result in a higher serum level.
Auranofin Auranofin Cephalexin may decrease the excretion rate of Auranofin which could result in a higher serum level.
Aztreonam Injection Aztreonam Injection Cephalexin may decrease the excretion rate of Aztreonam which could result in a higher serum level.
Teniposide Injection Teniposide Injection The metabolism of Cephalexin can be decreased when combined with Teniposide.
Tramadol Tramadol Cephalexin may decrease the excretion rate of Tramadol which could result in a higher serum level.
Ticlopidine Ticlopidine Cephalexin may decrease the excretion rate of Ticlopidine which could result in a higher serum level.
Gemcitabine Injection Gemcitabine Injection Cephalexin may decrease the excretion rate of Gemcitabine which could result in a higher serum level.
Zafirlukast Zafirlukast The metabolism of Cephalexin can be decreased when combined with Zafirlukast.
Tolterodine Tolterodine Cephalexin may decrease the excretion rate of Tolterodine which could result in a higher serum level.
Rabeprazole Rabeprazole Cephalexin may decrease the excretion rate of Rabeprazole which could result in a higher serum level.

Content provided by: AHFS® Patient Medication Information™. © Copyright, 2021. The American Society of Health-System Pharmacists