Cephalexin interactions

Cephalexin (Keflex), a cephalosporin has 85 documented interactions across the FDA labels and fact sheets we index: 25 major, 30 moderate, 30 minor, and 0 where a label reports no significant interaction. Each entry below quotes the sentence behind it. This drug page is a starting point, not a verdict for your situation.

What Cephalexin looks like

All 29 versions
Cephalexin 150 mg tablet: white, oval, 13 mm, scored, no imprint.
No imprint
150 mg · white · oval · 13 mm · scored
Virbac AH
Cephalexin 300 mg tablet: white, oval, 17 mm, scored, no imprint.
No imprint
300 mg · white · oval · 17 mm · scored
Virbac AH
Cephalexin 600 mg tablet: white, oval, 22 mm, scored, no imprint.
No imprint
600 mg · white · oval · 22 mm · scored
Virbac AH
Cephalexin 500 mg capsule: green, 21 mm, imprinted A 43 500 mg.
A / 43 / 500 / mg
500 mg · green · capsule · 21 mm
Amella

Renderings from the FDA labels' product listings: color, shape, size, and imprint. 29 documented versions from 18 labelers.

Interactions from the label

Major interactions (25)

  • Amoxicillinpenicillin antibioticMajor

    AMOXIL is contraindicated in patients who have experienced a serious hypersensitivity reaction (e.g., anaphylaxis or Stevens-Johnson syndrome) to AMOXIL or to other β-lactam antibacterial drugs (e.g., penicillins and cephalosporins). (Amoxicillin label, Contraindications)

  • Amoxicillin and clavulanatepenicillin antibioticMajor

    History of a serious hypersensitivity reaction (e.g., anaphylaxis or Stevens-Johnson syndrome) to AUGMENTIN or to other beta‑lactams (e.g., penicillins or cephalosporins). (Amoxicillin and clavulanate label, Contraindications)

  • Ampicillinpenicillin antibioticMajor

    CONTRAINDICATIONS The use of Ampicillin is contraindicated in individuals with a history of serious hypersensitivity reactions (e.g., anaphylaxis or Stevens-Johnson syndrome) to ampicillin or to other beta-lactam antibacterial drugs. (Ampicillin label, Contraindications)

  • Ampicillin and sulbactampenicillin antibioticMajor

    CONTRAINDICATIONS The use of UNASYN is contraindicated in individuals with a history of serious hypersensitivity reactions (e.g., anaphylaxis or Stevens-Johnson syndrome) to ampicillin, sulbactam or to other beta-lactam antibacterial drugs (e.g., penicillins and cephalosporins). (Ampicillin and sulbactam label, Contraindications)

  • CefaclorcephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefadroxilcephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefazolincephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefdinircephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefepimecephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefiximecephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefotaximecephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefotetancephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefoxitincephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefpodoximecephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefprozilcephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CeftarolinecephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CeftazidimecephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CeftriaxonecephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • CefuroximecephalosporinMajor

    Cephalexin is contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. (Cephalexin label, Contraindications)

  • ErtapenemantibioticMajor

    INVANZ is contraindicated in patients with known hypersensitivity to any component of this product or to other drugs in the same class or in patients who have demonstrated anaphylactic reactions to beta-lactams. (Ertapenem label, Contraindications)

  • Hypersensitivity Reactions: Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving therapy with beta-lactams. (Imipenem and cilastatin label, Warnings and precautions)

  • Nafcillinpenicillin antibioticMajor

    WARNINGS Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving beta-lactam antibacterial drugs. (Nafcillin label, Warnings)

  • Piperacillin and tazobactampenicillin antibioticMajor

    Piperacillin and Tazobactam for Injection and Sodium Chloride Injection is contraindicated in patients with a history of allergic reactions to any of the penicillins, cephalosporins, or betalactamase inhibitors. (Piperacillin and tazobactam label, Contraindications)

  • Co-administration of probenecid with cephalexin for oral suspension is not recommended. (Cephalexin label, Drug interactions)

  • Co-administration of probenecid with cephalexin for oral suspension is not recommended. (Cephalexin label, Drug interactions)

Moderate interactions (30)

  • Alogliptin and metforminDPP-4 inhibitorModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • ApixabananticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • ArgatrobananticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • AztreonamantibioticModerate

    Use caution when CAYSTON is administered to patients with a known allergic reaction to beta-lactams. (Aztreonam label, Warnings and precautions)

  • BivalirudinanticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • DabigatrananticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • Dapagliflozin and metforminSGLT2 inhibitorModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • Dicloxacillinpenicillin antibioticModerate

    • Serious hypersensitivity (anaphylactic) reactions: Prior to use, inquire regarding history of hypersensitivity to beta-lactam antibacterial drugs. (Cephalexin label, Warnings and precautions)

  • EdoxabananticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • Empagliflozin and metforminSGLT2 inhibitorModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • EnoxaparinanticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • Ethacrynic acidloop diureticModerate

    Ethacrynic acid may increase the ototoxic potential of other drugs such as aminoglycoside and some cephalosporin antibiotics. (Ethacrynic acid label, Drug interactions)

  • FondaparinuxanticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • Furosemideloop diureticModerate

    Cephalosporin Furosemide can increase the risk of cephalosporin-induced nephrotoxicity even in the setting of minor or transient renal impairment. (Furosemide label, Drug interactions)

  • GentamicinaminoglycosideModerate

    Increased nephrotoxicity has been reported following concomitant administration of aminoglycoside antibiotics and cephalosporins. (Gentamicin label, Drug interactions)

  • Glipizide and metforminsulfonylureaModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • Glyburide and metforminsulfonylureaModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • HeparinanticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • Linagliptin and metforminDPP-4 inhibitorModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • MetforminbiguanideModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • MycophenolateimmunosuppressantModerate

    Examples Cyclosporine A, trimethoprim/sulfamethoxazole, bile acid sequestrants (cholestyramine), rifampin as well as aminoglycoside, cephalosporin, fluoroquinolone and penicillin classes of antimicrobials Drugs Modulating Glucuronidation Clinical Impact Concomitant use with drugs inducing glucuronidation decreases MPA systemic exposure, potentially reducing mycophenolate… (Mycophenolate label, Drug interactions)

  • Oxacillinpenicillin antibioticModerate

    • Serious hypersensitivity (anaphylactic) reactions: Prior to use, inquire regarding history of hypersensitivity to beta-lactam antibacterial drugs. (Cephalexin label, Warnings and precautions)

  • Penicillin Gpenicillin antibioticModerate

    • Serious hypersensitivity (anaphylactic) reactions: Prior to use, inquire regarding history of hypersensitivity to beta-lactam antibacterial drugs. (Cephalexin label, Warnings and precautions)

  • Penicillin Vpenicillin antibioticModerate

    • Serious hypersensitivity (anaphylactic) reactions: Prior to use, inquire regarding history of hypersensitivity to beta-lactam antibacterial drugs. (Cephalexin label, Warnings and precautions)

  • Pioglitazone and metforminthiazolidinedioneModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • ProtamineModerate

    Drug Interactions Protamine sulfate has been shown to be incompatible with certain antibiotics, including several of the cephalosporins and penicillins (see DOSAGE AND ADMINISTRATION ). (Protamine label, Precautions)

  • RivaroxabananticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

  • Saxagliptin and metforminDPP-4 inhibitorModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • Sitagliptin and metforminDPP-4 inhibitorModerate

    • Metformin: increased metformin concentrations. (Cephalexin label, Drug interactions)

  • WarfarinanticoagulantModerate

    Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. (Cephalexin label, Warnings and precautions)

Minor mentions (30)

  • BrivaracetamanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • Cannabidiol (prescription)anticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • CarbamazepineanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • CenobamateanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • ClobazambenzodiazepineMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • ClonazepambenzodiazepineMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • Divalproex (valproate)anticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • EslicarbazepineanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • EthosuximideanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • FelbamateanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • FosphenytoinanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • GabapentinanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • LacosamideanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • LamotrigineanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • LevetiracetamanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • MeropenemantibioticMinor

    Before initiating therapy with Meropenem for injection, it is important to inquire about previous hypersensitivity reactions to penicillins, cephalosporins, other β-lactams, and other allergens. (Meropenem label, Warnings and precautions)

  • MethsuximideanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • OxcarbazepineanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • PerampanelanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • PhenobarbitalbarbiturateMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • Phentermine and topiramateCNS stimulantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • PhenytoinanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • PregabalinanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • PrimidoneanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • RufinamideanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • TiagabineanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • TopiramateanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • Valproic acidanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • VigabatrinanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

  • ZonisamideanticonvulsantMinor

    Anticonvulsant therapy can be given if clinically indicated. (Cephalexin label, Warnings and precautions)

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Not medical advice. Severity reflects the label's wording, not your circumstances. A "major" flag can be routine under supervision and a "minor" one can matter at high doses. Ask a pharmacist.