Note: This document contains side effect information about cephalexin. Some dosage forms listed on this page may not apply to the brand name Keflex.

Applies to cephalexin: oral capsules, oral for suspension.

Side effects include:

Adverse GI effects, including diarrhea, nausea, vomiting, dyspepsia, gastritis, abdominal pain.

For Healthcare Professionals

Applies to cephalexin: oral capsule, oral powder for reconstitution, oral tablet, oral tablet dispersible.

General

The most commonly reported side effects included diarrhea, dyspepsia, gastritis, nausea, and vomiting.^[Ref]

Gastrointestinal

Frequency not reported: Diarrhea, nausea, vomiting, dyspepsia, gastritis, abdominal pain, anal pruritus, Clostridium difficile-associated diarrhea/colitis/pseudomembranous colitis

Postmarketing reports: Colitis^[Ref]

Hematologic

Frequency not reported: Direct Coombs' test seroconversion, decreased prothrombin activity/prolonged prothrombin time, eosinophilia, neutropenia, thrombocytopenia, hemolytic anemia

Postmarketing reports: Aplastic anemia, pancytopenia, leukopenia, agranulocytosis^[Ref]

Dermatologic

Frequency not reported: Urticaria, rash, erythema multiforme, Stevens Johnson syndrome, toxic epidermal necrolysis/exanthematic necrolysis^[Ref]

Hepatic

Frequency not reported: Transient hepatitis, cholestatic jaundice, AST and ALT elevations

Postmarketing reports: Increased bilirubin^[Ref]

Hypersensitivity

Frequency not reported: Hypersensitivity/allergic reactions, angioedema, anaphylaxis^[Ref]

Allergic reactions (including urticaria and angioedema) usually subsided upon treatment discontinuation.^[Ref]

Genitourinary

Frequency not reported: Genital pruritus, genital candidiasis, vulvovaginitis/vaginitis and vaginal discharge^[Ref]

Nervous system

Frequency not reported: Seizure, dizziness, headache^[Ref]

Psychiatric

Frequency not reported: Agitation, confusion, hallucinations^[Ref]

Musculoskeletal

Frequency not reported: Arthralgia, arthritis, joint disorder^[Ref]

Renal

Frequency not reported: Reversible interstitial nephritis

Postmarketing reports: Renal dysfunction, toxic nephropathy, increased blood urea nitrogen, increased creatinine^[Ref]

Other

Frequency not reported: Fatigue

Postmarketing reports: Fever^[Ref]

Immunologic

Frequency not reported: Development of drug-resistant bacteria development^[Ref]

Metabolic

Postmarketing reports: Increased alkaline phosphatase, increased lactate dehydrogenase (LDH)^[Ref]

Cardiovascular

Postmarketing reports: Hemorrhage^[Ref]