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Quick facts
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 309114
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
Cephalexin capsules are a cephalosporin antibacterial drug indicated for the treatment of the following infections caused by susceptible isolates of designated bacteria: Respiratory tract infection ( 1.1 ) Otitis media ( 1.2 ) Skin and skin structure infections ( 1.3 ) Bone infections ( 1.4 ) Genitourinary tract infections ( 1.5 ) To reduce the development of drug-resistant bacteria and maintain the effectiveness of cephalexin capsules and other antibacterial drugs, cephalexin capsules should be used only to treat infections that are proven or strongly suspected to be caused by bacteria. ( 1.6 ) 1.1 Respiratory Tract Infections Cephalexin capsules are indicated for the treatment of respiratory tract infections caused by susceptible isolates of Streptococcus pneumoniae and Streptococcus pyogenes. 1.2 Otitis Media Cephalexin capsules are indicated for the treatment of otitis media caused by susceptible isolates of Streptococcus pneumoniae , Haemophilus influenzae , Staphylococcus aureus , Streptococcus pyogenes , and Moraxella catarrhalis. 1.3 Skin and Skin Structure Infections Cephalexin capsules are indicated for the treatment of skin and skin structure infections caused by susceptible isolates of the following Gram-positive bacteria: Staphylococcus aureus and Streptococcus pyogenes . 1.4 Bone Infections Cephalexin capsules are indicated for the treatment of bone infections caused by susceptible isolates of Staphylococcus aureus and Proteus mirabilis. 1.5 Genitourinary Tract Infections Cephalexin capsules are indicated for the treatment of genitourinary tract infections, including acute prostatitis, caused by susceptible isolates of Escherichia coli , Proteus mirabilis , and Klebsiella pneumoniae . 1.6 Usage To reduce the development of drug-resistant bacteria and maintain the effectiveness of cephalexin capsules and other antibacterial drugs, cephalexin capsules should be used only to treat infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information is available, this information should be considered in selecting or modifying antibacterial therapy. […]
About this medicine
Cephalexin capsules, USP is a semisynthetic cephalosporin antibacterial drug intended for oral administration. It is 7-(D-α-Amino-α-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid monohydrate. Cephalexin has the molecular formula C 16 H 17 N 3 O 4 S•H 2 O and the molecular weight is 365.41. Cephalexin has the following structural formula: Each capsule contains cephalexin monohydrate equivalent to 250 mg or 500 mg of cephalexin. The capsules also contain the following inactive ingredients: microcrystalline cellulose, croscarmellose sodium, D&C Yellow No. 10, FD&C Blue No. 1, FD&C Yellow No. 6, gelatin, magnesium stearate, titanium dioxide, and sodium lauryl sulfate. FDA approved dissolution test specifications differs from the USP. structure
How it works
12.1 Mechanism of Action Cephalexin is a cephalosporin antibacterial drug [see Microbiology (12.4) ] .
Who should not take it
Cephalexin capsules are contraindicated in patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. Patients with known hypersensitivity to cephalexin or other members of the cephalosporin class of antibacterial drugs. ( 4 )
Warnings and cautions
Serious hypersensitivity (anaphylactic) reactions : Prior to use, inquire regarding history of hypersensitivity to beta-lactam antibacterial drugs. Discontinue the drug if signs or symptoms of an allergic reaction occur and institute supportive measures. ( 5.1 ) Clostridium difficile -associated diarrhea (CDAD ): Evaluate if diarrhea occurs. ( 5.2 ) Direct Coombs’ Test Seroconversion : If anemia develops during or after cephalexin therapy, evaluate for drug-induced hemolytic anemia. ( 5.3 ) Seizure Potential : Use lower dose in patients with renal impairment. ( 5.4 ) 5.1 Hypersensitivity Reactions Allergic reactions in the form of rash, urticaria, angioedema, anaphylaxis, erythema multiforme, Stevens-Johnson syndrome, or toxic epidermal necrolysis have been reported with the use of cephalexin. Before therapy with cephalexin is instituted, inquire whether the patient has a history of hypersensitivity reactions to cephalexin, cephalosporins, penicillins, or other drugs. Cross-hypersensitivity among beta-lactam antibacterial drugs may occur in up to 10% of patients with a history of penicillin allergy. If an allergic reaction to cephalexin occurs, discontinue the drug and institute appropriate treatment. 5.2 Clostridium difficile -Associated Diarrhea Clostridium difficile - associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including cephalexin, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile . C. difficile produces toxins A and B, which contribute to the development of CDAD. Hypertoxin-producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. […]
Reported side effects
The following serious events are described in greater detail in the Warning and Precautions section: Hypersensitivity reactions [see Warning and Precautions (5.1) ] Clostridium difficile -associated diarrhea [see Warnings and Precautions (5.2) ] Direct Coombs’ Test Seroconversion [see Warnings and Precautions (5.3) ] Seizure Potential [see Warnings and Precautions (5.4) ] Effect on Prothrombin Activity [see Warnings and Precautions (5.5) ] Development of Drug-Resistant Bacteria [see Warnings and Precautions (5.6) ] The most common adverse reactions associated with cephalexin include diarrhea, nausea, vomiting, dyspepsia and abdominal pain . ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Aurobindo Pharma USA, Inc. at 1-866-850-2876 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In clinical trials, the most frequent adverse reaction was diarrhea. Nausea and vomiting, dyspepsia, gastritis, and abdominal pain have also occurred. As with penicillins and other cephalosporins, transient hepatitis and cholestatic jaundice have been reported. Other reactions have included hypersensitivity reactions, genital and anal pruritus, genital candidiasis, vaginitis and vaginal discharge, dizziness, fatigue, headache, agitation, confusion, hallucinations, arthralgia, arthritis, and joint disorder. Reversible interstitial nephritis has been reported. Eosinophilia, neutropenia, thrombocytopenia, hemolytic anemia, and slight elevations in aspartate transaminase (AST) and alanine transaminase (ALT) have been reported. In addition to the adverse reactions listed above that have been observed in patients treated with cephalexin, the following adverse reactions and other altered laboratory tests have been reported for cephalosporin class antibacterial drugs: Other Adverse Reactions : Fever, colitis, aplastic anemia, hemorrhage, renal dysfunction, and toxic nephropathy. […]
Interactions with other medicines
Metformin: increased metformin concentrations. Monitor for hypoglycemia. ( 7.1 ) Probenecid-The renal excretion of cephalexin is inhibited by probenecid. Co-administration of probenecid with cephalexin is not recommended. ( 7.2 ) Administration of cephalexin may result in a false-positive reaction glucose in the urine. ( 7.3 ) 7.1 Metformin Administration of cephalexin with metformin results in increased plasma metformin concentrations and decreased renal clearance of metformin. Careful patient monitoring and dose adjustment of metformin is recommended in patients concomitantly taking cephalexin and metformin [see Clinical Pharmacology (12.3) ]. 7.2 Probenecid The renal excretion of cephalexin is inhibited by probenecid. Co-administration of probenecid with cephalexin is not recommended. 7.3 Interaction with Laboratory or Diagnostic Testing A false-positive reaction may occur when testing for the presence of glucose in the urine using Benedict’s solution or Fehling’s solution.
Use in specific groups
Renal Impairment: Monitor patients longer for toxicity and drug interactions due to delayed clearance. (8.6) 8.1 Pregnancy Risk Summary Available data from published epidemiologic studies and pharmacovigilance case reports over several decades with cephalosporin use, including cephalexin use in pregnant women have not established drug-associated risks of major birth defects, miscarriage, or adverse maternal or fetal outcomes (see Data) . Animal reproduction studies with mice and rats using oral doses of cephalexin that are 0.6- and 1.2-times the maximum recommended human dose (MRHD) based on body surface area during organogenesis revealed no evidence of harm to the fetus (see Data). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Human Data While available studies cannot definitively establish the absence of risk, published data from epidemiologic studies and postmarketing case reports over several decades have not identified a consistent association with cephalosporin use, including cephalexin, during pregnancy, and major birth defects, miscarriage, or other adverse maternal or fetal outcomes. Available studies have methodologic limitations, including small sample size, retrospective data collection, and inconsistent comparator groups. Animal Data In animal reproduction studies, pregnant mice and rats administered oral cephalexin doses of 250 or 500 mg/kg/day (approximately 0.6 and 1.2 times the MRHD) based on body surface area, respectively during the period of organogenesis showed no adverse effects on embryofetal development. In a pre-and post-natal developmental toxicity study, pregnant rats that received oral doses of 250 or 500 mg/kg/day of cephalexin from Day 15 of pregnancy to litter Day 21 showed no adverse effects on parturition, litter size, or growth of offspring. […]
If too much is taken
Symptoms of oral overdose may include nausea, vomiting, epigastric distress, diarrhea, and hematuria. In the event of an overdose, institute general supportive measures. Forced diuresis, peritoneal dialysis, hemodialysis, or charcoal hemoperfusion have not been established as beneficial for an overdose of cephalexin.
Before you take anything new
Tell your pharmacist or doctor about every medicine you take — including ones bought without a prescription, herbal products and supplements. Interactions are one of the most common avoidable causes of harm from medicines, and a pharmacist can check your full list in a couple of minutes.
This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 11 February 2025. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.