Cephalexin
Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
A first-generation cephalosporin antibiotic with excellent activity against gram-positive cocci including methicillin-susceptible S. aureus (MSSA) and streptococci. Commonly used for skin and soft tissue infections, uncomplicated urinary tract infections, bone and joint infections, and as prophylaxis for certain dental and surgical procedures. It has limited gram-negative coverage compared to later-generation cephalosporins.
Exploratory record, not a reviewed medical publication.
See the editorial and medical-review policies for the publication gate.
This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.
What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
A first-generation cephalosporin antibiotic with excellent activity against gram-positive cocci including methicillin-susceptible S. NutriStack rates the supporting evidence as strong. Common adult dosing is 250-500 mg every 6 hours or 500 mg-1 g every 12 hours; up to 4 g/day for severe infections (as prescribed by your physician), though a prescriber sets the actual dose. With long-term use it can deplete vitamin k. This profile indexes 10 sources.
- Diarrhea
- Nausea
- Abdominal pain
- Known cephalosporin allergy
- History of anaphylaxis to penicillins (use with caution; cross-reactivity ~1-2%)
The bottom line
Evidence rating strong. Most-documented uses: treats skin and soft tissue infections (cellulitis, impetigo), treats uncomplicated urinary tract infections, treats bone and joint infections. 10 sources indexed (2016–2025), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
Binds to penicillin-binding proteins (PBPs) in the bacterial cell wall, inhibiting the transpeptidation step of peptidoglycan synthesis. This disrupts cell wall integrity, leading to osmotic instability and bacterial cell lysis. As a first-generation cephalosporin, it is resistant to some but not all beta-lactamases.
Dosing & protocol.
Well absorbed orally with approximately 90% bioavailability. Food may delay absorption slightly but does not reduce total absorption. Can be taken with or without food.3
What it depletes.
Nutrients this medication can lower over time, and what to replace.
Vitamin K
MildBroad-spectrum antibiotic exposure can suppress gut bacteria that synthesize menaquinones, lowering vitamin K availability in susceptible patients.
Full safety detail.
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Meta-analyses & systematic reviews
1- 1A Systematic Review on the Clinical Pharmacokinetics of Cephalexin in Healthy and Diseased PopulationsPMIDKanan M, Atif S, Mohammed F et al. · Antibiotics (Basel, Switzerland) · 2023
Kanan M, Atif S, Mohammed F et al.. A Systematic Review on the Clinical Pharmacokinetics of Cephalexin in Healthy and Diseased Populations. Antibiotics (Basel, Switzerland). 2023
Randomized controlled trials
2- 2Prophylactic Oral Cephalexin and Metronidazole Compared With Placebo After Cesarean Delivery to Reduce Infection Complications in Women With Obesity: A Randomized Controlled TrialPMIDSaad AF, Goldman B, Spencer N et al. · Obstetrics and gynecology · 2025
Saad AF, Goldman B, Spencer N et al.. Prophylactic Oral Cephalexin and Metronidazole Compared With Placebo After Cesarean Delivery to Reduce Infection Complications in Women With Obesity: A Randomized Controlled Trial. Obstetrics and gynecology. 2025
- 3High-dose cephalexin for cellulitis: a pilot randomized controlled trialPMIDYadav K, Eagles D, Perry JJ et al. · CJEM · 2023
Yadav K, Eagles D, Perry JJ et al.. High-dose cephalexin for cellulitis: a pilot randomized controlled trial. CJEM. 2023
Reviews & position papers
2- 4Hydrophilic-interaction planar chromatography in ultra-sensitive determination of α-aminocephalosporin antibiotics. Application to analysis of cefalexin in goat milk samples using modified QuEChERS extraction techniquePMIDRageh AH, Abdel-Rahim SA, Askal HF et al. · Journal of pharmaceutical and biomedical analysis · 2019
Rageh AH, Abdel-Rahim SA, Askal HF et al.. Hydrophilic-interaction planar chromatography in ultra-sensitive determination of α-aminocephalosporin antibiotics. Application to analysis of cefalexin in goat milk samples using modified QuEChERS extraction technique. Journal of pharmaceutical and biomedical analysis. 2019
- 5Temperature rise and microplastics interact with the toxicity of the antibiotic cefalexin to juveniles of the common goby (Pomatoschistus microps): Post-exposure predatory behaviour, acetylcholinesterase activity and lipid peroxidationPMIDFonte E, Ferreira P, Guilhermino L · Aquatic toxicology (Amsterdam, Netherlands) · 2016
Fonte E, Ferreira P, Guilhermino L. Temperature rise and microplastics interact with the toxicity of the antibiotic cefalexin to juveniles of the common goby (Pomatoschistus microps): Post-exposure predatory behaviour, acetylcholinesterase activity and lipid peroxidation. Aquatic toxicology (Amsterdam, Netherlands). 2016
Reference material
5- 6Stevens DL et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the IDSA. Clin Infect Dis. 2014.Source linkedPMID
- 7Gupta K et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: a 2010 update by IDSA and ESCMID. Clin Infect Dis. 2011.Source linkedPMID
- 8Shu Z et al. Efficacy and safety of first- and second-line antibiotics for cellulitis and erysipelas: a network meta-analysis of randomized controlled trials. Arch Dermatol Res. 2024.Source linkedPMID
- 9Valent AM, DeArmond C, Houston JM et al.. Effect of Post-Cesarean Delivery Oral Cephalexin and Metronidazole on Surgical Site Infection Among Obese Women: A Randomized Clinical Trial. JAMA. 2017Source linkedPMID
- 10Herman TF, Hashmi MF. Cephalexin. 2026Source linkedPMID
Common questions.
Quick answers about Cephalexin, drawn from the data on this page.
What is Cephalexin?
A first-generation cephalosporin antibiotic with excellent activity against gram-positive cocci including methicillin-susceptible S. aureus (MSSA) and streptococci. Commonly used for skin and soft tissue infections, uncomplicated urinary tract infections, bone and joint infections, and as prophylaxis for certain dental and surgical procedures. It has limited gram-negative coverage compared to later-generation cephalosporins.
What is Cephalexin used for?
Commonly cited benefits of Cephalexin include: Treats skin and soft tissue infections (cellulitis, impetigo); Treats uncomplicated urinary tract infections; Treats bone and joint infections; Treats streptococcal pharyngitis (penicillin alternative); Surgical prophylaxis. NutriStack rates the overall evidence as strong.
What is a typical dose of Cephalexin?
A typical adult dose of Cephalexin is 250-500 mg every 6 hours or 500 mg-1 g every 12 hours; up to 4 g/day for severe infections (as prescribed by your physician). The commonly recommended form is Oral capsules or suspension. These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of Cephalexin?
Reported side effects include diarrhea, nausea, abdominal pain, skin rash, vaginal candidiasis, headache. This is educational information; check with a healthcare professional before use.
How strong is the evidence for Cephalexin?
NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
Use this with your stack
Cephalexin in NutriStack.
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