Keflex is a brand-name medication that contains cephalexin as its active ingredient. Cephalexin belongs to the β-lactam antibiotic class known as first-generation cephalosporins. In Hong Kong, Keflex is available by prescription only and is supplied as oral pill tablets in strengths of 250 mg and 500 mg. The drug is manufactured by several pharmaceutical companies and is regulated by the Hong Kong Department of Health.
Cephalexin interferes with bacterial cell-wall synthesis. It binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, blocking the cross-linking of peptidoglycan strands. Without a functional wall, bacteria cannot maintain their shape and burst under osmotic pressure. This mechanism makes Keflex bactericidal and effective against many Gram-positive organisms (such as Staphylococcus aureus and Streptococcus species) and some Gram-negative bacteria (including Escherichia coli and Klebsiella species). After oral ingestion, the tablets are rapidly absorbed; peak plasma concentrations typically appear within 1 hour and the drug’s half-life is about 1 hour, allowing a six-hour dosing interval for most infections.
Keflex is approved in Hong Kong for the treatment of a range of bacterial infections, including:
These indications reflect the infections for which clinical trials have demonstrated efficacy and for which local regulatory authorities have granted approval.
When in doubt, clinicians should review the patient’s medication history, allergies, and organ function before prescribing.
These effects are usually transient; staying hydrated and taking the tablet with food can reduce discomfort.
Patients should disclose all prescription medicines, over-the-counter drugs, herbal supplements, and dietary habits to their healthcare provider before initiating therapy.
Standard dosing for most adult infections:
250 mg tablet taken every 6 hours (four times daily), or
500 mg tablet taken every 6 hours for moderate-to-severe infections.
Maximum daily dose should not exceed 4 g (8 tablets of 500 mg).
Renal adjustment (example):
CrCl 20-30 mL/min - 250 mg every 12 hours.
Administration tips: swallow tablets whole with a full glass of water; do not crush or chew unless advised by a pharmacist.
Missed dose: take the missed tablet as soon as remembered unless it is within ½ dose interval of the next scheduled dose-do not double-dose.
Overdose: symptoms may include nausea, vomiting, diarrhea, and abdominal pain. Seek emergency medical attention; supportive care is the mainstay of treatment.
Discontinuation: complete the full prescribed course even if symptoms improve, to prevent resistance and relapse. Abrupt stop is generally safe for short courses but discuss with a clinician for prolonged therapy.
Dosing must always be individualized; the above regimens are typical examples based on the available 250 mg and 500 mg tablets.
This article provides educational information about Keflex and is not a substitute for professional medical advice. Treatment decisions, including use for unapproved indications, must be made under the guidance of a qualified healthcare provider. The content is intended for informational purposes and does not constitute medical recommendations. Always consult a physician before starting, stopping, or changing any medication regimen.
Yes. Cephalexin’s absorption is not significantly affected by food, so it may be taken with or without meals. Taking it with food can help reduce stomach upset.
Patients often notice improvement in symptoms within 2-3 days, although the full antimicrobial effect continues throughout the prescribed course.
Keflex is classified as Category B, indicating that animal studies have not shown risk and there are no well-controlled human studies. It may be prescribed when the expected benefit outweighs potential risks.
Cephalexin may reduce the efficacy of oral contraceptives by altering gut flora. Using a backup non-hormonal method (e.g., condoms) during treatment is advisable.
Mild rashes are common and may resolve on their own, but any sign of a severe skin reaction (blistering, swelling, fever) requires immediate medical attention.
Yes, but keep the medication in its original labeled packaging, carry a copy of the prescription, and be aware of any import restrictions of the destination country.
Elderly individuals often have reduced renal function; clinicians may lower the dose or extend the dosing interval based on kidney function tests.
Store the tablets in a tightly sealed container away from moisture. If humidity is high, keep the bottle in a cool, dry place such as a cabinet rather than a bathroom.
Incomplete courses or inappropriate use can promote resistant bacterial strains. Completing the full prescribed regimen reduces this risk.
Probiotics may help maintain normal gut flora during antibiotic therapy and are generally safe to use alongside Keflex; however, take them several hours apart to avoid potential interference.
