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Cloxacillin

Medication penicillinase-resistant penicillin antibiotic
Aka: Orbenin
Brands seen in Singapore: Cloxacap, Oxacil, Cloxacillin Panpharma, Meixam
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Prescribed for staph and other bacterial infections
When to take
Every six hours · half to one hour before food (SG)
Take with
Water, on an empty stomach · 2 h apart from probiotics
Pros & cons
Pros
  • Holds up against penicillinase-producing staph
  • Capsules and granules both registered in SG
  • Oral form used as follow-up after injections
Cons
  • Penicillin allergy can be serious — labels warn
  • Diarrhoea, nausea and bloating are common (SG)
  • Not for initial treatment of severe infections
Sources
  1. HSA — Listing of Registered Therapeutic Products (data.gov.sg open dataset; filtered locally for cloxacillin) · read 2026-08-27
    what it says
    “Forensicclassification = 'Prescription Only' for all 5 cloxacillin rows: SIN05036P CLOXACAP 250 CAPSULE; SIN08889P CLOXACAP 500 CAPSULE; SIN09934P OXACIL GRANULES 125MG/5ML; SIN07168P CLOXACILLIN PANPHARMA FOR INJECTION; SIN15834P MEIXAM POWDER FOR SOLUTION FOR INJECTION”
  2. MOH National Drug Formulary — CLOXACAP 500 CAPSULE 500 MG [SIN08889P], product information · read 2026-08-27
    what it says
    “CLOXACILLIN SODIUM EQV CLOXACILLIN - 500 MG … Dosage Form CAPSULE … Forensic Classification PRESCRIPTION ONLY MEDICINES … Prescription-only Medicines with Exemptions for Supply without Prescription NA”
  3. MOH National Drug Formulary — CLOXACAP 500 [SIN08889P], indications · read 2026-08-27
    what it says
    “For treatment of: Infections caused by penicillinase-producing staphylococci … Respiratory tract infections … Skin and soft-tissue infections … Disseminated infections caused by pneumococci, group A beta-hemolytic streptococci”
  4. MOH National Drug Formulary — CLOXACAP 500 [SIN08889P], dosage and administration · read 2026-08-27
    what it says
    “Adult dose Oral, 250 to 500 mg every six hours; or as directed. Paediatric dose … Oral 12.5 to 25 mg per kg of body weight every six hours; or as directed.”
  5. MOH National Drug Formulary — CLOXACAP 500 [SIN08889P], dosage note · read 2026-08-27
    what it says
    “Cloxacillin should not be used orally for the initial treatment of severe life-threatening infections, but may be used as a follow-up therapy after parenteral penicillinase-resistant penicillin therapy.”
  6. MOH National Drug Formulary — CLOXACAP 500 [SIN08889P], contraindications · read 2026-08-27
    what it says
    “Avoid in patients known to be hypersensitive to penicillins.”
  7. HealthHub (National Medication Information workgroup / Pharmaceutical Society of Singapore) — Cloxacillin medication information leaflet · read 2026-08-27
    what it says
    “Cloxacillin belongs to a group of antibiotics known as penicillin, and is used to treat bacterial infections. It works by stopping the growth of bacteria.”
  8. HealthHub — Cloxacillin: how should I take or use this medication · read 2026-08-27
    what it says
    “Take this medication half to one hour before food. You should complete each course of antibiotics even if you feel better as incomplete treatment might cause the infection to return or cause antibiotic resistance.”
  9. HealthHub — Cloxacillin: what precautions should I take · read 2026-08-27
    what it says
    “Inform your healthcare professional if: You had a previous allergic reaction to Cloxacillin, Amoxicillin, Penicillins, Cephalexin, Cefuroxime or other beta lactam antibiotics … You have kidney problems.”
  10. HealthHub — Cloxacillin: common side effects · read 2026-08-27
    what it says
    “Some common side effects include: Diarrhoea Nausea, vomiting Stomach upset or discomfort Bloating … you may develop a black, "hairy" tongue while taking this medication. This effect is harmless”
  11. HealthHub — Cloxacillin: rare but serious side effects · read 2026-08-27
    what it says
    “Persistent diarrhoea, abdominal or stomach pain/cramp, blood/mucus in your stool This could suggest a severe intestinal condition (pseudomembranous colitis). This condition may occur during the course of this medication or weeks after”
  12. HealthHub — Cloxacillin: what food or medication should I avoid · read 2026-08-27
    what it says
    “Take this medication 2 hours apart from probiotics as the antibiotics may reduce the effectiveness of probiotics.”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.