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[Pharmacology](https://durgical.com/en/pharmacology/) · [Beta-lactams](https://durgical.com/en/pharmacology/classes/beta-lactams/)

# Dicloxacillin

An oral penicillinase-resistant penicillin for skin and soft-tissue infections due to methicillin-susceptible Staphylococcus aureus.

Updated 2026-11-01

- Class: [Beta-lactams](https://durgical.com/en/pharmacology/classes/beta-lactams/)
- Enzyme: Penicillin-binding proteins (bacterial transpeptidases)
- ATC code: J01CF01

✂**Penicillin-binding proteins (bacterial transpeptidases)**Dicloxacillin

ⓘ The figure shows oxacillin, an isoxazolyl penicillin of the same group, in Staphylococcus aureus PBP1; no structure of this drug bound to a PBP has been published.

**Target in 3D:** Penicillin-binding proteins (bacterial transpeptidases). PDB structure 8VBU (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/8VBU) · Drag to rotate · pinch to zoom

## Mechanism of action

Dicloxacillin is an oral isoxazolyl penicillin, stable in stomach acid. It belongs to the penicillins resistant to staphylococcal β-lactamase: its bulky side chain keeps penicillinase from opening the β-lactam ring, so it acylates the PBPs of penicillinase-producing staphylococci. It does not work against MRSA, whose PBP2a has low affinity for β-lactams.

- Staphylococcal penicillinase cannot open its ring
- Acylates the staphylococcal PBPs
- Peptidoglycan cross-linking stops
- The staphylococcus lyses

## Pharmacokinetics

**Absorption**
Oral; better absorbed on an empty stomach.

**Distribution**
Very high protein binding, mainly to albumin; reaches bile and pleural and amniotic fluids.

**Elimination**
By the kidney and by liver inactivation and bile.

**Half-life**
Short, under one hour.

## Indications

- Skin and soft-tissue infections due to penicillinase-producing staphylococci. [Cellulitis of the leg →](https://durgical.com/en/conditions/cellulitis-of-the-leg/)
- Staphylococcal osteomyelitis and septic arthritis. [Osteomyelitis →](https://durgical.com/en/conditions/osteomyelitis/)

## Adverse effects

### Common

- Nausea, vomiting, diarrhoea, epigastric pain
- Rash

### Serious (rare, important)

- Anaphylaxis
- Clostridioides difficile diarrhoea, from mild to severe colitis
- Interstitial nephritis and blood disorders (rare)

## Contraindications

- History of a hypersensitivity reaction to any penicillin

## Key interactions

**Warfarin and other coumarins**
May reduce the anticoagulant effect; the INR is monitored.

**Tetracyclines**
Bacteriostatic: they can antagonise the bactericidal effect; the combination is avoided.

## What is monitored

- INR if the patient takes warfarin
- Kidney and liver function and blood count in long courses

## Administration and safety

- Oral, one hour before or two hours after meals.
- Do not confuse dicloxacillin with doxycycline or cloxacillin.

## Nursing care

- Before the first dose: ask about allergy to penicillins, cephalosporins and other β-lactams, and what the reaction was.
- Explain that it is taken away from meals.
- Check whether the patient takes warfarin.
- Teach the patient to report watery or bloody diarrhoea, even weeks after the course ends.

## Pregnancy and breastfeeding

Animal studies showed no fetal harm and there are no controlled studies in pregnant women; used if clearly needed.

## Memory aid

'Di-cloxacillin = two chlorines, double helmet': the oral isoxazolyl against susceptible staphylococci; the stomach must be empty to let it in.

## Test yourself

Think of the answer, then tap the question to see it.

## Against which staphylococci does dicloxacillin work, and against which not?

It works against methicillin-susceptible penicillinase producers; not against MRSA, which carries PBP2a.

## Which anticoagulant interaction does its label describe?

It may reduce the response to warfarin; the INR is monitored.

## When is dicloxacillin given relative to meals?

Away from them: one hour before or two hours after, because it is better absorbed fasting.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/dicloxacillin/)

## Related drugs

- [Cloxacillin](https://durgical.com/en/pharmacology/cloxacillin/)
- [Flucloxacillin](https://durgical.com/en/pharmacology/flucloxacillin/)
- [Oxacillin](https://durgical.com/en/pharmacology/oxacillin/)
- [Cefalexin](https://durgical.com/en/pharmacology/cefalexin/)

## Related conditions

- [Cellulitis of the leg](https://durgical.com/en/conditions/cellulitis-of-the-leg/)
- [Osteomyelitis](https://durgical.com/en/conditions/osteomyelitis/)

[← Back to the class: Beta-lactams](https://durgical.com/en/pharmacology/classes/beta-lactams/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Dicloxacillin: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a685017.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [DailyMed - DICLOXACILLIN SODIUM capsule](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=58e6ee7a-8237-ec66-e063-6394a90a5cae) (DailyMed (U.S. National Library of Medicine), 2026); [RCSB PDB - 8VBU: Structure of the monofunctional Staphylococcus aureus PBP1 in its beta-lactam (Oxacillin) inhibited form](https://www.rcsb.org/structure/8VBU) (RCSB Protein Data Bank, 2026); Farmacología básica y clínica (Katzung), cap. 43 (McGraw Hill, 2025).

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Representative model, for educational purposes only.

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