Dicloxacillin

Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

Dicloxacillin is a narrow-spectrum, penicillinase-resistant penicillin used primarily for infections caused by beta-lactamase-producing (penicillinase-producing) Staphylococcus aureus, such as skin and soft-tissue infections. It is acid-stable and given orally, making it a common oral step-down or outpatient option for methicillin-susceptible staphylococcal disease. It has no useful activity against methicillin-resistant S. aureus (MRSA) or most gram-negative organisms.

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Publication status

Exploratory record, not a reviewed medical publication.

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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.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

Dicloxacillin is a narrow-spectrum, penicillinase-resistant penicillin used primarily for infections caused by beta-lactamase-producing (penicillinase-producing) Staphylococcus aureus, such as skin and soft-tissue infections. NutriStack rates the supporting evidence as strong. Common adult dosing is Adults: 125-500 mg orally every 6 hours (typically 250-500 mg every 6 hours for skin/soft-tissue infection), taken 1 hour before or 2 hours after meals; maximum about 2 g/day in most outpatient regimens, though a prescriber sets the actual dose. With long-term use it can deplete vitamin k. This profile indexes 3 sources.

What it's good for

Skin and soft-tissue infections (cellulitis, impetigo, abscess, wound infection) due to methicillin-susceptible Staphylococcus aureus^1,2
Mild to moderate infections caused by penicillinase-producing staphylococci^2,1
Oral step-down therapy after parenteral antistaphylococcal treatment^2,3
Streptococcal skin infections (covers susceptible streptococci)^1,2

What to watch for

Nausea, vomiting, abdominal pain, and diarrhea
Rash and hypersensitivity reactions
Antibiotic-associated and Clostridioides difficile diarrhea/colitis
Known hypersensitivity to dicloxacillin, other penicillins, or any penicillin-class component^1,2
History of severe immediate (anaphylactic) reaction to penicillins or cephalosporins (cross-reactivity risk)

The bottom line

Evidence rating strong. Most-documented uses: skin and soft-tissue infections (cellulitis, impetigo, abscess, wound infection) due to methicillin-susceptible staphylococcus aureus, mild to moderate infections caused by penicillinase-producing staphylococci, oral step-down therapy after parenteral antistaphylococcal treatment. 3 sources indexed (1976–2019), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

Dicloxacillin is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to and inactivating penicillin-binding proteins (PBPs), the transpeptidase enzymes that cross-link peptidoglycan strands in the cell wall. Disruption of cross-linking weakens the wall and triggers autolytic enzymes, producing a bactericidal effect on dividing organisms. The isoxazolyl side chain provides steric protection against staphylococcal penicillinase (beta-lactamase), so the drug retains activity against penicillin-resistant but methicillin-susceptible staphylococci; resistance arises through altered PBP2a (mecA), the same mechanism that confers MRSA resistance.^1,2

Class

Antistaphylococcal penicillin (penicillinase-resistant penicillin)

Absorption

Best on an empty stomach

Dosing

Dosing & protocol.

Common range

Adults: 125-500 mg orally every 6 hours (typically 250-500 mg every 6 hours for skin/soft-tissue infection), taken 1 hour before or 2 hours after meals; maximum about 2 g/day in most outpatient regimens

Recommended form

Oral capsule (also available as oral suspension); take on an empty stomach with a full glass of water

Acid-stable and absorbed orally, but food markedly reduces and delays absorption. Take 1 hour before or 2 hours after meals with a full glass of water for best bioavailability. Highly protein-bound (about 95-98%) and primarily eliminated by renal and biliary routes.²

Depletions

What it depletes.

Nutrients this medication can lower over time, and what to replace.

Vitamin K

Mild

Like other broad-acting oral antibiotics, dicloxacillin can suppress vitamin K-producing (menaquinone-synthesizing) gut bacteria in the colon. In patients with already marginal dietary vitamin K intake or poor oral intake during illness, this can modestly reduce vitamin K status and prolong prothrombin time. The effect is generally minor with a narrow-spectrum antistaphylococcal penicillin used for short courses, but becomes clinically relevant in patients on warfarin or with poor nutritional reserves.

Monitor Prothrombin time / INR (especially in patients taking warfarin)Onset Typically only relevant after about 1 to 2 weeks of therapy, and primarily in patients with low dietary vitamin K intake or impaired absorption

Full Dicloxacillin depletion and interaction guide →

Safety

Full safety detail.

Side effects

Nausea, vomiting, abdominal pain, and diarrhea
Rash and hypersensitivity reactions
Antibiotic-associated and Clostridioides difficile diarrhea/colitis
Hepatotoxicity including cholestatic hepatitis (rare)
Eosinophilia and other blood dyscrasias (rare)
Interstitial nephritis (rare)
Anaphylaxis (rare but serious)

Contraindications

Known hypersensitivity to dicloxacillin, other penicillins, or any penicillin-class component^1,2
History of severe immediate (anaphylactic) reaction to penicillins or cephalosporins (cross-reactivity risk)
Not effective against and should not be used for MRSA or most gram-negative infections^1,3
Use caution in patients with significant hepatic impairment given potential for cholestatic injury

Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Reviews & position papers

1Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections (IDSA)PMIDStevens DL, et al. · Clinical Infectious Diseases · 2014
Beta-lactams active against MSSA, including antistaphylococcal penicillins, are first-line for non-purulent and MSSA purulent skin and soft-tissue infections.

Reference material

2Dicloxacillin Sodium Capsules - FDA Prescribing InformationU.S. Food and Drug Administration · FDA Label / DailyMed · 2019
Labeled for infections due to penicillinase-producing staphylococci; typical adult oral dose 125-500 mg every 6 hours taken on an empty stomach.
3Effect of food on the absorption of dicloxacillinClinical pharmacokinetics literature · Pharmacokinetics review · 1976
Concurrent food intake lowers peak serum concentrations and reduces bioavailability of dicloxacillin, supporting empty-stomach administration.

FAQ

Common questions.

Quick answers about Dicloxacillin, drawn from the data on this page.

What is Dicloxacillin?

What is Dicloxacillin used for?

Commonly cited benefits of Dicloxacillin include: Skin and soft-tissue infections (cellulitis, impetigo, abscess, wound infection) due to methicillin-susceptible Staphylococcus aureus; Mild to moderate infections caused by penicillinase-producing staphylococci; Oral step-down therapy after parenteral antistaphylococcal treatment; Streptococcal skin infections (covers susceptible streptococci). NutriStack rates the overall evidence as strong.

What is a typical dose of Dicloxacillin?

A typical adult dose of Dicloxacillin is Adults: 125-500 mg orally every 6 hours (typically 250-500 mg every 6 hours for skin/soft-tissue infection), taken 1 hour before or 2 hours after meals; maximum about 2 g/day in most outpatient regimens. The commonly recommended form is Oral capsule (also available as oral suspension); take on an empty stomach with a full glass of water. These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Dicloxacillin?

Reported side effects include nausea, vomiting, abdominal pain, and diarrhea, rash and hypersensitivity reactions, antibiotic-associated and clostridioides difficile diarrhea/colitis, hepatotoxicity including cholestatic hepatitis (rare), eosinophilia and other blood dyscrasias (rare), interstitial nephritis (rare). This is educational information; check with a healthcare professional before use.

How strong is the evidence for Dicloxacillin?

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

Dicloxacillin in NutriStack.

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