⚠️ Not suitable for serious or life-threatening infections because of unpredictable pharmacokinetics and lower potency compared to benzylpenicillin.

📖 About

Always check the BNF link here.

💊 Phenoxymethylpenicillin (Penicillin V) is similar to benzylpenicillin but is acid-stable and can be taken orally.
⬇️ Less active than benzylpenicillin → not recommended for severe infections.
🌍 Commonly used for streptococcal throat infections, prophylaxis in post-splenectomy patients, and rheumatic fever prevention.

⚡ Mechanism of Action

🔪 Bactericidal: interferes with bacterial cell wall synthesis.
Blocks formation of peptidoglycan cross-links, weakening the cell wall and causing lysis.

🧬 Spectrum of Activity

✅ Streptococci, Pneumococci, Meningococci.
✅ Treponema pallidum, Actinomyces israelii.
✅ Anaerobes of mouth/upper GI tract.
❌ Not reliable against gonococci or Bacteroides fragilis (lower bowel anaerobes).

🩺 Indications

📌 Prophylaxis post-splenectomy or after rheumatic fever.
👂 ENT infections: otitis media, tonsillitis, pharyngitis.
🦠 Skin/soft tissue infections: cellulitis, erysipelas.
Streptococcal throat infections (Group A Strep).

💊 Dosing – Phenoxymethylpenicillin (verify with BNF/datasheet)

Indication	Details
🦠 Acute Infections	Phenoxymethylpenicillin • 500 mg – 1 g PO every 6 h (QDS)
🛡️ Prophylaxis (e.g. post-splenectomy, rheumatic fever)	Phenoxymethylpenicillin • 250 mg PO BD

🔄 Interactions

See BNF – interactions are generally minimal but check carefully.
⬆️ Probenecid may increase serum levels (reduces renal clearance).
May reduce efficacy of the oral contraceptive pill (OCP).

⚠️ Cautions

🚨 Penicillin allergy (cross-reactivity with cephalosporins ~10%).
📉 Use with caution in severe renal impairment (dose adjustment may be needed).
Long-term prophylaxis should be reviewed regularly to reduce resistance risk.

🚫 Contraindications

Do not use for meningococcal or gonococcal infections.
Not recommended for severe/systemic infections – efficacy unpredictable.

💥 Side Effects

🫁 Allergic reactions: anaphylaxis, urticaria, rash, angioedema, fever.
🩸 Haematological: haemolytic anaemia, leucopenia, thrombocytopenia.
🩺 Renal: interstitial nephritis.
💩 Gastrointestinal: nausea, diarrhoea, antibiotic-associated colitis (rare).
Rare neurotoxicity (e.g. seizures) with very high doses.

📑 References

BNF: Phenoxymethylpenicillin
NICE guidance: Antibiotics for sore throat

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Phenoxymethylpenicillin (Penicillin V)