Fucidin (Fusidic Acid):
Is It Right for You?
A complete guide to Fucidin (Fusidic Acid) — what it treats, how it works, dosages, side effects, and when a clinician may prescribe it following an online consultation.
What Is Fucidin?
Fucidin is the brand name for fusidic acid, a narrow-spectrum antibiotic with potent activity specifically against staphylococcal species, including meticillin-sensitive Staphylococcus aureus (MSSA). It is available in multiple formulations: oral tablets (250 mg), oral suspension (250 mg/5 mL), topical cream 2%, topical ointment 2%, and combined formulations with hydrocortisone (Fucidin H — fusidic acid 2% / hydrocortisone 1% cream) for infected eczema and inflammatory skin conditions with secondary bacterial infection. Fusidic acid has a unique mechanism of action — unrelated to any other antibiotic class — and excellent penetration into skin, soft tissue, and bone, making it valuable for superficial skin infections, impetigo, infected eczema, and — in oral form under specialist guidance — bone and joint infections caused by susceptible staphylococci. Fucidin (all formulations) is a prescription-only medication in the UK. Appropriate use and restriction is essential to preserve fusidic acid's activity against S. aureus, as resistance can emerge rapidly with inappropriate or prolonged use.
What Conditions Is Fucidin Used For?
Fucidin is indicated for:
staphylococcal pneumonia, particularly post-influenza pneumonia where S. aureus is a known risk.
including bacterial bronchitis and mild community-acquired pneumonia caused by susceptible organisms.
Resistance to fusidic acid emerges rapidly when it is used as monotherapy for systemic infections — typically within days of starting treatment. For all systemic or serious staphylococcal infections, fusidic acid must be used in combination with another anti-staphylococcal antibiotic (typically flucloxacillin or rifampicin) to suppress the emergence of resistance.
How Does Fucidin Work?
Fusidic acid's mechanism of action is entirely distinct from all other antibiotics in clinical use, and its selective activity against staphylococci reflects its unique molecular target: Elongation factor G (EF-G) inhibition: During bacterial protein synthesis, the ribosome moves along mRNA by a process called translocation, which requires the binding and hydrolysis of GTP by elongation factor G (EF-G). Fusidic acid forms a stable complex with the ribosome–EF-G–GDP structure after GTP hydrolysis, locking EF-G in its post-translocation conformation and preventing its release from the ribosome. This traps the ribosome in an immobile state, arresting translocation and halting protein synthesis. Bacteriostatic and bactericidal activity: At the concentrations typically achieved at skin infection sites, fusidic acid is bacteriostatic against staphylococci. At higher concentrations (as may be achieved in bone with oral dosing), it can be bactericidal. Staphylococcal selectivity: Fusidic acid has very high intrinsic activity against S. aureus (including MRSA) and other staphylococci because their EF-G is highly sensitive to fusidic acid binding. EF-G in gram-negative bacteria is substantially less sensitive, explaining the narrow gram-positive spectrum.
Dosages & Administration
The correct dose depends on the type and severity of infection, age, weight, and kidney function. Always follow your clinician's instructions. The table below is for general reference only.
Administration Tips
Always follow your clinician's instructions. Dosing and duration depend critically on indication and formulation. Topical cream / ointment 2% (impetigo, skin infections): Apply small amount to affected area 3 times daily for 5–7 days; maximum 10 days. Fucidin H cream (infected eczema with inflammation): Apply thin layer to affected area 3 times daily for a maximum of 2 weeks. Oral tablets (systemic staphylococcal infections — in combination): 500–1000 mg per dose three times daily as directed by specialist; typically 2–6 weeks.
Side Effects of Fucidin
Common Side Effects (Topical)
- Local skin reactions --- itching, burning, or redness at the application site; mild and usually transient
- Contact sensitisation --- particularly with prolonged use; may present as worsening of the skin condition
- Hepatotoxicity --- jaundice, raised liver enzymes, and hepatic dysfunction; more common with oral therapy; monitor liver function in patients on prolonged systemic courses
- Severe hypersensitivity reactions --- anaphylaxis or severe contact dermatitis; rare
- Reversible jaundice --- associated with intravenous fusidic acid, particularly with rapid infusion; must be given slowly via IV if used in hospital settings
- Haemolysis --- rare; reported in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency
Resistance to fusidic acid in S. aureus can emerge within days of monotherapy exposure. Short topical courses (maximum 10 days) for appropriate localised indications are essential to prevent resistance selection. Inappropriate use of topical fucidin for non-bacterial conditions, prolonged repeated courses, and sharing of topical fucidin are significant drivers of community fusidic acid resistance, which undermines its effectiveness for all patients.
Drug Interactions
[MAJOR] HMG-CoA reductase inhibitors (statins) --- fusidic acid (oral) inhibits statin metabolism, causing dramatic increases in statin plasma concentrations and a markedly elevated risk of rhabdomyolysis (severe muscle breakdown); all statins must be discontinued before starting systemic fusidic acid and must not be restarted until at least 7 days after the fusidic acid course has completed. [MODERATE] Anticoagulants (warfarin) --- oral fusidic acid may increase the anticoagulant effect of warfarin; monitor INR closely during and after treatment. [MODERATE] Ciclosporin --- fusidic acid may increase ciclosporin plasma levels; monitor ciclosporin concentrations. [MINOR] Topical formulations --- no clinically significant systemic drug interactions at standard topical doses due to negligible systemic absorption from correctly applied skin preparations.
Doxycycline may increase ciclosporin blood levels, potentially causing toxicity. Close monitoring is required if both are prescribed simultaneously.
Concurrent use of desloratadine with central nervous system depressants such as benzodiazepines, sleeping tablets, or certain pain medications may increase sedative effects. Use with caution and inform your clinician of all medications you are taking.
Concurrent use reduces azithromycin absorption. Space doses at least 2 hours apart from antacid use.
Probenecid reduces the kidney excretion of phenoxymethylpenicillin, leading to higher and more sustained blood levels of the antibiotic. This interaction may occasionally be used intentionally but should only occur under medical supervision.
There is a theoretical risk that phenoxymethylpenicillin may reduce the effectiveness of combined oral contraceptives by affecting gut bacteria involved in oestrogen recycling. The clinical evidence is limited, but using additional contraceptive precautions during treatment is a reasonable precaution.
Important Warnings
Desloratadine is not appropriate for treating anaphylaxis or severe allergic emergencies. If you are at risk of anaphylaxis, your clinician will prescribe an adrenaline auto-injector (such as an EpiPen) as your primary emergency treatment. Desloratadine may be taken alongside this for ongoing symptom management but cannot replace emergency treatment.
Doxycycline passes into breast milk and may affect the developing teeth and bones of nursing infants. It is generally not recommended during breastfeeding. A clinician will advise on safe alternatives if needed.
Speak to a Clinician About Treatment
Getting advice no longer means sitting in a waiting room. Through The GP Service, you can consult with a licensed clinician in minutes — from home, on your lunch break, or wherever works for you. If treatment is clinically appropriate, your clinician can issue a prescription during the consultation. A consultation does not guarantee a prescription.
The treatment you need, when you need it.
Fucidin FAQs
Amoxicillin is generally considered safe for use during pregnancy based on available evidence. Always consult your clinician before taking any medication while pregnant or breastfeeding.
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed one and continue as normal. Never take a double dose to make up for a missed one. For malaria prophylaxis, consistency is especially important – if you miss a dose, take it as soon as you remember and continue daily.
Yes. For conditions such as perennial allergic rhinitis or chronic urticaria, desloratadine is safe for continuous daily use over extended periods. Your clinician will review your treatment periodically to ensure it remains appropriate and effective.
Azithromycin is rapidly absorbed and begins working within a few hours of the first dose. Most patients notice an improvement in symptoms within 24 to 48 hours. Importantly, azithromycin continues to work for several days after the last dose is taken, due to its long half-life and high tissue concentrations.
Nitrofurantoin is generally considered safe during the first and second trimesters of pregnancy and is commonly prescribed for UTIs during this period. However, it should be avoided in the final weeks of pregnancy (from 38 weeks onwards) due to the risk of haemolytic anaemia in the newborn. Always consult your clinician before starting any medication during pregnancy.