Fusidic Acid
Is It Right for You?
A complete guide to Fusidic Acid — what it treats, how it works, dosages, side effects, and when a clinician may prescribe it following an online consultation.
What Is Fusidic Acid?
Fusidic acid is a narrow-spectrum antibiotic derived from the fungus Fusidium coccineum. It has been in clinical use since the 1960s and remains an important treatment option for skin and soft tissue infections, particularly those caused by Staphylococcus aureus -- including strains that are resistant to some other antibiotics.
Unlike broad-spectrum antibiotics that target a wide range of bacteria, fusidic acid has a relatively narrow spectrum of activity, focused primarily on Gram-positive organisms and most notably staphylococci. This targeted activity makes it particularly valuable for skin infections, infected eczema, impetigo, and infected wounds where staphylococci are the most likely causative organism.
Fusidic acid is most commonly used in its topical form -- as a cream, ointment, or gel -- applied directly to the skin. It is also available as eye drops for bacterial conjunctivitis and as oral tablets for more serious systemic staphylococcal infections. Oral fusidic acid is always used in combination with another antibiotic to prevent the rapid development of resistance, which is a significant limitation of this drug when used alone.
Fusidic acid is available generically and under the brand name Fucidin. Combined formulations with a topical corticosteroid -- such as Fucidin H (fusidic acid with hydrocortisone) -- are also widely used for infected inflammatory skin conditions.
Topical fusidic acid is a prescription-only medication in the UK. It can be prescribed conveniently through a telehealth consultation with a licensed clinician who can assess whether it is appropriate for your skin condition.
What Conditions Is Fusidic Acid Used For?
Fusidic acid is used primarily for skin and soft tissue infections caused by susceptible staphylococci, as well as some other Gram-positive organisms:
a highly contagious superficial bacterial skin infection most commonly caused by Staphylococcus aureus or Streptococcus pyogenes; topical fusidic acid is a first-line treatment for localised impetigo.
eczema that has become secondarily infected with Staphylococcus aureus; often treated with Fucidin H (fusidic acid combined with hydrocortisone) to address both the infection and the underlying inflammation simultaneously.
minor cuts, grazes, and surgical wounds that have become infected with staphylococci or streptococci.
localised staphylococcal infections of hair follicles and surrounding tissue; topical fusidic acid may be used for small, superficial boils.
fusidic acid eye drops (Fucithalmic) are used to treat bacterial eye infections, particularly those caused by staphylococci; the viscous gel formulation allows twice-daily dosing.
Fusidic acid is active primarily against Gram-positive bacteria, particularly staphylococci. It has no meaningful activity against Gram-negative bacteria or anaerobes. It is not appropriate for most chest infections, urinary tract infections, or gastrointestinal infections. A clinician will assess whether your infection is likely to be caused by an organism susceptible to fusidic acid before prescribing.
How Does Fusidic Acid Work?
Fusidic acid has a unique mechanism of action that distinguishes it from all other classes of antibiotics currently in clinical use. It works by inhibiting bacterial protein synthesis at a highly specific step in the elongation cycle of translation.
During protein synthesis, ribosomes move along messenger RNA and assemble amino acids into proteins. This process requires a protein called elongation factor G (EF-G), which facilitates the movement (translocation) of the ribosome along the mRNA strand after each amino acid is added. Fusidic acid binds to EF-G and stabilises the EF-G/ribosome complex in a state that prevents EF-G from detaching from the ribosome after translocation. This effectively locks the ribosome in place, halting further protein synthesis.
Without the ability to synthesise new proteins, bacteria cannot grow, divide, or produce the enzymes and structural components they need to survive. This results in a bacteriostatic effect (inhibiting bacterial growth) at lower concentrations and a bactericidal effect (killing bacteria) at the higher concentrations achieved in infected tissues with topical application.
Fusidic acid's unique binding site on EF-G means there is no cross-resistance with any other class of antibiotic -- bacteria resistant to penicillins, macrolides, tetracyclines, or fluoroquinolones remain fully susceptible to fusidic acid (provided they have not acquired specific fusidic acid resistance mechanisms). However, resistance to fusidic acid itself can develop rapidly through a single point mutation in the EF-G gene, which is why oral fusidic acid is always combined with a second antibiotic, and why topical fusidic acid should not be used for extended periods without clinical review.
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
For topical creams and ointments: apply a thin layer to the affected area only, covering it lightly if needed. Do not apply to large areas of skin or under occlusive dressings unless directed, as this increases systemic absorption. Wash hands before and after application.
Do not use topical fusidic acid for longer than 7 days unless specifically directed by your clinician. Prolonged topical use is a major driver of fusidic acid resistance in the community, particularly for Staphylococcus aureus. If the skin has not improved after 7 days, return to your clinician for reassessment rather than continuing treatment.
For eye drops (Fucithalmic): tilt your head back, pull down the lower eyelid, and apply one drop into the eye. Blink gently to spread the gel. Avoid touching the tip of the dropper to the eye or any surface. If wearing contact lenses, remove them before application and wait at least 15 minutes before reinserting.
Oral fusidic acid must always be taken with food to reduce gastrointestinal side effects, particularly nausea and abdominal discomfort. It must always be taken alongside a second antibiotic as directed by your clinician -- never as a monotherapy for systemic infections.
Complete the full prescribed course for both topical and oral treatment, even if symptoms improve before the course is finished.
Side Effects of Fusidic Acid
Topical fusidic acid is generally very well tolerated with minimal systemic absorption and few side effects. Oral fusidic acid has a more notable side effect profile, particularly affecting the gastrointestinal system and liver.
- Mild skin irritation, burning, or stinging at the application site
- Skin redness or itching
- Contact dermatitis (allergic reaction to the cream) -- uncommon
- Eye irritation, blurred vision, or watering (with eye drops)
- Nausea and vomiting
- Abdominal pain or discomfort
- Diarrhoea
- Elevated liver enzymes (usually reversible on stopping treatment)
- Jaundice -- particularly with higher doses or prolonged use
- Hepatotoxicity -- significant liver damage characterised by jaundice, dark urine, pale stools, severe fatigue, and right upper abdominal pain; most associated with oral and intravenous use, particularly at high doses or with prolonged treatment; liver function should be monitored during extended oral courses
- Severe allergic reaction -- urticaria, facial swelling, difficulty breathing; rare but requires immediate emergency treatment
- Severe skin reactions -- Stevens-Johnson Syndrome; very rare
- Haematological effects -- anaemia, leucopenia; rare; associated with prolonged oral or intravenous use
- Reversible jaundice in neonates -- fusidic acid can displace bilirubin from protein-binding sites; of particular relevance in premature infants
Oral fusidic acid has a well-documented association with hepatotoxicity, particularly at higher doses and with prolonged use. Liver function tests should be performed before starting oral treatment and monitored regularly during extended courses. Any symptoms of liver dysfunction -- including jaundice, dark urine, or severe fatigue -- should be reported to a clinician immediately.
Drug Interactions
Fusidic acid has fewer drug interactions than many other antibiotics, particularly in its topical form. Oral fusidic acid has several clinically relevant interactions. Always disclose all medications to your clinician or pharmacist before starting treatment.
The combination of oral fusidic acid with statins is associated with a significantly increased risk of rhabdomyolysis -- severe muscle breakdown that can cause acute kidney injury and be life-threatening. This interaction is well documented and potentially fatal. Statins should be suspended for the duration of oral fusidic acid treatment and restarted after a suitable washout period. Patients must inform their clinician if they are taking any statin medication before oral fusidic acid is prescribed.
Oral fusidic acid may enhance the anticoagulant effect of warfarin, increasing bleeding risk. INR should be monitored closely during concurrent use.
Fusidic acid may increase ciclosporin blood levels, raising the risk of nephrotoxicity and other ciclosporin-related adverse effects. Monitoring of ciclosporin levels is advisable.
Colestyramine may reduce the oral absorption of fusidic acid. Separate administration by at least 2 hours.
Important Warnings
The combination of oral fusidic acid with any statin is associated with a serious risk of rhabdomyolysis -- a breakdown of muscle tissue that releases proteins into the bloodstream, which can cause acute kidney injury, cardiac complications, and in severe cases, death. This interaction is predictable and well-documented. Statins must be suspended before starting oral fusidic acid and not restarted until an appropriate interval after the course is completed. Always inform your clinician and pharmacist of all medications you are taking, including statins
Oral fusidic acid is associated with a risk of serious liver toxicity, particularly at higher doses and with prolonged courses. Patients should be monitored with liver function tests before and during treatment. Any symptoms suggesting liver dysfunction -- jaundice, dark urine, pale stools, severe fatigue, or right-sided abdominal pain -- require immediate cessation of treatment and urgent medical review.
Fusidic acid resistance develops rapidly when it is used as a monotherapy for systemic infections -- a single point mutation in the target gene (EF-G) is sufficient to confer high-level resistance. For this reason, oral fusidic acid must always be prescribed alongside a second antibiotic. Topical fusidic acid should not be used for prolonged periods, as community resistance rates among Staphylococcus aureus have increased significantly in areas of heavy topical use. Always use topical fusidic acid for the shortest effective duration.
Topical fusidic acid should only be applied to the affected area and not used over large areas of skin or under occlusive dressings (unless clinically directed), as increased absorption can lead to systemic effects and liver toxicity.
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.
Fusidic Acid FAQs
Yes. A licensed clinician can assess your skin condition or infection via a telehealth consultation and prescribe fusidic acid cream, ointment, eye drops, or oral tablets if clinically appropriate. For common conditions such as impetigo, infected eczema, and folliculitis, prescriptions are typically issued the same day.
Most patients notice an improvement in their skin infection within 2--3 days of starting topical fusidic acid. Impetigo sores typically begin to dry and crust over within 48--72 hours. The full course of 5--7 days should be completed even if the skin looks clear beforehand, to ensure the infection is fully eradicated and reduce the risk of recurrence.
Fucidin H is a combination product containing fusidic acid (antibiotic) and hydrocortisone (a mild corticosteroid). It is used when a skin condition has both an infective component and an inflammatory component -- most commonly infected eczema. The fusidic acid treats the bacterial infection while the hydrocortisone reduces redness, swelling, and itching. It should only be used for short courses (5--7 days) as prolonged use of topical corticosteroids carries risks including skin thinning.
Yes. Topical fusidic acid is commonly used to treat impetigo in children and is generally well tolerated. It should be applied three times daily for 5--7 days. Impetigo is highly contagious -- children should avoid school or nursery until the sores have crusted over or 48 hours after starting antibiotic treatment, and good hand hygiene is essential to prevent spread within the household
Prolonged use of topical fusidic acid is one of the main drivers of antibiotic resistance in Staphylococcus aureus in the community. Resistance can develop quickly when the antibiotic is used repeatedly or for extended periods, meaning it may no longer work when needed in the future. If your skin condition has not improved after 7 days, consult your clinician for reassessment rather than continuing treatment independently.
No. Contact lenses should not be worn during treatment with fusidic acid eye drops (Fucithalmic). Remove lenses before applying the drops and wait at least 15 minutes before reinserting them. The preservatives in eye drops can be absorbed by soft contact lenses and cause eye irritation.
This is a very important safety concern. Oral fusidic acid combined with statins carries a well-documented risk of rhabdomyolysis -- a serious and potentially life-threatening breakdown of muscle tissue. If you take any statin (such as atorvastatin, simvastatin, or rosuvastatin), your clinician must be made aware before oral fusidic acid is prescribed. In most cases, the statin will need to be temporarily suspended for the duration of treatment. Topical fusidic acid (cream or eye drops) does not carry this risk due to negligible systemic absorption.