Mupirocin (Bactroban)
Is It Right for You?
A complete guide to Mupirocin (Bactroban) — what it treats, how it works, dosages, side effects, and when a clinician may prescribe it following an online consultation.
What Is Mupirocin (Bactroban)?
Mupirocin, marketed under the brand name Bactroban, is a topical antibiotic derived from Pseudomonas fluorescens. It is used for the treatment of superficial bacterial skin infections — primarily impetigo — and for the elimination of nasal carriage of Staphylococcus aureus, including meticillin-resistant Staphylococcus aureus (MRSA). Mupirocin has a unique mechanism of action entirely different from other antibiotic classes, meaning there is no cross-resistance between mupirocin and commonly used systemic antibiotics.
Available as a skin ointment (2%) and nasal ointment (2%), mupirocin is applied topically and is not absorbed systemically to any clinically significant degree. The skin ointment (Bactroban Skin Ointment) is used for infected skin conditions such as impetigo and secondarily infected wounds. The nasal ointment (Bactroban Nasal) is used specifically for MRSA nasal decolonisation in healthcare settings.
Mupirocin is a prescription-only medication in the UK. A licensed clinician must confirm the diagnosis and appropriateness before prescribing — which can now be done quickly and conveniently through a telehealth consultation.
What Conditions Is Mupirocin Used For?
Mupirocin skin ointment is prescribed for:
a highly contagious superficial bacterial skin infection caused by Staphylococcus aureus or Streptococcus pyogenes, presenting as honey-coloured crusted lesions, particularly on the face around the mouth and nose.
including infected wounds, abrasions, lacerations, insect bites, and eczema infected with susceptible bacteria.
elimination of MRSA carriage from the anterior nares (nostrils) as part of infection prevention protocols, particularly before surgery or in healthcare workers.
Mupirocin is applied topically and is not effective for systemic, bloodstream, or deep-tissue infections. It should not be applied near the eyes or ingested. The nasal ointment is exclusively for nasal use and must not be applied to skin or used near the eyes.
How Does Mupirocin Work?
Mupirocin has a unique antibacterial mechanism that distinguishes it from all other antibiotic classes. It reversibly and specifically inhibits the bacterial enzyme isoleucyl-tRNA synthetase — one of the aminoacyl-tRNA synthetases responsible for attaching the amino acid isoleucine to its corresponding transfer RNA molecule. This enzymatic step is essential for bacterial protein synthesis: without the correct loading of isoleucine onto tRNA, the ribosome cannot incorporate isoleucine into growing polypeptide chains.
By blocking this critical step, mupirocin causes depletion of intracellular isoleucine-charged tRNA, halting bacterial protein synthesis entirely. At the concentrations achieved by topical application, this produces a bactericidal effect against susceptible organisms. Crucially, mupirocin has very high selectivity for bacterial isoleucyl-tRNA synthetase over the corresponding mammalian enzyme, explaining its safety in topical use.
Mupirocin is highly active against Staphylococcus aureus (including most MRSA strains), Staphylococcus epidermidis, and Streptococcus pyogenes — the organisms most commonly responsible for impetigo and superficial skin infections. Its activity against gram-negative organisms is generally limited.
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 skin ointment: clean and dry the affected area before application. Apply a small amount and cover with a gauze dressing if desired, particularly for impetigo to prevent spread.
Wash hands before and after application unless the hands themselves are being treated.
For impetigo: softening and removing crusts with warm water before applying the ointment helps the antibiotic contact the underlying infected tissue more effectively.
For nasal ointment: apply approximately 0.5 cm of ointment to the inner surface of each nostril using a cotton bud or clean fingertip, then press the sides of the nose together and release repeatedly for a minute to distribute the ointment throughout the nasal passages.
Complete the full course — do not stop early if lesions appear to be clearing, as incompletely treated infections risk relapse and the development of resistance.
Avoid the eyes — mupirocin is not for ocular use. If accidental eye contact occurs, rinse thoroughly with water.
Side Effects of Mupirocin
Mupirocin is extremely well tolerated due to its negligible systemic absorption. Side effects are entirely local.
- Mild burning or stinging on application
- Skin dryness or itching
- Mild erythema (redness) at application site
- Nasal ointment: nasal irritation or congestion
- Contact dermatitis — allergic reaction to mupirocin or the ointment base (polyethylene glycol); worsening, spreading, or weeping of the skin condition rather than improvement
- Anaphylaxis — extremely rare systemic allergic reaction
Mupirocin ointment uses polyethylene glycol as its base. PEG can be absorbed through large, open wounds or damaged skin and may cause renal toxicity in patients with severely impaired renal function. Do not apply mupirocin to large areas of broken skin in patients with significant renal impairment.
Drug Interactions
No clinically significant systemic drug interactions have been reported with mupirocin ointment due to negligible systemic absorption. Concurrent use of other topical preparations on the same skin area is not recommended without clinical guidance.
May interfere with mupirocin’s absorption or dilute its concentration, potentially reducing antibacterial efficacy; concurrent use on the same area should be avoided unless advised.
In patients with extensive skin damage or renal impairment, absorption of PEG (present in some ointment formulations) may occur, potentially leading to accumulation; caution is advised.
May reduce the effectiveness of mupirocin if applied simultaneously by altering the local skin environment.
No clinically significant systemic interactions are expected due to negligible systemic absorption.
Important Warnings
Mupirocin resistance — both low-level and high-level — is an increasing concern, particularly in MRSA strains following repeated or prolonged courses of topical mupirocin. To preserve efficacy, mupirocin should be used for the shortest effective course and should not be used for non-infective skin conditions. Prolonged or repeated courses without confirmed bacterial infection contribute to resistance.
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Mupirocin skin ointment must not be applied to the eyes, inside the mouth, or swallowed. The nasal ointment is for nasal use only.
Mupirocin is considered safe for short-term topical use during pregnancy and breastfeeding, given its negligible systemic absorption. Avoid application to the nipple area before breastfeeding to prevent accidental ingestion by the infant.
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.
Mupirocin FAQs
Yes — mupirocin has excellent activity against most MRSA strains. This is significant because MRSA is resistant to many commonly used antibiotics including flucloxacillin and many oral penicillins. Mupirocin's unique mechanism means it is unaffected by the resistance mechanisms that make MRSA problematic for other antibiotics. However, high-level mupirocin resistance in MRSA is increasing and may limit its effectiveness in some cases.
Impetigo is highly contagious through direct contact with infected lesions or contaminated objects. Children with impetigo should be kept home from school or nursery until lesions have crusted over and dried, or for 48 hours after starting antibiotic treatment — whichever comes first. Cover lesions with a dressing if possible to reduce spread.
A dressing is not always required but is recommended for impetigo, as it reduces the risk of spreading infection to other people (particularly children) through direct contact. Gauze dressings are appropriate. Change the dressing at each application.
Mupirocin is not licensed or recommended as a treatment for acne vulgaris. Acne involves a different range of bacteria (primarily Cutibacterium acnes) that are not the primary targets of mupirocin, and using mupirocin for this purpose would contribute to antibiotic resistance without clinical benefit. Specific topical acne treatments (such as benzoyl peroxide or clindamycin) or oral antibiotics are more appropriate for acne.