Mupirocin (Bactroban Nasal)
Is It Right for You?
A complete guide to Mupirocin (Bactroban Nasal) — what it treats, how it works, dosages, side effects, and when a clinician may prescribe it following an online consultation.
What Is Mupirocin (Bactroban Nasal)?
Mupirocin, marketed as Bactroban Nasal 2% ointment, is a topical antibiotic derived from the bacterium Pseudomonas fluorescens. It belongs to a structurally unique antibiotic class — the pseudomonic acids — with a mechanism of action entirely distinct from all other antibiotic classes, meaning there is no cross-resistance with other antibiotics in clinical use. It is available as a 2% nasal ointment (Bactroban Nasal) specifically formulated for intranasal application, and separately as a 2% skin ointment (Bactroban) for cutaneous use.
Bactroban Nasal is the principal pharmacological agent used in the decolonisation of nasal Staphylococcus aureus carriage — including meticillin-resistant Staphylococcus aureus (MRSA). The anterior nares (nostrils) are the primary reservoir for both S. aureus and MRSA in colonised individuals, and nasal decolonisation is a key component of hospital infection control and pre-operative MRSA eradication protocols.
Mupirocin nasal ointment is a prescription-only medication in the UK. Its use should be directed by a clinician, ideally guided by microbiological culture and sensitivity results.
What Conditions Is Mupirocin Nasal Used For?
Mupirocin Nasal is indicated for:
eradication of MRSA carriage from the anterior nares as part of a comprehensive decolonisation protocol, typically alongside chlorhexidine body wash, in patients identified as MRSA carriers prior to surgery or other high-risk procedures
elimination of meticillin-sensitive S. aureus (MSSA) nasal carriage in recurrent S. aureus skin and soft tissue infections (furunculosis, impetigo, cellulitis) where the patient is identified as an endogenous source of repeated infection
pre-operative nasal decolonisation in MRSA-positive patients undergoing elective surgery (particularly orthopaedic and cardiac surgery) as part of national infection prevention guidelines
pre-operative nasal decolonisation in MRSA-positive patients undergoing elective surgery (particularly orthopaedic and cardiac surgery) as part of national infection prevention guidelines
Mupirocin nasal ointment is designed to eliminate asymptomatic nasal carriage of S. aureus and MRSA from the anterior nares. It is not indicated for the treatment of active bacterial rhinitis, sinusitis, or other active nasal infections, which require systemic antibiotics. Decolonisation should be guided by microbiological swab results and used as part of a comprehensive protocol that typically includes skin antisepsis with chlorhexidine wash.
How Does Mupirocin Work?
Mupirocin's antibiotic activity is based on a mechanism not shared by any other licensed antibiotic class — making it highly effective against organisms resistant to other agents:
Isoleucyl-tRNA synthetase inhibition: Mupirocin is a structural analogue of isoleucyl-adenylate — an intermediate in the aminoacylation reaction by which isoleucine is attached to its cognate transfer RNA (tRNA). Mupirocin binds with extremely high affinity and selectivity to bacterial isoleucyl-tRNA synthetase (IleRS), the enzyme responsible for this aminoacylation step.
Inhibition of bacterial protein synthesis: By occupying the active site of IleRS and preventing isoleucine incorporation into growing peptide chains, mupirocin causes depletion of isoleucyl-tRNA within the bacterial cell. This rapidly arrests protein synthesis, resulting in bacteriostatic or, at higher concentrations, bactericidal effects.
Selectivity: Mammalian isoleucyl-tRNA synthetase has a fundamentally different structure from its bacterial counterpart and is not significantly inhibited by mupirocin at therapeutic concentrations. This accounts for mupirocin's excellent local tolerability and safety profile.
Spectrum: Mupirocin is highly active against S. aureus (including MRSA), Streptococcus pyogenes, and coagulase-negative staphylococci. It has limited activity against gram-negative bacteria and anaerobes, which is why it is not used for systemic or broad-spectrum indications.
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
Apply correctly to ensure complete nasal coverage. Squeeze a small amount (approximately the size of a matchhead) from the tube or single-use pack into each nostril. Then press the sides of the nose gently together and release repeatedly for approximately one minute to spread the ointment throughout the anterior nasal passages.
Complete the full prescribed course. Even if a follow-up swab is to be taken after treatment, complete all doses as directed; incomplete courses are a primary driver of treatment failure and resistance.
Do not use for longer than 10 days. Prolonged use significantly increases the risk of selecting for mupirocin-resistant S. aureus, which can render the most important topical decolonisation agent ineffective.
Use as part of a complete decolonisation protocol. Nasal mupirocin alone is insufficient for MRSA decolonisation; it must be used in combination with a body wash antiseptic (typically chlorhexidine 4% daily body wash) and, if directed, topical treatment of other carriage sites (groin, axilla, perineum).
Avoid contact with eyes. If eye contact occurs, rinse thoroughly with water.
Side Effects of Mupirocin Nasal
Most side effects are mild and resolve on their own. Serious side effects are rare but require immediate medical attention.
- Nasal burning, stinging, or irritation on application --- common and usually mild; typically settles within a minute of application
- Rhinorrhoea (runny nose) or nasal dryness
- Headache
- Altered taste (dysgeusia) --- due to postnasal drainage of small amounts of ointment
- Severe hypersensitivity reactions --- including contact dermatitis, urticaria, and rare anaphylaxis; if any allergic reaction occurs, discontinue immediately and seek medical advice
- Mupirocin-resistant S. aureus --- not a side effect per se, but prolonged or repeated use selects for high-level mupirocin resistance (mediated by the mupA gene), rendering the agent ineffective; this is the most clinically important consequence of inappropriate mupirocin use
- Systemic absorption and toxicity --- mupirocin nasal ointment is formulated in a polyethylene glycol (PEG) base; PEG may be systemically absorbed through damaged nasal mucosa and can accumulate in patients with significant renal impairment; use with caution in severe renal insufficiency
High-level mupirocin resistance in S. aureus is increasingly prevalent and is directly linked to inappropriate, prolonged, or repeated use of mupirocin. Resistance renders decolonisation with mupirocin impossible, with significant implications for infection control. Mupirocin must only be used for the prescribed duration (maximum 10 days) and should not be used repeatedly without microbiological justification.
Drug Interactions
Always disclose all prescription drugs, over-the-counter medicines, vitamins, and supplements to your clinician or pharmacist before starting Mupirocin Nasal
avoid using other nasal ointments, sprays, or drops simultaneously in the same nostril as mupirocin, as they may physically dilute or displace the preparation, reducing its contact time and efficacy.
mupirocin nasal ointment is formulated in PEG; avoid mixing with other topical preparations at the application site.
Important Warnings
Prolonged mupirocin use is the primary driver of high-level mupirocin resistance in S. aureus. Treatment courses must not exceed 10 days. Repeated decolonisation attempts without microbiological evidence of eradication failure and sensitivity confirmation must be avoided.
The PEG base of Bactroban Nasal can be absorbed through mucosal surfaces and may accumulate in patients with severe renal impairment. Use with caution in patients with significantly reduced eGFR; consider alternative decolonisation strategies if renal function is severely compromised.
Nasal mupirocin alone does not achieve reliable MRSA eradication. All components of the decolonisation protocol — including daily chlorhexidine body wash for 5 days, treatment of other colonised sites, and environmental decontamination where relevant — must be completed simultaneously for optimal outcomes.
Systemic absorption from correctly applied nasal mupirocin is minimal. Use during pregnancy and breastfeeding is generally considered acceptable when clinically indicated; seek clinician guidance.
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 Nasal FAQs
S. aureus and MRSA colonise multiple body sites simultaneously — most commonly the nose, skin folds, groin, axillae, and perineum. Treating only the nasal carriage site while other body sites remain colonised results in rapid re-seeding of the nose. Chlorhexidine body wash eliminates skin carriage simultaneously, and the combination is substantially more effective than nasal mupirocin alone.
A follow-up microbiological nasal swab (and swabs from other carriage sites if indicated) is taken approximately 48 hours after completing the course. A negative result indicates successful eradication at the time of testing. Your clinician or infection control team will advise on the follow-up swabbing protocol.
Repeated courses of mupirocin significantly increase the risk of selecting mupirocin-resistant MRSA, which can render decolonisation impossible. Repeated MRSA carriage requires a specialist infection control or microbiology review before further mupirocin use, including confirmation of mupirocin sensitivity on culture.
No. The nasal formulation (Bactroban Nasal 2%) uses polyethylene glycol as its base, which is appropriate for mucosal surfaces. The skin ointment (Bactroban 2%) uses a different paraffin-based vehicle. The two formulations are not interchangeable — use only the correct formulation for the prescribed site.
Follow the full decolonisation protocol as directed by your clinical team — typically nasal mupirocin twice daily and chlorhexidine body wash daily for 5 days immediately before the operation. Complete all components of the protocol. Your clinical team will arrange a confirmatory swab before the procedure to verify eradication.