Bactroban: Uses, Dosage & Side Effects
A topical antibiotic ointment containing mupirocin, used to treat bacterial skin infections including impetigo
Bactroban (mupirocin) is a prescription topical antibiotic ointment applied directly to the skin to treat bacterial infections, most notably impetigo. It works by inhibiting bacterial protein synthesis through a unique mechanism of action, making it effective against common skin pathogens including Staphylococcus aureus (including MRSA strains) and Streptococcus pyogenes. Bactroban is typically applied two to three times daily for up to 10 days and is available as a 2% ointment.
Quick Facts: Bactroban
Key Takeaways
- Bactroban contains mupirocin 2%, a topical antibiotic that works by inhibiting bacterial protein synthesis through a unique mechanism not shared by other antibiotic classes.
- It is primarily prescribed for impetigo and other superficial bacterial skin infections caused by Staphylococcus aureus and Streptococcus pyogenes.
- Apply a small amount to the affected area two to three times daily for up to 10 days; the treated area may be covered with a bandage if desired.
- Mupirocin retains activity against MRSA (methicillin-resistant Staphylococcus aureus), making it a valuable option for resistant skin infections.
- Avoid applying Bactroban ointment to eyes, nostrils, or large open wounds, and discontinue use immediately if a hypersensitivity reaction occurs.
What Is Bactroban and What Is It Used For?
Bactroban (mupirocin) is a topical antibacterial agent that belongs to a unique class of antibiotics derived from Pseudomonas fluorescens. Unlike most other antibiotics, mupirocin has a novel mechanism of action: it reversibly binds to bacterial isoleucyl-transfer RNA synthetase (IleRS), preventing the incorporation of isoleucine into bacterial proteins. This effectively halts bacterial protein synthesis and, at therapeutic concentrations applied to the skin, leads to bactericidal activity against susceptible organisms.
The primary indication for Bactroban ointment is the treatment of impetigo (commonly known as school sores), a highly contagious superficial skin infection most frequently caused by Staphylococcus aureus or Streptococcus pyogenes. Impetigo is especially common in children aged 2 to 5 years, though it can affect individuals of any age. The infection presents as red sores that rupture, ooze, and form a characteristic honey-colored crust. Bactroban is highly effective against these causative organisms and is recommended as a first-line topical treatment for localized impetigo by international dermatology and infectious disease guidelines.
Beyond impetigo, Bactroban is used for other superficial bacterial skin infections, including folliculitis (infection of hair follicles), furunculosis (boils), and secondarily infected wounds such as minor cuts, abrasions, and insect bites. In clinical trials, mupirocin has demonstrated cure rates of approximately 90-95% for primary skin infections caused by susceptible bacteria. Its topical route of administration means that systemic side effects are extremely rare, as the drug is minimally absorbed through intact or broken skin and is rapidly metabolized to the inactive metabolite monic acid upon absorption.
An important clinical advantage of mupirocin is its activity against methicillin-resistant Staphylococcus aureus (MRSA). Because mupirocin targets a different enzyme than beta-lactam antibiotics, it retains full efficacy against MRSA strains. This has made Bactroban (particularly the nasal formulation) a cornerstone of MRSA decolonization protocols in hospitals and healthcare settings worldwide. The World Health Organization (WHO) has included mupirocin on its Model List of Essential Medicines, underscoring its importance in global healthcare.
Bactroban is available as a 2% ointment in a polyethylene glycol (macrogol) base. The standard formulation comes in 15-gram aluminium tubes. A separate nasal formulation (Bactroban Nasal) exists specifically for intranasal use and contains a different base (paraffin-based) suitable for application inside the nostrils. It is crucial not to interchange these two formulations, as the ointment base differs significantly between them.
What Should You Know Before Using Bactroban?
Contraindications
The primary contraindication for Bactroban is a known hypersensitivity to mupirocin or any of the excipients in the ointment formulation. The ointment base contains macrogols (polyethylene glycols), and patients with a known allergy to these compounds should not use Bactroban. If you have experienced an allergic reaction to mupirocin in the past, such as skin rash, hives, swelling, or difficulty breathing, you must inform your healthcare provider before starting treatment.
Bactroban ointment is formulated exclusively for external use on the skin. It must not be applied to the eyes, inside the nostrils (unless using the specific nasal formulation), or to any mucous membranes. If the ointment accidentally comes into contact with the eyes, rinse the area thoroughly with clean water and seek medical advice if irritation persists. The skin ointment formulation should never be used intranasally, as the macrogol base is not suitable for mucosal application.
Warnings and Precautions
If a hypersensitivity reaction or severe local irritation develops during use, discontinue Bactroban immediately, wash the ointment off, and contact your healthcare provider. Seek emergency medical attention if you experience swelling of the face, tongue, or throat, difficulty swallowing, hives, or difficulty breathing, as these may indicate anaphylaxis.
Macrogol absorption: Bactroban ointment contains macrogols (polyethylene glycols) as its base. These compounds can be absorbed through open wounds and damaged skin. Once absorbed, macrogols are excreted by the kidneys. Therefore, Bactroban ointment should not be applied to large areas of open or damaged skin, particularly in patients with impaired kidney function. In such cases, macrogol accumulation could potentially lead to renal toxicity. Healthcare providers should carefully assess the extent of skin damage and the patient's renal function before prescribing Bactroban for use on extensive wounds.
Antibiotic resistance: As with all antibacterial agents, prolonged or repeated use of Bactroban may lead to the selection and overgrowth of non-susceptible organisms, including fungi. If there is no clinical improvement after 5 days of treatment, or if the infection appears to be worsening, the diagnosis and treatment should be reassessed. Mupirocin resistance, particularly high-level resistance mediated by the mupA gene, has been documented and is a growing concern in healthcare settings. To minimize resistance development, Bactroban should only be used for the prescribed duration and indication.
Diarrhea: Although rare with topical use, if prolonged or severe diarrhea develops during or after treatment with Bactroban, discontinue the medication and consult your healthcare provider. This could indicate a secondary gastrointestinal infection, including Clostridioides difficile-associated disease, although this is exceedingly uncommon with topical antibiotics.
Concomitant topical products: If you are using other topical medications on the same area of skin, avoid applying them at the same time as Bactroban. Other products may interfere with the absorption and efficacy of mupirocin. Allow adequate time between applications of different topical agents, and follow your healthcare provider's instructions regarding timing.
Pregnancy and Breastfeeding
Pregnancy: There is limited clinical experience with Bactroban use during pregnancy. Animal reproductive studies with mupirocin have not demonstrated adverse effects on the fetus, but adequate and well-controlled studies in pregnant women are lacking. As a precaution, Bactroban should only be used during pregnancy if the potential benefit to the mother justifies the potential risk to the fetus. The minimal systemic absorption of topical mupirocin suggests a low risk, but consultation with a healthcare provider is essential before use during pregnancy.
Breastfeeding: It is not known whether mupirocin is excreted in human breast milk. Given the minimal systemic absorption following topical application, significant concentrations in breast milk are considered unlikely. However, as a precautionary measure, consult your healthcare provider before regular use of Bactroban during breastfeeding. If treating a cracked nipple, the ointment must be thoroughly washed off before nursing the infant to prevent oral ingestion by the baby.
Driving and Operating Machinery
Bactroban has no known effect on the ability to drive or operate machinery. The topical route of administration results in negligible systemic absorption, and no central nervous system effects have been reported. Patients can safely continue their normal daily activities, including driving, while using Bactroban.
How Does Bactroban Interact with Other Drugs?
Because Bactroban is applied topically and undergoes minimal systemic absorption, clinically significant drug-drug interactions with oral or injectable medications are extremely rare. Mupirocin acts locally at the site of application, and the small amounts that may be absorbed through the skin are rapidly metabolized to the inactive metabolite monic acid. This means that Bactroban does not significantly affect the blood levels or activity of other systemically administered drugs.
However, there are important considerations regarding the concomitant use of other topical products on the same area of skin. Applying other creams, ointments, or lotions to the same site as Bactroban may dilute the antibiotic, alter its absorption characteristics, or create a physical barrier that reduces its effectiveness. For this reason, if multiple topical treatments are required on the same area, they should be applied at different times rather than simultaneously.
In vitro studies have demonstrated that chloramphenicol, when applied topically in combination with mupirocin, may interfere with the antibacterial activity of mupirocin. This is because chloramphenicol also affects bacterial protein synthesis and may compete with mupirocin at the ribosomal level, although the clinical significance of this interaction in topical use is not well established. As a general principle, combining two topical antibiotics on the same area is rarely necessary and should only be done under medical supervision.
There are no known interactions between Bactroban and oral antibiotics, analgesics, anti-inflammatory drugs, or any other systemically administered medications. Patients taking warfarin, metformin, blood pressure medications, or any other chronic oral therapies do not need dose adjustments when using Bactroban ointment. Similarly, Bactroban does not interact with hormonal contraceptives, immunosuppressants, or chemotherapy agents when used topically as directed.
| Interacting Substance | Type | Effect | Recommendation |
|---|---|---|---|
| Chloramphenicol (topical) | Pharmacodynamic | May reduce mupirocin antibacterial activity | Avoid concurrent topical use on same area |
| Other topical antibiotics | Pharmacokinetic | May alter absorption or dilute concentration | Apply at different times if both are needed |
| Emollients, moisturizers | Physical | May create a barrier reducing mupirocin penetration | Apply separately; allow time between applications |
| Topical corticosteroids | Physical | May alter local immune response and skin absorption | Use as directed by healthcare provider; stagger applications |
| Oral medications (general) | None | No clinically significant systemic interactions | No dose adjustments required |
What Is the Correct Dosage of Bactroban?
Always use Bactroban exactly as prescribed by your healthcare provider or as directed by your pharmacist. The dosage and duration of treatment may vary depending on the type and severity of the skin infection, but the standard regimen for adults and children is well established and consistent across international guidelines.
Adults
Standard Adult Dosage
Apply a small amount of Bactroban 2% ointment to the affected area 2 to 3 times daily for up to 10 days. Wash your hands thoroughly before and after each application. The treated area may be covered with a sterile bandage or dressing if desired. Do not use Bactroban for longer than the period recommended by your healthcare provider.
When applying Bactroban, first clean the affected area gently with mild soap and water, then pat it dry. Using a clean fingertip or a sterile cotton swab, apply a thin layer of ointment over the entire infected area and a small margin of surrounding healthy skin. If the infection involves a crusted lesion (as in impetigo), the crusts may be softened and gently removed before application to allow better penetration of the antibiotic.
Children
Pediatric Dosage
The dosage for children is the same as for adults: apply a small amount of Bactroban 2% ointment to the affected area 2 to 3 times daily for up to 10 days. Bactroban is considered safe for use in children of all ages, including infants, under the supervision of a healthcare provider. Parents or caregivers should apply the ointment and ensure the child does not ingest it or rub it into the eyes.
For children, it is especially important to keep the treated area covered with a bandage when possible, both to protect the wound and to prevent the child from touching or licking the ointment. Impetigo is highly contagious among children in daycare and school settings, so maintaining good hand hygiene and keeping the child's skin clean are essential adjunctive measures during treatment.
Elderly
Elderly Patient Dosage
No dosage adjustment is required for elderly patients. Apply Bactroban 2% ointment as directed: 2 to 3 times daily for up to 10 days. However, elderly patients may have thinner skin and reduced renal function. Extra caution should be exercised when applying Bactroban to large areas of damaged or open skin in elderly patients, as macrogol absorption may be increased.
Missed Dose
If you forget to apply Bactroban at the scheduled time, apply it as soon as you remember. Then continue with your regular application schedule. Do not apply a double amount to make up for a missed application. If it is almost time for your next scheduled application, skip the missed dose and continue as normal. Consistency is important for maintaining effective local antibiotic concentrations, so try to apply the ointment at evenly spaced intervals throughout the day.
Overdose
If you have applied significantly more Bactroban than directed, or if the ointment has been accidentally swallowed (particularly by a child), contact your healthcare provider, hospital emergency department, or poison control center immediately for assessment and advice.
Topical overdose with Bactroban is unlikely to cause significant systemic toxicity due to the minimal absorption of mupirocin through the skin. However, accidental oral ingestion of the ointment is a concern, particularly in young children. The macrogol (polyethylene glycol) base can cause gastrointestinal symptoms such as nausea, vomiting, and diarrhea if swallowed. In patients with impaired kidney function, accidental ingestion of a large amount of ointment may warrant monitoring of renal function, as macrogols are excreted by the kidneys and could accumulate in renally impaired individuals.
There is no specific antidote for mupirocin overdose. Treatment is supportive and symptom-based. In the event of accidental ingestion, medical professionals may consider gastric decontamination if presentation is early and the amount ingested is substantial.
| Patient Group | Dosage | Frequency | Duration | Special Notes |
|---|---|---|---|---|
| Adults | Small amount (thin layer) | 2-3 times daily | Up to 10 days | May cover with bandage |
| Children (all ages) | Small amount (thin layer) | 2-3 times daily | Up to 10 days | Supervise application; keep covered |
| Elderly | Small amount (thin layer) | 2-3 times daily | Up to 10 days | Caution with large open wounds and renal impairment |
| Renal impairment | Small amount (thin layer) | 2-3 times daily | Up to 10 days | Avoid large areas of open/damaged skin; monitor renal function |
What Are the Side Effects of Bactroban?
Like all medicines, Bactroban can cause side effects, although not everyone will experience them. Because Bactroban is applied topically and very little of the active ingredient is absorbed into the bloodstream, side effects are generally limited to the area of application. Most side effects are mild, transient, and resolve without the need for additional treatment. However, some patients may experience more significant reactions that require medical attention.
Stop using Bactroban and contact your doctor immediately or go to the nearest emergency department if you experience: swelling of the face, tongue, or throat; difficulty swallowing; hives or widespread skin rash; difficulty breathing. These symptoms may indicate angioedema or anaphylaxis, which are very rare but potentially life-threatening allergic reactions.
Common
May affect up to 1 in 10 people
- Burning sensation at the application site
- Stinging or pain at the application site
Uncommon
May affect up to 1 in 100 people
- Redness (erythema) at the application site
- Itching (pruritus) at the application site
- Stinging or tingling sensation
- Dry skin at the application site
- Contact dermatitis (sensitization to mupirocin or the ointment base)
Very Rare
May affect up to 1 in 10,000 people
- Generalized allergic reactions (systemic hypersensitivity including rash, urticaria)
- Angioedema (swelling of face, lips, tongue, or throat)
- Anaphylaxis (severe, life-threatening allergic reaction)
The burning sensation at the application site is the most frequently reported side effect, occurring in approximately 1-3% of patients in clinical trials. This is usually mild, temporary, and diminishes with continued use. If the burning is severe or persistent, consult your healthcare provider about whether to continue treatment.
Contact sensitization (an allergic skin reaction to the drug or its base) is uncommon but has been reported. If you develop increasing redness, swelling, or itching at the application site that worsens rather than improves over time, this may indicate a local allergic reaction rather than a normal side effect. Discontinue use and consult your healthcare provider for an alternative treatment.
Because mupirocin has minimal systemic absorption, systemic side effects such as headache, nausea, gastrointestinal disturbances, or effects on other organ systems are not expected with normal topical use. The safety profile of Bactroban has been well established through decades of clinical use worldwide, and it remains one of the safest topical antibiotics available.
If you experience any side effects, including those not listed here, report them to your healthcare provider. You can also report side effects directly to your national pharmacovigilance authority (for example, the FDA MedWatch program in the United States or the Yellow Card Scheme in the United Kingdom). Reporting side effects helps to continuously monitor the benefit-risk profile of medicines.
How Should You Store Bactroban?
Proper storage of Bactroban is important to maintain the ointment's effectiveness and safety throughout its shelf life. The following storage guidelines should be observed:
- Temperature: Store at or below 25°C (77°F). Do not freeze the ointment. Keep away from direct heat sources and sunlight.
- Container: Keep the aluminum tube tightly capped when not in use to prevent contamination and drying out of the ointment.
- Children: Store Bactroban out of the sight and reach of children. Accidental ingestion by children can cause gastrointestinal upset due to the macrogol base.
- Expiry date: Do not use Bactroban after the expiry date (marked "EXP" or "Use before") printed on the tube and outer carton. The expiry date refers to the last day of that month.
- Disposal: Do not dispose of Bactroban in wastewater or household waste. Return unused or expired medication to your pharmacy for proper disposal. This helps to protect the environment and reduce the potential for antibiotic resistance in the ecosystem.
Once opened, the ointment should be used within the period recommended by the manufacturer. If you notice any change in the color, consistency, or smell of the ointment, do not use it and consult your pharmacist. A change in these properties may indicate degradation of the active ingredient or contamination of the product.
What Does Bactroban Contain?
Understanding the composition of your medication helps you identify potential allergens and understand how the product works. Bactroban ointment has a relatively simple formulation consisting of one active ingredient and an ointment base.
Active Ingredient
Mupirocin 20 mg per gram of ointment (equivalent to 2% w/w). Mupirocin is a naturally derived antibiotic originally isolated from Pseudomonas fluorescens (NCIB 10586). It is chemically known as pseudomonic acid A and has the molecular formula C26H44O9. Mupirocin is a white to off-white crystalline solid that is freely soluble in acetone, chloroform, and dehydrated alcohol, and slightly soluble in water.
Inactive Ingredients (Excipients)
The ointment base consists of macrogols (also known as polyethylene glycols or PEGs). Specifically, the base is a blend of macrogol 400 and macrogol 3350. Macrogols serve as the vehicle for the active ingredient, providing a smooth, spreadable consistency that allows even application over the skin. They are water-soluble, which means the ointment can be easily washed off with water. Macrogols are generally well tolerated but can be absorbed through open or damaged skin, which is why caution is needed in patients with extensive wounds or renal impairment.
Packaging
Bactroban ointment is supplied in an aluminum tube with a screw cap containing 15 grams of ointment. The aluminum tube protects the ointment from light and air exposure, helping to maintain stability. The product should be stored according to the guidelines in the storage section above.
Frequently Asked Questions About Bactroban
Bactroban (mupirocin 2% ointment) is a topical antibiotic primarily used to treat impetigo, a contagious bacterial skin infection common in children. It is also effective against other superficial bacterial skin infections such as folliculitis, furunculosis, and secondarily infected wounds (minor cuts, abrasions, and insect bites). The active ingredient, mupirocin, is particularly effective against Staphylococcus aureus and Streptococcus pyogenes, the bacteria most commonly responsible for these infections. Mupirocin also retains activity against MRSA strains.
Most patients begin to see improvement in their skin infection within 3 to 5 days of starting Bactroban. The full treatment course is typically up to 10 days. It is important to continue using Bactroban for the entire prescribed duration, even if the infection looks better after a few days, to ensure all bacteria are eliminated and to reduce the risk of antibiotic resistance. If no improvement is seen after 5 days, contact your healthcare provider for reassessment.
Bactroban can be used on small, superficial wounds such as minor cuts, abrasions, and insect bites. However, it should not be applied to large areas of open or extensively damaged skin. The ointment base contains macrogols (polyethylene glycols), which can be absorbed through damaged skin and are excreted by the kidneys. In patients with kidney problems, this could lead to accumulation and potential toxicity. Always follow your healthcare provider's instructions regarding the extent of application.
Yes, mupirocin (the active ingredient in Bactroban) is effective against methicillin-resistant Staphylococcus aureus (MRSA). This is because mupirocin works through a completely different mechanism than beta-lactam antibiotics like methicillin. Mupirocin inhibits bacterial isoleucyl-tRNA synthetase, an enzyme essential for protein synthesis, while methicillin targets cell wall synthesis. Mupirocin nasal ointment is widely used in hospital settings for MRSA decolonization protocols. However, mupirocin resistance can develop with overuse, so it should always be used as prescribed.
Yes, Bactroban can be applied to bacterial skin infections on the face as directed by your healthcare provider. However, you must be very careful to avoid getting the ointment in your eyes, inside your nostrils, or in your mouth. If the ointment accidentally contacts the eyes, rinse thoroughly with clean water. Note that Bactroban skin ointment is a different formulation from Bactroban nasal ointment, and the two should not be used interchangeably. The skin formulation uses a macrogol base, while the nasal formulation uses a paraffin base designed specifically for mucosal application.
There is limited data on the use of Bactroban during pregnancy. Animal studies have not shown adverse fetal effects, but human data is insufficient. Bactroban should only be used during pregnancy if the benefit outweighs the potential risk. During breastfeeding, the minimal systemic absorption makes significant excretion in breast milk unlikely. However, if treating a cracked nipple, thoroughly wash off the ointment before nursing. Always consult your healthcare provider before using Bactroban during pregnancy or breastfeeding.
References
- 1 World Health Organization (WHO). WHO Model List of Essential Medicines - 23rd List. Geneva: WHO; 2023. Mupirocin listed as an essential topical antibiotic for skin infections.
- 2 European Medicines Agency (EMA). Summary of Product Characteristics: Mupirocin 2% Ointment. EMA; 2024. Official European prescribing information for mupirocin topical formulations.
- 3 U.S. Food and Drug Administration (FDA). Bactroban (Mupirocin) Ointment 2% - Prescribing Information. FDA; 2023. Full prescribing information including indications, dosage, contraindications, and adverse reactions.
- 4 British National Formulary (BNF). Mupirocin Monograph. NICE/BNF; 2024. Evidence-based prescribing guidance for mupirocin in UK clinical practice.
- 5 Cookson BD. The emergence of mupirocin resistance: a challenge to infection control and antibiotic prescribing practice. J Antimicrob Chemother. 1998;41(1):11-18. doi:10.1093/jac/41.1.11
- 6 Deshpande LM, Fix AM, Pfaller MA, Jones RN. Emerging elevated mupirocin resistance rates among staphylococcal isolates in the SENTRY Antimicrobial Surveillance Program (2000): correlations of results from disk diffusion, Etest, and reference dilution methods. Diagn Microbiol Infect Dis. 2002;42(4):283-290.
- 7 Oranje AP, Chosidow O, Sacchidanand S, et al. Topical retapamulin ointment, 1%, versus sodium fusidate ointment, 2%, for impetigo: a randomized, observer-blinded, non-inferiority study. Dermatology. 2007;215(4):331-340.
- 8 Williamson DA, Carter GP, Howden BP. Current and emerging topical antibacterials and antiseptics: agents, action, and resistance patterns. Clin Microbiol Rev. 2017;30(3):827-860. doi:10.1128/CMR.00112-16
- 9 Conly JM, Johnston BL. Mupirocin - are we in danger of losing it? Can J Infect Dis. 2002;13(3):157-159. doi:10.1155/2002/692715
- 10 National Institute for Health and Care Excellence (NICE). Impetigo: Antimicrobial Prescribing - NICE Guideline [NG153]. NICE; 2020. Evidence-based guideline recommending topical mupirocin as first-line treatment for localized non-bullous impetigo.
Editorial Team
This article has been written and reviewed by iMedic's medical editorial team, comprising licensed physicians with specialist qualifications in clinical pharmacology, dermatology, and infectious disease medicine.
iMedic Medical Editorial Team - Specialists in clinical pharmacology and dermatology with experience in evidence-based medical communication.
iMedic Medical Review Board - Independent panel of board-certified physicians who verify accuracy against current international guidelines (WHO, EMA, FDA, BNF, NICE).
All content on iMedic is based on Evidence Level 1A (systematic reviews and meta-analyses of randomized controlled trials) and follows the GRADE evidence framework. We have no commercial funding, no pharmaceutical sponsorships, and maintain full editorial independence. Content is reviewed at least annually or when new significant evidence becomes available. Read our full editorial standards.