Medication

Mupirocin

A prescription antibiotic ointment for a small patch of impetigo or an infected cut. It is deliberately kept for those jobs, because casual use is what makes it stop working.
Dr. Schwarz, MD · Board-certified dermatologistLast reviewed September 8, 2026
16:9 hero for Mupirocin. Never cropped: the tone strip and the corner logo depend on the full frame.

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Mupirocin is not a general antibiotic ointment. Its job is narrow: a small patch of impetigo, an infected crack or scratch, and clearing staph from the nostrils before certain operations. Resistance here is not theoretical — mupirocin is one of the few things that reliably clears staph from skin and noses, including many MRSA strains, and handing it out for every red spot is how a practice ends up with staph it no longer touches. For an ordinary clean cut, plain petroleum jelly under a dressing does the job, because what helps a wound heal is staying moist and covered.

— Dr. Schwarz, Board Certified Dermatologist

Key Facts

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Also calledBactroban, Centany, pseudomonic acid A
Drug classTopical antibiotic
Applied as2% ointment or cream for skin, and a separate 2% nasal ointment
Typical courseFive days, and rarely more than ten
Time to workClear improvement within three to five days
Prescription onlyYes in the United States

What It Is

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Mupirocin is a topical antibiotic from a soil bacterium, in use since the 1980s. Its jobs are impetigo, a crusted superficial infection most common in children, small infected cuts, cracks and bites, and clearing Staphylococcus aureus from the nose before surgery or in people who get repeated boils. It works against gram-positive bacteria, chiefly staph and strep. It does nothing for ringworm or athlete's foot, nothing for cold sores, and it is not an acne treatment. It is not the same as over-the-counter triple-antibiotic ointments, which combine bacitracin, neomycin and polymyxin. Those cover a different range and cause contact allergy far more often, mostly because of the neomycin.

How It Works

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Bacteria build proteins by adding amino acids in order, and each amino acid needs its own loading enzyme. Mupirocin blocks the one that loads isoleucine, so protein-building stops, the bacterium cannot grow, and at higher concentrations it dies. The human version of that enzyme is different enough that mupirocin leaves it alone.

It is chemically unrelated to any antibiotic given by mouth or drip, so bacteria that resist those are usually still killed by it. That is why its use is rationed. It is broken down quickly inside the body, so it only works on the surface.

Resistance comes in two forms. A mutation in the target enzyme gives low-level resistance, and a gene carried on a plasmid — a small loop of DNA bacteria pass to each other — gives high-level resistance. Both rise with use, and long or repeated courses drive them hardest. Hence the short course, and why this is not a general-purpose ointment.

Here is where Mupirocin acts in the skin, and what the others do instead.

About Mupirocin
Compare
Skin basics
BARRIEREPIDERMISDERMISPOREOILGLANDKILLS BACTERIAHARD TO GET INSTOPS PLUGS FORMINGUNCLOGS THE POREKILLS YEASTLOWERS OIL PRODUCTIONKILLS MITES

Mupirocin works on the bacteria growing in an inflamed pore. Less bacteria means less for the immune system to react to, which is what takes the redness and soreness out of a spot. For a real infection — impetigo, or a colonized crack in eczema. Not an acne treatment.

Mupirocin is a large molecule that barely crosses intact skin. That is deliberate: it stays where the infection is and almost none reaches the rest of the body.

Retinoids change how the lining of the pore sheds its cells, so the plug that starts a spot stops forming in the first place. That is why they prevent spots rather than treat the ones already there, and why the first weeks can look worse before they look better.

Salicylic acid dissolves in oil, so it gets down inside the pore rather than sitting on the surface, and loosens the plug of dead skin and sebum blocking the way out.

The yeast involved here lives on everyone's skin and only causes trouble when it overgrows in oil. This reduces it, which is why the flaking and itching settle and why it comes back if treatment stops for good.

This works upstream of the spot, on the gland itself. Less oil means fewer plugs, less for bacteria to feed on and less inflammation, which is why it changes the pattern rather than clearing one spot.

Everyone carries these mites in their follicles. In some people the immune system reacts to them, and reducing their number reduces the bumps and the redness that come with them.

The outer film of dead cells and oil. It holds water in and keeps irritants out, and it is thinner than a sheet of paper. Almost every dry, itchy, stinging skin problem starts here.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

What It Treats

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Impetigo
Impetigo
Strong evidence
The usual first choice for a small number of patches, applied three times a day for about five days after the crust has been softened off. For a few sores it works as well as tablets and avoids their side effects. It is also the ointment used inside the nostrils when impetigo keeps coming back and long-term carriage in the nose is the reason.
Folliculitis
Moderate evidence
An antibiotic ointment for a small, clearly bacterial patch, dabbed on the spots two or three times a day for about a week. It works well when the area is limited and the cause is genuinely bacteria. It does nothing for yeast folliculitis or razor bumps, and using it on and off for months is how resistance builds, so it is a short course rather than a standby.

Not the Best For

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Skin Tags
Skin Tags
Limited evidence
An antibiotic ointment for the small number of tags that get infected after being nicked or snagged — hot, swollen, oozing. It treats the infection on the surface and does nothing to the tag itself. If the redness is spreading into the surrounding skin, antibiotic tablets are needed instead.
Cellulitis
Cellulitis
Limited evidence
Useful only for the small crusted sore or infected wound that let the bacteria in, not for the cellulitis itself, which is far too deep for a cream to reach. Treating the entry point matters, but it happens alongside antibiotic tablets, never instead of them.
Sunburn
Sunburn
Limited evidence
An antibiotic ointment for the specific situation where broken blisters have become infected, which shows as increasing redness, swelling, heat or pus. It is not for a plain burn and does nothing for one. If the infection is spreading beyond the burnt area, antibiotic tablets are needed instead.
Dry Skin (Xerosis)
Dry Skin (Xerosis)
Limited evidence
An antibiotic ointment for a single cracked fingertip or heel that has become yellow-crusted and sore. It treats the infection sitting in the crack, not the dryness that opened it, so the cream and the ointment both continue. If redness is spreading up the limb, this is not enough and antibiotic tablets are needed instead.
Shingles
Limited evidence
An antibiotic ointment used only if the crusts turn hot, swollen or start oozing pus, which means bacteria have moved in on top. It does nothing to the shingles virus. If the infection is spreading, antibiotic tablets are needed instead.
Scabies
Scabies
Limited evidence
An antibiotic ointment for scratched areas that have become infected — golden-yellow crust, oozing, soreness rather than itch. It has no effect on the mites at all. If the infection covers more than a small patch, or the skin around it is spreading red and swollen, antibiotic tablets are needed instead.
Cellulitis and deeper infection
Doesn't work
An ointment reaches the surface only. Infection spreading into the deeper skin is treated from the inside.
An infection still there on day five
Doesn't work
It treats an infection rather than changing the skin, so the result shows in days. No improvement by day five is a reason to be seen again.
Staph carriage for good
Doesn't work
A five-day nasal course clears staph from the nostrils in most people, but carriage often returns over the following months.

Forms

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2% ointment:

2% cream:

2% nasal ointment:

Strengths

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One strength only.

The only strength
2%
Every mupirocin product is 2%. Nothing weaker to start on, nothing stronger to move up to. When 2% is not enough, the answer is an antibiotic by mouth.

Basics

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When to Apply
A thin layer three times a day on the patch only, after gently washing off loose crust with soap and water. A small dressing over the top is optional and limits spread to other people. Wash your hands before and after.
How to Start
Start the day it is prescribed and use it for five days; a course rarely runs past ten. The nasal ointment is a pea-sized amount in each nostril twice a day for five days, pinching the nose afterwards.
If It Irritates
Mild stinging in the first couple of days is common. Itching, redness spreading past the treated area, or new small blisters point to an allergy rather than a worsening infection — stop and ask.
If It’s Not Working
Impetigo should look clearly better by day three to five. If it is spreading, weeping more, painful, or you feel feverish, that needs an antibiotic by mouth rather than more ointment.

Sample Routine

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Here is where Mupirocin sits in a day, and what goes around it. Pick what you are treating and what your skin is like, and the rest of the routine changes to suit.

What to Expect

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First application | Using it
A thin layer on the affected skin. Some stinging is common.
Days 1 to 2 | Starting
Crusts soften. Little visible change yet.
Days 3 to 5 | Working
Redness fades, crusts lift, no new blisters. Impetigo should be clearly improving by now.
Days 5 to 10 | Finishing
The course ends and infected cuts and cracks are usually settled. Skin often stays slightly pink for a week or two afterwards.
5 days | Staph in the nostrils
A five-day nasal course clears carriage in most people.

What to Avoid

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  • Using it as a general first-aid ointment Most small cuts need no antibiotic. Petroleum jelly under a dressing keeps the wound moist, which is what helps healing.
  • Keeping a leftover tube for next time A day here and a day there from an old tube is how resistance builds.
  • Using it for longer than ten days A course that has not worked by day five will not work by day fifteen.
  • Burns, deep wounds or large raw areas This is for small superficial infections, and the base can be absorbed from extensive broken skin.
  • The skin ointment in the eyes or nose Keep it out of both. The nasal product is formulated differently.
  • Using it on fungal or viral problems Athlete's foot, ringworm and cold sores are not helped, and it can make a fungal rash look worse.
  • Sharing towels, flannels and bedding While impetigo is active it spreads easily by contact.

Monitoring

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No blood tests and no laboratory monitoring for ordinary use.

Monitoring is a look at the patch on day three to five. Clear improvement means finish the course. Spreading, pain, fever or swollen glands means review, and usually a tablet.

If infections keep coming back, a doctor may swab the skin and nostrils to check the bacterium is still sensitive to mupirocin. Repeated courses without that check produce resistant staph.

One group is watched more closely: people with significant kidney impairment treated over large open areas, because the polyethylene glycol base can be absorbed. Not an issue on a small patch.

If You Stop

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There is no taper and no rebound. You finish the course and stop. Stopping early, as soon as it merely looks better, is the common mistake. The infection can return, and partly treated bacteria are likelier to be resistant next time. Finish the days you were given. If infections keep coming back within weeks, ask where the bacteria live in between. The nostrils are the usual reservoir, which leads to swabs and a plan to clear carriage rather than another tube.

Cost

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Generic mupirocin 2% ointment is inexpensive in most countries and generally covered. The brand costs more and offers nothing extra. The nasal ointment causes the most trouble. It costs more, and plans sometimes decline it when it is used to prevent an infection rather than treat one. A small tube covers a patch of impetigo. Buying a large one to keep in the house is what leads to the leftover-tube problem.

Ask Your Doctor

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If you are pregnant or breastfeeding
Very little is absorbed through skin, but ask the doctor managing your pregnancy — and ask specifically before applying it near the nipple.
If the area is not clearly better
After five days, get it reviewed rather than keep going.
If you have a fever or feel unwell
Redness spreading outwards counts too. An infection beyond the patch usually needs a tablet.
If you have kidney disease
And a large raw area needs treating. The base can be absorbed from extensive broken skin.
If itching spreads past the treated edge
That suggests an allergy to the ointment rather than a worsening infection.
If you get boils again and again
Repeated skin infections count too. Ask about swabs and a plan to clear staph carriage.
If it is prescribed for your nose
Before an operation, use the full five days — the completed course is what lowers wound-infection risk.

How It Compares

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Fusidic acid cream
The same
Similar evidence in impetigo and widely used outside the United States, where it is not available. The resistance concern is the same and rises with use.
Triple-antibiotic ointment
Worse
The over-the-counter one has weaker evidence in impetigo, and the neomycin in it is a frequent cause of contact allergy. Cheap and available without a prescription, which is its main advantage.
Ozenoxacin cream
The same
A newer prescription option for impetigo with good trial results and a short two-day course. Considerably more expensive and less widely stocked.
Retapamulin ointment
Different job
Another prescription alternative with a different target and a five-day course. Availability and cost vary by country.
Antibiotics by mouth
Different job
The route when an infection is widespread, painful or accompanied by fever. Better reach, and body-wide side effects that a cream does not have.
Petroleum jelly and a dressing
Different job
Not an antibiotic and not a treatment for infection, but the right answer for an ordinary clean cut. It is worth naming because that is where most unnecessary mupirocin goes.
Mupirocin's case
Different job
It is the usual first choice for a small patch of impetigo. Its strength is that it works well on a small area, and its limit is that it should not be used for much else.

Myths

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  • "It is just a stronger Neosporin." Different drug, different target. The over-the-counter triple-antibiotic ointments contain neomycin, a common cause of contact allergy. Mupirocin is prescription-only because it is being conserved, not because it is heavier.
  • "Antibiotic ointment helps any cut heal faster." What helps a clean cut is staying moist and covered. Plain petroleum jelly does that.
  • "It works on MRSA, so it must be the strongest thing there is." It does treat many MRSA skin infections, which is exactly why it is reserved. Reserved is not strongest, and high-level resistance already exists.
  • "The skin ointment will do for inside the nose." The nasal product uses a different base, made for the lining of the nose.
  • "If it is not better, I should use more of it." Impetigo not improving by day five needs a different treatment, usually a tablet.

Questions Patients Ask

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Is mupirocin the same as Neosporin?

No. Neosporin combines bacitracin, neomycin and polymyxin over the counter. Mupirocin is a single prescription drug with a different target, and rarely causes contact allergy.

Why is it prescription only?

Partly because the infections need looking at, and partly to slow resistance. It is one of the few things that reliably clears staph, including many MRSA strains.

How long should I use it?

Five days for most skin infections, ten at most. Nasal courses are five days.

Can I use it on a burn or a large graze?

No. It is for small superficial infections. Large raw areas need proper wound care, and the base can be absorbed from them.

Will it help acne, a cold sore or athlete's foot?

No. It targets staph and strep. Cold sores are viral, athlete's foot is fungal, and an antibiotic ointment can make a fungal rash look worse.

Why does my doctor want me to put it in my nose before surgery?

The nostrils are where staph most often lives. A five-day course before some operations lowers the chance of it reaching the wound.

References

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