A beta-lactamase inhibitor given with a penicillin
Sulbactam
A protective partner medicine given with a penicillin antibiotic to help it work against resistant bacteria.
What is Sulbactam?
Sulbactam is a beta-lactamase inhibitor, a medicine that has little antibacterial effect of its own but is given together with a penicillin antibiotic, such as ampicillin, to help it work against bacteria that would otherwise resist it. It does this by blocking the enzyme that bacteria use to destroy penicillins. It is given as a combination injection. Because it is used with a penicillin, the cautions that matter most are penicillin allergy and the small risk of a gut infection called C. difficile, which apply to the combination as a whole.
Education and reference only. This is a plain-language guide to Sulbactam — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Sulbactam is a partner medicine known as a beta-lactamase inhibitor. On its own it does very little to kill bacteria, but it is given together with a penicillin antibiotic, most often ampicillin, and sometimes with a newer partner called durlobactam. Its role is to protect the penicillin so that it can work against bacteria that have learned to resist it. It is given as an injection, usually in hospital, as part of treatment for certain infections. Because it is always used in combination, its safety considerations are really those of the penicillin it is paired with.
How it works
Many bacteria defend themselves against penicillin antibiotics by making an enzyme called beta-lactamase, which breaks the antibiotic down before it can work. Sulbactam blocks this enzyme, acting like a shield so the penicillin survives and can attack the bacteria. By itself it has little antibacterial power, but in combination it restores the effectiveness of the penicillin against resistant bacteria. This is why it is never given alone but always paired with an antibiotic such as ampicillin, with the two working together.
Company & origin
Originated / developed by: Generic (long-established).
A medicine used in the UK and elsewhere alongside a penicillin antibiotic to overcome bacterial resistance, given as a combination injection.
Practical use
How to take Sulbactam
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as an injection, usually in hospital, combined with a penicillin antibiotic.
- Tell your team if you have ever had an allergic reaction to penicillins or other antibiotics before it is given.
- Report any rash, swelling or difficulty breathing straight away, as these can signal an allergic reaction.
- Tell your team about diarrhoea, especially if severe or with tummy pain, as this can occasionally signal a gut infection.
- Complete the full course your team prescribes, even if you feel better, to clear the infection properly.
Weighing it up
Advantages & disadvantages of Sulbactam
Advantages
- Restores the effectiveness of a penicillin against bacteria that would otherwise resist it.
- Helps treat infections caused by resistant bacteria when used in combination.
- A long-established partner medicine with well-understood use.
Disadvantages
- Has little antibacterial effect on its own and must be given with a penicillin.
- Carries the penicillin-allergy and C. difficile cautions of the combination it is part of.
- Given by injection rather than by mouth in usual use.
Practical use
Good to know
The key idea with sulbactam is that it is a helper rather than an antibiotic in its own right: it shields a penicillin from the enzyme that bacteria use to destroy it, so the two are always given together. Because the active antibiotic is a penicillin, the most important caution is penicillin allergy; anyone who has had a serious reaction to penicillins should usually not have the combination. As with any broad antibiotic, there is a risk of upsetting the natural balance of gut bacteria, which can occasionally lead to a gut infection called Clostridioides difficile (C. difficile) that causes diarrhoea and needs treatment. Diarrhoea, rashes and injection-site reactions can occur. Finishing the prescribed course matters to clear the infection and limit resistance.
Who should not take it / use with caution
- People who have had a serious allergic reaction to penicillins should usually not receive the combination.
- People who have had a serious allergic reaction to sulbactam itself.
- It is used with care in people with kidney problems, where the dose of the combination may need adjusting.
Monitoring
- Watching for allergic reactions, especially early in treatment.
- Reviewing how well the infection responds to the combination.
- Checking kidney function where relevant, as it can affect dosing.
Side effects
- Diarrhoea, nausea or stomach upset.
- Skin rash or itching, which can sometimes signal an allergy.
- Pain, redness or swelling where the injection is given.
- Rarely but seriously, a severe allergic reaction or a C. difficile gut infection, which need prompt treatment.
Key interactions
- Like penicillins, the combination can interact with the gout medicine probenecid, which raises antibiotic levels.
- It may affect how some other medicines work, so tell your team about everything you take.
- Tell your team about any other antibiotics or recent antibiotic courses.
Available as: A solution for injection, given combined with a penicillin antibiotic.
Answers
Sulbactam: frequently asked questions
What is sulbactam used for?
It is given together with a penicillin antibiotic, such as ampicillin, to help the penicillin work against bacteria that would otherwise resist it.
Does sulbactam kill bacteria itself?
It has very little antibacterial effect on its own; its job is to block the enzyme bacteria use to destroy penicillins, so the penicillin can do the work.
Can I have it if I am allergic to penicillin?
Usually not, because it is given with a penicillin; anyone who has had a serious penicillin reaction should tell their team before the combination is given.
What is the risk with diarrhoea?
As with any broad antibiotic, the combination can upset gut bacteria and occasionally cause a C. difficile infection; report severe or persistent diarrhoea to your team.
How is it given?
It is given as an injection, usually in hospital, combined with a penicillin antibiotic such as ampicillin.
The wider class
About Beta-lactamase inhibitor (used with a penicillin)
Sulbactam belongs to the beta-lactamase inhibitor (used with a penicillin) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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