A live vaccine against tuberculosis (TB), also used in the bladder for bladder cancer
BCG vaccine
A live vaccine that protects against tuberculosis (TB), and is also placed into the bladder to treat certain bladder cancers.
What is BCG vaccine?
The BCG vaccine is a live vaccine that protects against tuberculosis (TB), an infection that mainly affects the lungs. It is given to people at higher risk of TB as part of UK health service guidance, usually as an injection into the skin. The same vaccine is also used in a completely different way: placed directly into the bladder as a treatment for some early bladder cancers. Because it contains a weakened but live organism, it must not be given to people who are significantly immunocompromised. A reaction at the injection site, sometimes forming a small sore that heals slowly, is normal. This is general information; follow the UK immunisation schedule and your specialist's advice.
Education and reference only. This is a plain-language guide to BCG vaccine — 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
The BCG vaccine is a live vaccine, meaning it contains a weakened form of a bacterium related to the one that causes tuberculosis. It is used mainly to protect people at higher risk of TB, a serious infection that usually affects the lungs, and is given according to UK health service guidance rather than routinely to everyone. The same vaccine has a second, separate use: it is put directly into the bladder to treat certain early bladder cancers, where it prompts the immune system to act against the cancer. It is a preventive vaccine in one role and a specialist cancer treatment in the other.
How it works
As a vaccine, BCG works by introducing a weakened, harmless form of the bacterium so the immune system learns to recognise and defend against TB, giving protection if the person later meets the real infection. When used in the bladder for bladder cancer, it is placed inside the bladder so that the immune system is stirred up locally, which helps the body attack and control cancer cells in the bladder lining. In both roles it relies on the immune system responding, which is exactly why it must not be given to people whose immune systems are seriously weakened.
Company & origin
Originated / developed by: Specialist manufacturers.
A live vaccine used in the UK to protect against tuberculosis (TB), and also given into the bladder as a treatment for some bladder cancers.
Practical use
How to take BCG vaccine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Have it given by a trained healthcare professional, as an injection into the skin for vaccination or into the bladder for bladder cancer.
- Tell the team beforehand if you, or the person being vaccinated, have a weakened immune system, as it must not be given then.
- Expect a reaction at the injection site that may form a small sore and heal slowly; keep it clean and avoid covering it tightly.
- If it is being used in the bladder, follow the specialist team's instructions before and after each treatment.
- Follow the UK immunisation schedule and your healthcare team's advice rather than self-deciding, as this is general information.
Weighing it up
Advantages & disadvantages of BCG vaccine
Advantages
- Helps protect people at higher risk against tuberculosis, a serious infection.
- Also offers an effective treatment, placed into the bladder, for some early bladder cancers.
- A long-established vaccine with decades of experience behind its use.
Disadvantages
- Must not be given to people who are significantly immunocompromised, because it is a live organism.
- The vaccination usually causes an injection-site sore that heals slowly and may leave a scar.
- When used in the bladder, it commonly causes temporary bladder symptoms after each treatment.
Practical use
Good to know
The most important safety point is that BCG contains a live organism, so it must not be given to people who are significantly immunocompromised, such as those with certain conditions or on treatments that seriously weaken the immune system, because the weakened bacterium could cause harm in them. When used as a vaccine, a reaction at the injection site is normal and expected: a small raised spot that may turn into a sore or ulcer and heals slowly over weeks, sometimes leaving a small scar. When used in the bladder for cancer, it commonly causes bladder symptoms such as needing to pass urine often or some discomfort for a short time after each treatment. This is general information only; national guidance sets out who should have the vaccine and when, and bladder treatment is given by a specialist team who will explain what to expect.
Who should not take it / use with caution
- People who are significantly immunocompromised must not be given it, because it contains a live organism that could cause harm.
- People who have had a serious allergic reaction to a previous dose should not be given it.
- It is avoided or delayed in pregnancy and in certain illnesses, and is given according to UK health service guidance and specialist advice.
Monitoring
- Checking the immune system is not significantly weakened before it is given.
- Watching the injection site heal and reviewing any glands that swell up.
- For bladder treatment, monitoring bladder symptoms and the response to each course under specialist care.
Side effects
- A reaction at the injection site, often a small sore or ulcer that heals slowly and may leave a scar; this is normal.
- Swollen glands near the injection site, or a mild high temperature, in some people.
- When used in the bladder, needing to pass urine often, discomfort or blood in the urine for a short time after treatment.
Key interactions
- Treatments that weaken the immune system make it unsafe, as it is a live vaccine.
- Other live vaccines may need to be spaced apart from it, on healthcare advice.
- Tell your team about all your medicines, especially any that affect the immune system.
Available as: A suspension given as an injection into the skin, or a preparation placed into the bladder.
Answers
BCG vaccine: frequently asked questions
What is the BCG vaccine for?
It is a live vaccine that protects against tuberculosis (TB), and the same vaccine is also placed into the bladder to treat some early bladder cancers.
Who can have it?
It is given to people at higher risk of TB according to UK health service guidance, but it must not be given to people who are significantly immunocompromised because it is a live vaccine.
Why does the injection site form a sore?
A small raised spot that may turn into a sore and heal slowly over weeks is a normal, expected reaction, and it sometimes leaves a small scar.
How does it treat bladder cancer?
Placed directly into the bladder, it stirs up the immune system locally to help the body attack and control cancer cells in the bladder lining.
Should I just arrange it myself?
No. This is general information; national guidance sets out who should have the vaccine and when, and bladder treatment is given by a specialist team.
The wider class
About Live vaccine (tuberculosis); bladder cancer treatment
BCG vaccine belongs to the live vaccine (tuberculosis); bladder cancer treatment 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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