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Attenuated Tubercle Bacillus

Why is it prescribed?

This injection is indicated for the prevention of tuberculosis in people who are at a high risk of exposure and who are not already infected by the tubercle bacillus as indicated by a negative Mantoux test.

Products that have this ingredient include •BCG vaccine •

See other drugs used in the treatment of •tuberculosis •

Generally, vaccination with attenuated tubercle bacillus is well tolerated. The frequency and severity of unwanted effects depend on the dosage and method of administration, the age of the person receiving the vaccine, and the substrain of the bacillus used by the manufacturer. Unwanted effects are usually mild and infrequent but can be severe and sometimes occur a year or more following administration of the vaccine. Possible unwanted effects include:

  • a small, hardened, blister-like formation at the injection site
  • ulceration (inflamed open lesion at the injection site)


  • enlargement of lymph nodes (may last for several months)


  • life threatening allergic reaction

Attenuated tubercle bacillus vaccine is manufactured using live bacteria that are very similar to the disease-causing tubercle bacillus. These bacteria have undergone an attenuation process that reduces the bacteria's ability to cause disease. The final product is a vaccine that is injected into the body of people at risk of being infected with tuberculosis (TB). The bacteria used in the vaccine are so similar to the disease-causing tuberculosis bacteria, that it simulates a natural infection with the disease causing tuberculosis bacteria and promotes immunity against TB.
Before anyone is vaccinated, they must test negative to the Mantoux (Tuberculin PPD) test. The test involves injecting inactive material from the TB organism just under the skin. People previously exposed to TB infection will develop a local skin reaction 2 to 3 days after the skin test is given.
To confirm that immunity against tuberculosis has developed following vaccination, a Mantoux test is preformed. A positive Mantoux result indicates that immunity has developed against the TB causing bacteria. After vaccination, it may require up to 3 months before a positive Mantoux result can be seen.

Administration of BCG vaccine should be postponed in persons with severe acute illness. Persons with minor or moderate acute illness (with or without fever) may be vaccinated.

Immunity can not be determined until a positive Mantoux result is seen. A vaccinated person may be susceptible to TB before sensitivity has been confirmed. Vaccinated people should avoid contact with all known or suspected persons that have been infected with the tubercle bacillus until sensitivity to tuberculin is verified (usually within 3 months).
Drug Interactions: It is important to tell your doctor and pharmacist of any prescription or over-the-counter medications you are taking. In some cases, the dose of one or both drugs may need to be altered or another drug may be prescribed. The following drugs or drug classes have been known to interact with vaccine:

  • immunosuppressive agents (e.g. corticosteroids)
  • antituberculosis drugs (e.g. isoniazid, rifampin)

Use is not recommended in the following situations:

  • allergy to any component of the vaccine
  • fever or other signs of acute infection
  • extensive skin disease or burns
  • positive tuberculin test (Mantoux)
  • suppressed immune system (e.g. HIV)

Use in pregnancy: This vaccine is not recommended during pregnancy unless there is an excessive or unavoidable exposure to infective TB. Vaccination of pregnant women is usually delayed until after delivery, although no harmful effects on the fetus have been observed. Consult your doctor or pharmacist if you suspect you are pregnant.
Use in breastfeeding: It is not known whether this vaccine is excreted in human milk. Because live vaccines may be excreted in human milk, caution should be exercised when administered to a nursing woman. Consult your doctor or pharmacist if you are breastfeeding.