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BCG (TB) vaccine side effects

Like all vaccines, the BCG vaccine can cause side effects, but they're uncommon and generally mild.

Side effects may include:

  • soreness or discharge where the injection was given
  • high temperature (fever)
  • headache
  • swollen glands under the armpit in the arm where the injection was given

Most people develop a sore at the injection site. Once healed, the sore may leave a small scar. This is normal and nothing to worry about.

More serious complications, such as abscesses, bone inflammation and widespread TB are rare.

BCG vaccination scar

Almost everyone when given the BCG vaccination will develop a raised bubble at the site of the injection, which may disappear soon afterwards.

About 2 to 6 weeks after the injection, a small spot may appear at the site of the injection.

It's normal for the spot to turn into a blister, which sometimes oozes before becoming a crusty scab.

It's important to leave the area uncovered as the air will help it to heal. It's normal for it to leave a small scar.

Occasionally, there may be a more severe skin reaction, but this should heal within several weeks.

If you're worried that your or your child's skin reaction is abnormal or that the spot may have become infected, contact a GP.

Allergy to the BCG vaccine

Serious side effects from the BCG vaccine, such as a serious allergic reaction (anaphylactic reaction), are very rare.

All staff who give vaccinations are trained to treat allergic reactions.

Anyone who has an allergic reaction to a vaccine recovers completely with no lasting effects if they're treated promptly.

The Yellow Card Scheme allows you to report suspected side effects from a vaccine. It's run by the medicines safety watchdog the Medicines and Healthcare projects Regulatory Agency (MHRA).

Find out more about the BCG vaccine

Page last reviewed: 23 April 2019
Next review due: 23 April 2022