VaccinationsBCG (TB) vaccine side effects

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Reactions to the BCG vaccine are common, but serious long-term complications are rare. Most children develop a sore at the injection site. Once healed, the sore may leave a small scar. This is normal and nothing to worry about.

BCG vaccination scar

Virtually 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 is normal for the spot to turn into a blister, which sometimes produces discharge before becoming crusty where the fluid has dried on the surface.

It is important to leave the area uncovered as the air will help it to heal and it is 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 are worried that you or your child's skin reaction is abnormal or that the spot may have become infected, contact your GP.

Allergy to the BCG vaccine

Serious side effects to the BCG vaccine, such as an anaphylactic reaction (a serious allergic reaction), are very rare. They occur in less than 1 in a million cases.

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.

To find out more, read Vaccine safety and side effects.

Find out how to report a vaccine side effect.

Read more about the BCG vaccine.

Page last reviewed: 13/03/2016
Next review due: 13/03/2019