Disseminated BCG reported, implies SCID or similar major immunodeficiency.

Severe BCG reaction can also indicate underlying TB infection!

More common issues are BCG abscess, and lymphadenitis.

Abscess at injection site appears after a few weeks, can persist for months. Treatment with isoniazid has been offered but no evidence of benefit. Incision probably makes things worse!

Non-suppurative lymphadenitis (not tender, no systemic symptoms) improves over a period of few weeks. Can progress to abscess however, with eventual spontaneous discharge and sinus formation. Healing then takes several months. Drug treatment does not appear to prevent abscess formation or speed up healing.

If an axillary abscess develops, needle aspiration can prevent perforation and sinus formation. Surgical excision might be needed if matted or multiloculated.