BCG Scar in Newborn: What Parents Need to Know

The BCG (Bacillus Calmette-Guérin) vaccine is given to protect against tuberculosis (TB) and is part of the routine immunization schedule in many countries. It is usually administered at birth or shortly after.

Here’s what parents should know about the BCG scar:

✅ What to Expect After BCG Vaccination

1. Local Reaction Timeline:

   • First few days: Small red bump may appear.

   • 2–4 weeks later: Bump turns into a blister or ulcer.

   • 6–12 weeks: It may ooze slightly and form a scab.

   • By 3–6 months: Heals to form a small, round scar.

2. Scar Size:

   • The final scar is usually 5–10 mm in diameter.

   • Not all babies develop a prominent scar — but the vaccine may still be effective.

❗ When to Worry

• Excessive swelling or pus: A little discharge is normal, but large amounts of pus or a persistent wound (>6 weeks) should be evaluated.

• Enlarged lymph nodes (especially under the arm) that are tender or growing.

• Fever or signs of infection unrelated to normal healing.

• No reaction at all after 3 months: Not usually a concern, but mention it during follow-up visits.

💡 Parent Tips

• Don’t apply creams or ointments on the BCG site.

• Avoid bandaging unless instructed by a doctor.

• Let the area stay dry and clean.

• Do not try to pop or drain the blister.

✅ Why the Scar is Good

• A visible BCG scar often indicates the body has responded to the vaccine.

• The presence or absence of a scar doesn’t guarantee immunity, but is usually a normal part of the process.