Antibiotics and breastfeeding

[JSB16]

Hello,

I was put on a course of antibiotics earlier this week for strep throat, I am exclusively breastfeeding and was given penicillin.
My 5 month old has been projectile vomiting all morning after any milk, could be totally unrelated but I’m concerned it could be the antibiotics upsetting his stomach. Has anyone experienced this before while on antibiotics?

I have rung my Doctors for guidance and I’m on a call back queue.

Penicillin type antibiotics are normally pretty well tolerated, the gut side effects are usually at the other end because of temporary effects on natural gut bacteria. They aren't thought to cause toxicity via breastmilk. So it probably is a coincidence, obviously if your child is seemingly unwell and not tolerating feeds is reasonable to bring them to medical attention. One possibility is your illness was from a virus that the child now has, as things don't necessarily go the same way for every individual.