Can both active ingredients in co-amoxiclav pass into breast milk?

Yes, both active ingredients in co-amoxiclav—amoxicillin and clavulanic acid—pass into breast milk; clavulanic acid’s effects on the infant are unknown, diarrhoea, mucosal fungal infection and sensitisation are possible, breastfeeding may need to stop, and use requires the treating physician’s benefit–risk assessment.