Viral colds typically last 7 to 10 days, but if symptoms persist, it is best to see a doctor to rule out secondary infections. Your current cold medication contains ingredients that can reduce breast milk supply and cause drowsiness in your baby, so it is safer to avoid it. For pain or fever, paracetamol is a safer choice while breastfeeding. Never give over-the-counter cold medications to an 11-month-old. Instead, safely relieve her congestion using saline nasal drops, a cool-mist humidifier, and ensuring she stays well-hydrated. Please consult her pediatrician for an appropriate evaluation.