Caffeine is safe to take while breastfeeding in moderation (up to 300mg per day). Only about 1.5% actually enters breast milk. Caffeine enters your bloodstream about 15 minutes. It peaks in your blood within 60 minutes and has a half-life of 3-5 hours. The half-life is the time it takes for your body to eliminate half of the drug. The remaining caffeine can stay in your body for a long time. The half-life of caffeine is about 97.5 hours in a newborn, 14 hours in a 3-5 month old baby and 3-5 hours in a baby older than 6 months. Because caffeine takes much longer to clear out of a young baby’s system it is possible that high caffeine intake can make a baby irritable. If baby is sensitive to the caffeine now, they may not be when they’re older. Cut caffeine now and try again in a few months.
So if you drink a cup of coffee with 100mg of caffeine at 7am, you’ll have 50mg of caffeine in your bloodstream at 10am. Your baby would get 1.5mg of caffeine.
Every baby is different in how they react to caffeine. If you drank coffee while pregnant, your baby had an IV of caffeine (called the umbilical cord) and is already used to having it in their blood stream. If you didn’t drink coffee or switched to decaf, your baby may have a more noticeable reaction when you drink coffee. When drinking coffee after birth, go low and slow. There’s nothing you can do to decrease caffeine in your system except time. Start with a very small cup first thing in the morning and see how your baby reacts. Drinking your morning cup of coffee while your breastfeeding gives you the most time for the caffeine to peak and start decreasing before your next feeding.