When your baby latches onto one breast, the other one often starts leaking. This is completely normal, and you have several options: catch the milk, stop the flow with gentle pressure, or simply absorb it with a nursing pad. What works best depends on whether you want to save that milk, how much you’re leaking, and whether oversupply is a concern.
Why the Other Breast Leaks
When your baby suckles, your brain releases oxytocin, a hormone that triggers tiny muscles around your milk-producing glands to squeeze milk into the ducts. This happens in both breasts at the same time, not just the one your baby is feeding from. Your body can even start this reflex before a feed begins, just from anticipating it. The leaking you notice on the opposite side is simply milk being pushed out with nowhere to go.
Leaking tends to be heaviest in the early weeks and months, when your body is still calibrating how much milk to produce. It often tapers off over time as supply regulates, but some parents leak throughout their entire breastfeeding journey.
Apply Gentle Pressure to Stop the Flow
If you’re out in public or just don’t want to deal with leaking, you can stop it with a simple hands-on technique. Hold your nipple between your index and middle fingers, or press the heel of your hand gently into the side of your breast when you feel the let-down start. This counter-pressure is enough to slow or stop the flow temporarily without affecting your supply. Crossing your arms and pressing both forearms against your chest works too, and looks more natural in social situations.
Use a Nursing Pad to Absorb It
The simplest approach is to tuck a nursing pad into your bra on the non-nursing side and let it catch whatever comes out. This is the lowest-effort option, and it avoids any extra breast stimulation that could increase your milk production.
Reusable pads made from cotton or bamboo-viscose blends are more economical and breathable than disposable ones. Research on nursing pad materials has found that soybean fibers blended with cotton offer particularly strong absorbency, liquid retention, and antimicrobial properties. Disposable pads tend to be thinner and more discreet under clothing, so it comes down to personal preference. Whichever type you choose, swap them out when damp to keep skin healthy and prevent irritation.
Catch the Milk With a Collector
If you’d rather save that leaking milk instead of absorbing it, you have two main tools.
Silicone Suction Collectors
Products like the Haakaa attach to your breast with suction and collect milk during a feed. They’re popular because they can gather a surprising amount of milk without any effort. But there are trade-offs worth knowing about. La Leche League Canada notes that these collectors often get in the way and can lead to poor positioning and latch. They’re easily knocked off by you or your baby. More importantly, the suction actively draws milk out, which can remove more than what would naturally leak. Over time, this extra removal signals your body to produce more milk, potentially creating an oversupply problem.
If you want to use one without the suction effect, you can hold it under your breast without squeezing it on, letting it passively catch drips. This is awkward to manage one-handed while nursing, though.
Milk Collection Shells
These are small disc-shaped containers that sit inside your bra with a hole positioned around the nipple. They passively catch milk that leaks out on its own, without adding suction. They’re more hands-free than a silicone collector, but if your bra fits tightly, the shell can press on your areola and actually cause more milk to flow. If too much milk collects from this breast, your baby may get frustrated when switching sides and finding less milk available.
For most parents who just want to save small amounts of let-down milk, shells are a reasonable low-effort option.
Storing Collected Milk Safely
Any milk you catch from the non-nursing breast follows the same storage rules as pumped milk. Wash your hands before handling it, and transfer it into a clean, capped glass or BPA-free plastic container, or a storage bag designed for breast milk. Label it with the date.
Freshly expressed milk stays safe at room temperature for up to six hours, though using or refrigerating it within four hours is better, especially in warm rooms. In the back of the refrigerator, it keeps for up to four days. In a deep freezer, it lasts up to 12 months, but using it within six months is ideal. Once thawed, use it within 24 hours and don’t refreeze it.
When Oversupply Is a Concern
If your breasts feel painfully full between feeds, you’re soaking through pads constantly, or your baby chokes and sputters during let-down, you may be dealing with oversupply. In this case, what you do with the other breast matters more than convenience.
The current medical thinking on oversupply has shifted significantly. Providers used to recommend emptying the breasts more often to relieve engorgement. Research now shows this makes the problem worse by signaling your body to ramp up production even further. A good rule of thumb: only remove what your baby needs. Don’t pump the other breast “just to relieve pressure,” and avoid using suction collectors that draw out extra milk.
One strategy that can help is block feeding. You nurse from only one breast for a set block of time, often around three hours, then switch to the other breast for the next block. By reducing how often each breast is stimulated, your overall production gradually decreases. Some parents notice improvement in as little as 36 hours. The specific block length varies, so it’s worth discussing timing with a lactation consultant.
Avoiding Engorgement and Blocked Ducts
If your baby strongly prefers one side or you tend to skip the second breast, the unused side can become engorged. Engorgement means the breast is overly full, swollen, and warm to the touch, and it’s one of the most common paths to mastitis (painful breast inflammation). This is most likely in the early days after birth but can happen anytime you’re producing milk.
To keep things balanced, alternate which breast you start with at each feeding. If one breast feels uncomfortably full, nurse from that side first or express just enough milk by hand to relieve the pressure, not to fully drain it. Avoid tight-fitting bras and breast shells that press on your tissue, as both can contribute to blocked ducts. The goal is to keep milk moving without telling your body to make more of it.