Most lip blisters in newborns are caused by all the sucking they’re doing to get their milk. They’re often caused by friction on their sensitive lips. The skin of the lip had 3-5 cellular layers, very thin compared to typical face skin, which has up to 16 layers. The lip skin is doesn’t have sweat glands, so it lacks the protective layer of sweat and body oils which keep the skin smooth and moist. This makes the lips dry out faster and become easily chapped.
Lip blisters, AKA:
- Friction blisters
- Suck blisters
- Suck callouses
The sucking reflex starts around week 32 in the womb and is fully developed around 36 weeks. Occasionally a baby may be born with these blisters if they were super active at sucking in the womb.
Babies should latch by cupping their tongue around the breast and creating a vacuum seal in their mouth. The tongue then pumps up to compress the breast to squeeze out milk and then pumps down to generate negative pressure in the mouth to draw milk in like a syringe. The tongue is the dominant organ in effective breastfeeding. The lips actually play a passive role in feeding and should stay soft without the muscles engaged. They are only meant to prevent milk from leaking out of the mouth. Babies get suck blisters/two tone lips from overusing their lip muscles, specifically the one that rounds and closes the lips, called the orbicularis oris.
Think of it like this: try drinking from a straw. You usually put the straw in about 1-2 inches so your tongue and teeth help support it. This gives the straw stability so you can direct the flow of liquid in your mouth. If the straw is only touching the border of your lips, you need to use more of your lip muscles to keep the straw in place and from falling out of your mouth. Your tongue, cheeks, and teeth/gums provide needed support to keep the straw in without over working your lips. Same with the breast or a bottle nipple. The baby’s tongue is supposed to be the dominant muscle in maintaining the latch, with the cheeks and lips playing a passive, supportive role.
Very small blisters that go away in a few days are normal for newborns as they’re learning to latch and suck. Blisters that don’t disappear in the first week or two or that are extensive across the lips are a sign something is going on.
Reasons for lip blisters:
👄 Baby’s in a shallow latch (to breast or bottle) use their lips to hold on to prevent losing the latch. This is the simplest to fix. Fix the latch, the blisters go away. Usually baby is in a shallow latch because of how they’re positioned. Make sure baby is completely touching your body, tummy time tummy with their belly button touching you and not on their back. Baby’s face should be coming straight to your breast instead of turned toward one shoulder.
👄 Lip blisters are a classic sign of tongue/lip tie where the lips are compensating for the lack of range of motion/strength/coordination of the tongue because it’s being tethered to the floor of the mouth.
👄 Premature babies may also get lip blisters as they should still be practicing swallowing in the womb with no expectations. Babies born 34.0-38.6 weeks gestation may look like fully formed babies, but have a lot of maturing and growth to do outside the womb. Their brains would rather be sleeping than eating, and they can fatigue quickly at the breast. They also use those later weeks in utero to practice sucking and swallowing while being fed through the umbilical cord. Premies Also have under developer fat pads in their cheeks. The last weeks of pregnancy help fattening these up. The fat pads support the tongue to make sucking more efficient while decreasing the amount of space in the mouth, this means less suction is needed to draw milk into their mouth. Without the fat pads, babies use alternative muscles to maintain a latch, hence the lip blisters as they’re using their lips more than needed.
👄 When babies are born, there is a lot of pressure on their head and neck. Babies are also supposed to move their head and body around in the womb and again during delivery to help themselves be born. Sometimes they get stuck in a certain position and this can put extra pressure on the baby’s body. If they sat low in pregnancy, we’re always positioned in a certain way, or have little room to move around, we can some times see cranial nerve dysfunction. This can also happen when a baby is pulled out (cesarean, vacuum, forceps). Proper nerve function allows correct muscle movement. If a nerve involved in sucking is temporarily squished, pinched, or strained, certain muscles (tongue, cheeks) can’t function properly which can lead to compensations. See the videos on my YouTube channel for stretches to help baby move their muscles better. If you think baby may have a stretched nerve, chiropractic care, craniosacral therapy, physical or occupational therapy can definitely help.