Why Is My Baby Bottle Leaking? Causes and Fixes
By Dr Browns | Published: 2026-10-16
Category: Tips & Care
Stop baby bottle leaking for good. Learn the common causes, from collar tightness to teat seals, and when to replace parts instead of troubleshooting.
Quick answer
Most baby bottle leaking happens at the collar because it is too loose, too tight, or the teat is worn. Check that the collar is snug but not forced, the teat sits flat, and the vent is clear. If the leak continues, replace the teat or collar rather than adding tape or extra tightening.
Check the collar first
The collar is the most common leak point. A collar that is too loose lets milk escape between the teat and bottle neck. A collar that is overtightened can distort the teat base and create a gap. Tighten until you feel firm resistance, then stop. If the collar has a cracked thread or a warped rim, no amount of tightening will seal it.
Inspect the teat seal and vent
The teat base must sit flat against the bottle neck. If it is folded, pinched, or twisted, milk will find a path out. Remove the teat, check for small tears or sticky residue, and reseat it. For vented bottles, a blocked vent can force milk up through the collar. Clean the vent holes with a small brush and rinse thoroughly.
Match the teat flow to your baby
A teat that is too fast for your baby can cause milk to pool around the collar and leak. Premature and breastfed newborns often need the slowest flow available. If your baby is gulping, coughing, or letting milk run out the sides of the mouth, try a slower teat before assuming the bottle itself is faulty.
Watch for travel and storage leaks
Leaks in a diaper bag usually come from a missing travel cap or a loose collar during transport. A travel cap seals the teat for carrying, but it is not a substitute for a properly tightened collar. If you use a straw cup, check that the straw and lid are fully seated; a worn straw can leak at the lid joint.
Leak diagnosis: symptom, cause, action
- Milk pools around the collar: The collar is likely too loose or the teat base is not seated flat. Tighten until firm, then check the teat for folds or residue. If it still leaks after reseating, replace the teat.
- Milk drips from the teat tip between feeds: A worn or split teat tip cannot seal. Inspect the tip by squeezing it gently; if it stays open or looks torn, it is done. Replace the teat. Do not try to repair it.
- Leaks only when traveling: A missing travel cap or a collar that loosened in the bag is the usual cause. Use a travel cap and check the collar before packing. If the cap is cracked or missing, replace it.
- Leaks continue after new teat and collar: The bottle body may have a hairline crack or a warped neck. Hold it up to light and look for cracks near the threads. Replace the bottle. Continued leaks are not normal.
Parts that solve common leaks
- Dr Brown's Options+ Wide Neck Preemie Teats: Dr. Brown’s Natural Flow Options+ Preemie Flow Wide-Neck Nipple is the slowest-flow teat, designed for premature and breastfed newborns. If your baby leaks milk because the flow is too fast, this teat can reduce pooling at the collar and make feeding more comfortable.
- Dr Brown's Options+ Narrow Neck Starter Kit: The Dr Brown's Options+ Narrow Neck Starter Kit includes 4 oz and 8 oz bottles with Level 1 and Level 2 teats, plus an internal vent system that channels air away from the feed. A complete set lets you match teat levels to your baby and replace worn parts, which helps prevent leaks caused by mismatched or aging components.
