My Baby Breathes Through Their Mouth
The short answer
Young babies are preferential nose breathers and typically only breathe through their mouths when crying. If your baby is consistently mouth breathing, it is usually due to nasal congestion from a cold or allergies. However, chronic mouth breathing in an infant or toddler, especially during sleep, can sometimes indicate enlarged adenoids, nasal obstruction, or other issues that warrant evaluation.
This is one of the most common questions parents ask. Searching for answers means you care.
By Age
What to expect by age
0-3 months
Newborns are obligate nose breathers for the first few months, meaning they strongly prefer to breathe through their nose. Nasal congestion from dried mucus, a cold, or narrow nasal passages can cause noisy breathing and may lead to mouth breathing. This can interfere with feeding since babies need to breathe through their nose while nursing or bottle-feeding. Saline drops and gentle suctioning can help. Persistent mouth breathing in a newborn, especially with feeding difficulty, should be evaluated to rule out choanal atresia (a blockage of the nasal passages) or other anatomical issues.
3-12 months
As babies grow, they develop the ability to switch between nose and mouth breathing more easily. Temporary mouth breathing during a cold is normal and expected. If your baby is chronically mouth breathing even when not sick, observe whether it occurs primarily during sleep (suggesting enlarged adenoids or tonsils) or all day. Persistent nasal congestion with clear drainage may indicate environmental allergies, though true allergies are uncommon before 12 months.
1-3 years
Chronic mouth breathing in toddlers is most commonly caused by enlarged adenoids, allergic rhinitis, or chronic congestion. Signs of adenoid enlargement include habitual mouth breathing, snoring, restless sleep, and sometimes a nasal quality to the voice. Adenoid tissue grows through early childhood and is largest around age 3-7. If your toddler snores regularly, sleeps with their mouth open, and seems to have pauses in breathing during sleep, your pediatrician may refer you to an ENT specialist for evaluation.
What Should You Do?
When to take action
- Temporary mouth breathing during a cold or when the nose is stuffy, which resolves as congestion clears
- Mouth breathing during crying, which is a normal response
- Brief mouth opening during deep sleep that is not habitual
- Your baby switches between nose and mouth breathing naturally and feeds without difficulty
- Your baby or toddler seems to breathe through their mouth most of the time, even when not sick
- Your child consistently snores, sleeps with their mouth open, or has restless sleep with frequent position changes
- You notice your child frequently has a dry mouth, cracked lips, or bad breath from chronic mouth breathing
- Your newborn cannot breathe through their nose at all and struggles to feed, as this could indicate a structural nasal obstruction requiring urgent ENT evaluation
- Your child has mouth breathing with observed pauses in breathing during sleep (sleep apnea), gasping or choking awake, excessive daytime sleepiness, or behavioral issues from poor sleep quality
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
Worrying about your baby means you care. That is a good thing.
Related Medical Concerns
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.
Adenoid Hypertrophy and Breathing
Adenoids are lymphoid tissue located behind the nose that help fight infection in young children. When adenoids become enlarged (adenoid hypertrophy), they can block the nasal airway, causing chronic mouth breathing, snoring, nasal speech, and sleep-disordered breathing. Enlarged adenoids are most common between ages 2-7 and are a leading cause of obstructive sleep apnea in young children. Treatment ranges from watchful waiting and nasal steroids to surgical removal (adenoidectomy) if breathing or sleep is significantly affected.
How to Advocate for Your Child's Needs
You know your child better than anyone, and your observations matter. If you feel something is not right with your child's development or health, you have every right to ask questions, request evaluations, and seek second opinions. Advocating for your child is not being difficult - it is being a good parent.
Air Quality and Baby Health
Babies and young children are more vulnerable to air pollution than adults because they breathe faster, their lungs are still developing, and they spend more time close to the ground where some pollutants concentrate. The EPA recommends keeping babies indoors when the Air Quality Index (AQI) exceeds 100 (orange level). During wildfire smoke events, keep windows closed, use air purifiers with HEPA filters, and monitor your child for coughing, wheezing, or difficulty breathing. Long-term exposure to air pollution can affect lung development.
Altitude Sickness in Babies
Babies and toddlers can experience altitude sickness when traveling above 5,000-8,000 feet (1,500-2,500 meters). Symptoms are harder to recognize in infants because they cannot describe how they feel. Watch for unusual fussiness, poor feeding, disrupted sleep, vomiting, and fast breathing. Gradual ascent is the best prevention. Most pediatricians recommend avoiding sleeping at very high altitudes (above 8,000 feet) with infants when possible, and descending immediately if symptoms appear.