Teething is the process where an infant’s first set of teeth emerges through the gums, typically beginning around six months of age and continuing for the next couple of years. Parents commonly associate this milestone with physical symptoms, including increased drooling, fussiness, and gum discomfort. The presence of a runny nose is a frequently cited, yet often debated, symptom.
Separating Fact from Common Belief
The medical consensus is that a tooth pushing through the gum does not directly cause a runny nose or a fever. This common belief is based on the “coincidence theory.” Infants begin teething around six months, which is when they lose protective maternal antibodies, making them vulnerable to infections. Intense oral exploration to relieve gum pressure also increases exposure to germs and viruses, which are the true cause of nasal discharge. Additionally, the copious drool associated with teething can irritate the nasal passages, creating a watery discharge that mimics a cold.
Common Non-Teething Causes of Nasal Discharge
A runny nose (rhinorrhea) is overwhelmingly a symptom of a viral infection, specifically the common cold, which is caused by one of over 200 different viruses. Infants and toddlers often experience six to eight colds per year, especially in childcare settings. Mucus may start clear and watery to flush out the virus, but it often thickens and turns yellow or green as the immune system fights the infection. Respiratory Syncytial Virus (RSV) is another highly common viral infection that can lead to severe nasal congestion and discharge in young infants.
Environmental and Other Factors
Environmental factors frequently trigger nasal discharge. Dry indoor air, particularly when heating systems are running, can irritate the nasal lining, causing it to produce more mucus in an attempt to stay moist. Allergies to triggers like dust mites, pet dander, or pollen can also cause persistent symptoms, including sneezing and clear discharge. Less commonly, gastroesophageal reflux disease (GERD) may irritate the nasal passages. Furthermore, the narrow nature of an infant’s nasal passages means even a small amount of mucus can sound like significant congestion.
When a Runny Nose Requires Medical Attention
While most runny noses are caused by benign viral infections, certain accompanying symptoms require professional evaluation. A fever is a clear indicator that symptoms are caused by illness, not teething. Any fever of 100.4°F (38°C) or higher in an infant under three months old requires immediate medical attention.
Parents should also monitor for signs of breathing difficulty, such as wheezing, rapid breathing, or retractions where the skin visibly pulls in around the ribs or neck with each breath. These signs may indicate a more serious respiratory condition like bronchiolitis or pneumonia. Lethargy, unusual drowsiness, or extreme irritability are also red flags. Dehydration is a serious risk, so watch for fewer wet diapers, a dry mouth, or a lack of tears when crying. If a runny nose persists for more than 10 to 14 days, or if the mucus remains thick and discolored, a doctor should be consulted.