According to Baby Center, tooth buds form in the mouth before birth. The teeth begin to erupt, incisors first, around the fourth month of life on average. Every average has a high and a low, and babies as early as 3 months or as late as 6 months to a year begin to cut teeth. On rare occasions, babies will be born with teeth.
Teething is painful. Teeth are very sharp and they cut the gums to break through the surface. Babies as young as 3 months are used to having needs met immediately and pain relieved quickly. Teething pain is not a situation which can be remedied quickly. The infant has no idea why the pain continues and why no one is stopping the discomfort. The irritability is from the pain and frustration that no one can change the situation.
The tooth attempting to protrude from the gum will often cause the gum to swell. When a baby screams, a parent will notice an area of the gum is red and slightly larger than the surrounding area. This area is usually where the tooth is attempting to erupt. The parent will want to care for that area specifically when attempting to ease baby's discomfort.
Biting or Chewing
Biting soothes swollen gums and sometimes may help the tooth erupt. Babies love to chew on a cool cloth or a frozen teething toy designed for the purpose. The coolness numbs the gums, relieving pain. Stiff infant chewing toast is also available and works to satisfy the chewing desire. Be wary of foods such as carrots as they can chip and become a choking hazard.
Pain in the mouth may lead a 3-month-old baby to refuse food. The pain may be too much for the baby to handle and loss of appetite is a common side effect of pain. Babies love to eat normally; if a 3-month-old baby refuses food, immediately check for other signs of teething. If there are no other signs, a trip to the doctor's office should be seriously considered. A baby who refuses food at 3 months has a definite issue which should not be ignored.
Drooling and Chin Rashes
Teething produces an excess in infant saliva, and teething infants will drool excessively. If a 3-month-old baby seems to be drooling more than usual, there may be teeth erupting. Drooling may cause a rash on the chin, especially if the baby uses a pacifier. Wipe drool away gently without rubbing the skin. Apply petroleum jelly or lotion on the rash before nap and bedtime to help relieve the skin. Teething rashes are generally harmless if cared for properly.
Teeth don't keep a schedule. They will erupt day and night, and a baby who wakes up screaming suddenly in the night may be experiencing teething pain. If a 3-month-old baby who sleeps through the night suddenly begins waking up, he may be teething. Parents should look for other teething signs if a nighttime routine is violently interrupted by a cranky infant.
Diarrhea and Fever
Doctors disagree whether fevers and diarrhea accompany teething, but it is believed they are teething symptoms in some infants. The extra saliva drains into the stomach, causing diarrhea, and the eruption of the tooth through the gums may cause a low grade fever. According to Baby Center, if a 3-month-old infant has a fever higher than 100.5 degrees F, the parent should take the infant to a pediatrician to make sure the fever is teething related.
Symptoms such as a cough or a runny nose may be teething related, and it is the symptom which should be watched closest. Cold-like symptoms may be teething related as the erupting tooth may cause annoyances to the nasal passages, causing mucus to form. If a 3-month-old baby has cold-like symptoms, a parent should call a pediatrician to make sure the child's only issue is tooth related.