Teething hurts because a baby’s teeth literally have to break through bone and gum tissue to reach the surface. This isn’t a gentle process. The body has to dissolve bone, push a hard tooth edge through soft, nerve-rich tissue, and manage the inflammation that follows. Each tooth eruption can cause discomfort lasting 3 to 8 days, with symptoms peaking right as the tooth breaks through.
What Happens Inside the Gums
Baby teeth start forming in the jaw long before birth, but they begin pushing toward the surface around 6 months of age. For a tooth to erupt, the body first has to clear a path through the bone of the jaw. It does this by sending specialized cells to the area that break down and absorb bone tissue, creating a channel for the tooth to move through. This bone resorption is an active, inflammatory process, not a passive one.
As part of this process, cells in the tissue surrounding the developing tooth release signaling molecules that trigger inflammation. These molecules recruit immune cells to the area, which in turn produce additional inflammatory signals, including prostaglandins. Prostaglandins are the same chemicals responsible for swelling and pain sensitivity elsewhere in the body. The result is a cascade: the closer a tooth gets to the surface, the more inflammation builds up in the surrounding gum tissue. By the time the sharp edge of the tooth is pressing against the final layer of gum, that tissue is already swollen, tender, and packed with inflammatory chemicals.
Why It Registers as Pain
The gums are supplied by branches of the trigeminal nerve, which is the largest sensory nerve in the head. This nerve has three main branches. The upper jaw teeth connect to the maxillary branch, which also serves the sinuses, nasal cavity, and mid-face. The lower jaw teeth connect to the mandibular branch, which covers the lower cheeks, tongue, and floor of the mouth. These nerve fibers carry pain, touch, and temperature signals directly to the brain.
When a tooth pushes through inflamed gum tissue, those nerve endings fire constantly. The inflammatory chemicals in the area also lower the threshold at which nerves send pain signals, meaning even light pressure (from feeding, a pacifier, or the baby’s own tongue) can register as painful. This is the same mechanism that makes a paper cut sting far more than you’d expect from such a small wound. The tissue around an erupting tooth is essentially in a state of low-grade injury, and the nervous system treats it accordingly.
Because the trigeminal nerve branches serve such a wide area of the face, teething pain can radiate. A baby cutting a lower molar might tug at their ear or rub their cheek, not because anything is wrong with those areas, but because the nerve signals overlap.
How Long Each Tooth Hurts
Teething pain typically starts a few days before the tooth breaks through the gum surface and continues for a few days after. Each episode lasts roughly 3 to 8 days. The worst discomfort tends to land on the day the tooth actually erupts. Since babies have 20 primary teeth that come in over roughly two years, teething isn’t one continuous stretch of misery. It’s a series of relatively short episodes separated by pain-free gaps.
The first teeth usually appear around 6 months, starting with the lower front teeth. Not all teeth seem to cause equal discomfort. The broad, flat molars, which have a larger surface area pushing through the gum, tend to be more painful than the narrow front teeth. Some babies sail through certain eruptions with barely a fuss and struggle noticeably with others.
The Fever Question
Many parents notice their baby feels warm during teething, and the data supports a small temperature increase. In a clinical study tracking daily temperatures, babies averaged about 36.9 to 37.1°C (98.4 to 98.8°F) in the weeks before a tooth erupted. In the three days leading up to eruption, temperatures rose slightly, peaking at an average of 37.6°C (99.7°F) on the day the tooth came through.
That’s a measurable increase, but it falls below the standard medical definition of a fever, which starts at 38°C (100.4°F). Some individual babies in the study did cross that threshold, but the average did not. If your baby has a temperature above 38.5°C (101.3°F), something other than teething is likely going on, and it’s worth investigating rather than assuming it’s just a new tooth.
What Actually Helps With the Pain
The most effective non-medication approach is simple counterpressure. A clean, chilled (not frozen) teething ring or a cold, wet washcloth gives the baby something firm to bite down on, which pushes back against the pressure of the erupting tooth and can temporarily override pain signals. Gently rubbing the gums with a clean finger works the same way. The cold adds mild numbing and helps reduce swelling in the tissue.
For pain that interferes with feeding or sleep, acetaminophen is an option for babies, dosed by weight using an oral syringe for accuracy. The standard pediatric liquid concentration is 160 mg per 5 mL, and it can be given every 4 hours as needed, up to 5 doses in 24 hours. For babies under 2, a pediatrician should confirm the appropriate dose. Ibuprofen is another option but only for babies 6 months and older.
Products to Avoid
Numbing gels and liquids containing benzocaine (sold under names like Orajel, Anbesol, and others) should not be used on teething babies. The FDA has warned that benzocaine can cause a condition called methemoglobinemia, in which red blood cells lose their ability to carry oxygen effectively. This is rare but potentially fatal. Prescription lidocaine solutions carry similar risks, including seizures, heart problems, and severe brain injury when too much is swallowed or absorbed.
Beyond the safety concerns, these topical numbing agents offer little real benefit. Saliva washes them off the gums within minutes, so any numbing effect is extremely short-lived. The pain of teething comes from deep in the tissue and bone, not just the surface, which further limits what a topical product can do. Homeopathic teething tablets have also drawn FDA warnings in the past due to inconsistent ingredient levels, particularly belladonna.