Most babies significantly reduce mouthing behavior between 12 and 18 months of age, though some continue well into their second year. The habit peaks between 6 and 9 months, when babies are most actively using their mouths to learn about objects, and then gradually tapers as they develop more sophisticated ways to explore with their hands and eyes.
Why Babies Use Their Mouths to Explore
Babies aren’t putting things in their mouths to annoy you. Their mouths are genuinely better sensory tools than their hands during the first year of life. The lips, tongue, and inner cheeks are packed with nerve endings that detect texture, shape, temperature, and firmness with far more precision than an infant’s still-developing fingers can manage. When a baby mouths a toy, sensory neurons relay detailed information from the face and mouth to the brainstem, giving the baby a rich picture of what they’re holding.
This starts as a reflex. Newborns are wired for sucking, and by about 3 months, most babies begin bringing their hands and objects to their mouths deliberately. Biting on fingers, toes, or toys activates the same reflexive sucking and swallowing movements, which then gradually transitions from an innate reflex into a learned, purposeful behavior. In other words, what begins as instinct becomes a genuine exploration strategy.
When Mouthing Peaks and When It Fades
Research consistently shows that mouthing is most frequent between 6 and 9 months. During this window, babies presented with objects spend a substantial portion of their time systematically exploring them with their mouths. This coincides with the age when most babies can sit up and grasp objects reliably but haven’t yet developed the fine motor skills to examine things carefully with their fingers.
After 9 months, mouthing starts to decline as babies get better at turning objects over in their hands, poking, pulling, and banging them. By 12 months, many babies mouth objects less often, and by 18 to 24 months, most toddlers have largely moved on to visual and manual exploration. That said, occasional mouthing during toddlerhood is still normal, especially with new or interesting textures.
There’s no single day when the behavior switches off. Some children stop closer to 12 months, others closer to 2 years. If your child is still regularly mouthing non-food items after age 2, it’s worth mentioning to your pediatrician, particularly if they’re eating non-food substances. The clinical threshold for concern (a condition called pica) requires that the behavior persist for at least one month in a child who is at least 24 months old and is eating things that aren’t food, not just mouthing them.
Teething Makes It Last Longer
Teething adds a second reason to chew on everything. The first teeth typically appear around 6 months, right when exploratory mouthing is already at its peak. But teething continues in waves until roughly age 2 to 3, when the last baby molars come in. During active teething episodes, babies and toddlers bite and chew on objects to relieve gum pressure, even if they’ve otherwise outgrown the exploratory phase. Signs that mouthing is teething-related rather than exploratory include fussiness, irritability, difficulty sleeping, drooling, and loss of appetite alongside the chewing.
This overlap means that a 15-month-old who seemed to have stopped mouthing everything may suddenly start again when a new tooth is pushing through. It doesn’t mean they’ve regressed. Once the tooth breaks through, the behavior typically drops off again.
Keeping Your Baby Safe During This Phase
Since mouthing is both normal and necessary, the goal isn’t to stop it. It’s to make sure what goes into your baby’s mouth is safe. The two main risks are choking and chemical exposure.
Choking Hazards
U.S. safety regulators define a choking hazard as any object that fits inside a test cylinder roughly 1.25 inches wide and 2.25 inches long, which approximates the size of a young child’s fully expanded throat. If something fits through a standard toilet paper roll, it’s generally too small for a child under 3. Check your floors regularly for coins, button batteries, small toy parts, and anything else at that size. Button batteries deserve special attention because they’re both a choking risk and a chemical burn risk if swallowed. Make sure battery covers on remote controls, key fobs, and musical toys are secure.
Chemical Safety
Babies who mouth plastic toys can be exposed to chemicals used to make plastics flexible. Several types of softening chemicals called phthalates have been restricted in children’s toys to no more than 0.1% of plastic parts, with stricter rules applied to toys specifically designed to be put in the mouth. When buying teethers or toys for babies under 2, look for products labeled phthalate-free and avoid anything with a strong chemical smell. Painted toys should use non-toxic, lead-free paint.
Household Poisons
The American Academy of Pediatrics recommends installing safety latches on any cabinet a crawling or walking child can reach, particularly those containing cleaning products, medications, or laundry detergent pods. Single-use laundry packets are highly concentrated and toxic if a child bites into one. Store them in sealed containers inside locked cabinets, out of sight. The same goes for nicotine products, unfinished alcoholic drinks, and medications, which should stay in their original child-resistant containers.
What’s Normal and What Isn’t
Frequent mouthing in a baby under 12 months is completely typical and actually a sign of healthy sensory development. Gradually decreasing mouthing between 12 and 24 months is also normal. Occasional mouthing of new objects even at age 2 or 3 isn’t unusual, especially during teething.
What may warrant a conversation with your pediatrician is a child older than 2 who consistently eats non-food items like dirt, paint chips, or paper. This goes beyond normal exploration into territory that could indicate a nutritional deficiency (particularly iron or zinc) or a behavioral pattern that benefits from professional guidance. The key distinction is between mouthing objects to explore them and actually consuming non-food materials on a regular basis.