Why is my toddler suddenly hitting?

What the evidence says

This is one of the most common and normal toddler behaviors there is. A large study tracking children from 6 to 24 months found that hitting is expected behavior, with the majority of parents reporting it, and it tends to peak around 18 months. Your toddler isn't being 'bad' -- their brain is still building the self-control and language skills needed to handle big feelings like anger, frustration, jealousy, or being overwhelmed.

Common triggers include being tired, hungry, overstimulated, scared, or not having the words to say what they want. A slow-to-warm-up child might hit a new caregiver, while a child who is overwhelmed by noise or crowds might lash out to create distance. Sometimes hitting starts right after a change at home, like a new sibling or a move.

What helps: stay calm rather than reacting with anger, firmly say something like 'no hitting, hitting hurts,' and then help them find words or another outlet for the feeling. Consistency across all caregivers matters, and praising gentle behavior works better than punishment, which toddlers under 3 often don't really understand yet. Hitting alone at this age is not a red flag.

It becomes worth mentioning to your doctor if it is very frequent (most days for weeks), causes injury, doesn't improve with consistent response, or comes with other worrying signs like loss of previously learned skills.