Early signs of autism in toddlers: what to look for, age by age

Most parents do not arrive at the question “is my child autistic?” through a checklist. They arrive through a feeling — that something about how their child connects, plays or reacts is different from other children the same age, and that the difference is not going away.

That feeling is worth taking seriously. Parent concern is one of the strongest early predictors of a later autism diagnosis, and it is often accurate months before a formal assessment happens.

This guide sets out what early signs actually look like day to day, organised by age. It is not a diagnostic tool — only a qualified clinician can diagnose autism — but it will help you describe what you are seeing clearly enough to be taken seriously.

The two areas clinicians look at

Every autism assessment, whatever the country or system, examines the same two areas:

1. Social communication and interaction — how your child shares attention, uses gestures and language, and connects with people.
2. Restricted or repetitive behaviours and sensory differences — repeated movements, intense interests, a strong need for sameness, and unusual responses to sound, texture, light or movement.

A child needs differences in both areas for an autism diagnosis. This matters, because a toddler who is late to talk but otherwise shares, points, pretends and seeks you out is showing a different profile from a toddler who is late to talk and rarely brings things to show you.

Signs at 12 months

At one year old, the most informative signs are about shared attention — the back-and-forth loop of noticing something together.

• Does not respond to their name consistently when you are close by and there is no competing noise
• Rarely points at things to show you something interesting (as opposed to pointing to request)
• Does not follow your point or your gaze to look at what you are looking at
• Little back-and-forth babble, few gestures like waving, clapping or reaching up
• Does not check your face for reassurance in a new situation
• Repetitive movements such as hand flapping, finger flicking or body rocking
• Unusually strong reactions to everyday sound, or unusually little reaction

A single item on this list is not meaningful. A cluster of them, persisting over weeks, is worth raising.

Signs at 18 months

Eighteen months is when many health systems run a routine developmental check, and it is the age at which screening tools are most commonly used.

• Few or no single words, or words that appeared and then faded away
• Does not bring objects over simply to share them with you
• Little pretend play — a toy phone is spun or lined up rather than “talked into”
• Prefers to play alongside rather than with, even with familiar adults
• Takes your hand and uses it as a tool rather than gesturing or asking
• Repeats phrases from television or from you, out of context (echolalia)
• Lines up toys in careful order, and is distressed if the order changes
• Strong distress at transitions — leaving the park, turning off a screen, changing rooms

Loss of skills is always worth reporting

If your child had words, gestures or social behaviours and then lost them, tell a clinician promptly and clearly. Regression occurs in a meaningful minority of autistic children, typically between 15 and 24 months, and it should trigger an assessment rather than a “wait and see” response.

Signs at 24 months

By two, the gap between an autistic child’s social profile and their peers’ often becomes more visible — especially in group settings like a toddler group or nursery.

• Fewer than about 50 words, or no two-word phrases such as “more juice”
• More interested in objects and systems than in other children
• Does not imitate — waving back, copying a silly face, joining in with an action song
• Speech used mainly to request, rarely to comment or share (“look!”, “wow!”)
• Intense, narrow interests: wheels, fans, letters, numbers, specific characters
• Needs routines followed exactly, with meltdowns when they are broken
• Sensory-seeking (spinning, crashing, mouthing) or sensory-avoiding (covering ears, refusing textures)
• Eats a very narrow range of foods, often sorted by texture or colour

If food is a significant battleground in your house, our guide to food selectivity in autistic children explains what is really going on and what tends to help.

Signs at 30 to 36 months

Older toddlers who were not identified earlier often show subtler patterns.

• Conversation is one-sided — long monologues about a favourite topic, little turn-taking
• Difficulty with imaginative or role-play games with other children
• Very literal understanding; confused or upset by jokes, sarcasm and idioms
• Strong preference for playing alone, or for directing other children’s play precisely
• Meltdowns after nursery or preschool, but reportedly “fine” while there
• Advanced skills in one area — reading early, memorising facts — alongside clear difficulty with everyday social exchange

That last pattern, sometimes described as an uneven profile, is one of the most commonly missed. So is the “fine at school, falls apart at home” pattern, which usually reflects a child holding themselves together all day and releasing it where they feel safest.

Signs that look different in girls

Autistic girls are diagnosed later and less often than boys, largely because their presentation is compared against a male-derived stereotype. Common differences include intense but socially typical interests (animals, characters, particular books), copying other children’s social behaviour closely, one strong friendship rather than none, and distress that turns inward as anxiety rather than outward as disruption.

We cover this in detail in signs of autism in girls.

What is not a sign of autism

It helps to rule some things out, because the internet is full of them:

• Toe walking on its own. Common in toddlers generally.
• Being shy or slow to warm up. Shyness involves wanting connection but feeling anxious about it.
• Being a picky eater. Very common at 2 to 3; the autism-linked pattern is far more extreme and sensory-driven.
• Tantrums. Universal at this age. The relevant question is what triggers them and what ends them — see meltdown vs tantrum.
• Preferring adults to other children. Common in only children and in verbally advanced toddlers.

What to do next

If you are told to wait and see and your concerns persist, you are entitled to ask again. Persistent parental concern plus documented examples is what moves a case forward. Our step-by-step guide to getting an autism assessment covers exactly what to say and who to say it to.

Why acting early matters

Early support is not about “fixing” your child. It is about giving them communication tools and sensory strategies while their brain is at its most adaptable, and about giving you a framework for understanding behaviour that would otherwise be baffling. Families who understand why transitions cause distress respond differently — and the child’s daily life gets easier long before any formal support begins.

You do not need a diagnosis to start. Visual schedules, predictable routines, reduced sensory load and communication support all help any child who needs them.