What are the symptoms ADHD in a 3year old child?

Same. The symptoms of adhd are the same, innatention, hyperactivity and impulsivity, however diagnosing a three year old with adhd raises some eyebrows, symptoms could be severe enough that might merit a diagnosis, but see a behavioral psychologist or a developmental pediatrician, before someone talks you into medications.
Confusing. Diagnosing adhd in a 3 year old is difficult and should only be done by a child psychiatrist or developmental pediatrician. At such an early age, other disorders can look like adhd and developmental disabilities should be excluded first. These children usually have significant hyperactivity, marked impulsivity and diminished need for sleep. They may also have delayed speech.
Disruptive behavior. In toddlers & pre-schoolers is seen in many Neurodevelopmental Disorders. With a strong family history of ADHD or history of prenatal exposure to drugs or alcohol, early-onset ADHD is more likely. Till age 5, an attention span of 3-4 minutes is normal. 6/9 significant symptoms of Hyperactivity/Impulsivity that cause harmful dysfunction at preschool & home for at least 6 months may indicate ADHD.