Although most kids are diagnosed with ADHD around age 6 (after they start elementary school), it's not uncommon for parents of some kids with ADHD to report seeing signs of the disorder from a younger age. In the past when ADHD was diagnosed in preschoolers, behavior modification therapy was pretty much the only choice for treatment (unless the child was severely affected). However, studies have found that ADHD medications are safe and effective for kids as early as age 4.
Usually the best approach is to start with a behavior therapy modification program, using simple rewards and consequences to help your child regulate his behavior. But this may not be enough for some children; experts have found that when combined with therapy, medication can be very helpful for younger children.
When your child first starts on an ADHD drugs (common ones include Ritalin LA, Concerta, Focalin, Metadate, Dexedrine, and Adderall), you may notice some side effects like stomachaches (especially if the meds are taken without food), headaches, moodiness, disrupted sleep, and poor appetite. Although these symptoms can be worrisome at first, rest assured that they're usually very mild and subside within two to four weeks.