Currently, 6.1% of all American children are being treated with medication for ADHD. The most commonly prescribed medications are stimulants, such as methylphenidate and amphetamines. Stimulant drugs work on the central nervous system by increasing the amounts of hormones called dopamine and norepinephrine in the brain. They are often effective in increasing concentration and decreasing the fatigue common in ADHD. Medications are taken in pill form and can be short lasting (taken multiple times a day) or long lasting (taken once a day in the morning).
Stimulant medications lead to a decrease in symptoms in up to 70% of children with ADHD (source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000197/#B3). The FDA approves the use of stimulant medications in children over age 6, but children as young as 4 or 5 are commonly being prescribed these medications as well (source: https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm269188.htm). Depending on health care coverage, medication can be expensive in the long run, as the benefits are only seen as long as the person continues to take the medication.
While stimulant medications have been deemed to be safe for use in treating ADHD, there are some common side effects, including loss of appetite, sleeplessness, high blood pressure, and headaches. The severity of side effects vary between individuals and depending on medication dosage.
Researchers are still debating the benefits of stimulant medication in treating ADHD, and a number of interesting studies have been done in recent years which question the efficacy and long-term benefits of stimulant medications for ADHD.
For instance, a 2014 study done in Quebec, Canada following a policy change which led to an increase in the prescription of stimulant medications for ADHD found that this increase in medication did not lead to improvement in emotional functioning or academic outcomes among children with ADHD in the medium or long run. (source https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4815037/)