Most side effects are minor and disappear over time or if the dosage level is lowered." Q4: Can their children become addicted to methylphenidate?

While there has been a great deal of publicity in the media about how the drugs prescribed for ADHD have been abused, it is important to make a clear distinction between the pharmacological use of such drugs to treat behavioral disorders and individuals using them for recreational purposes. Individuals without ADHD who are self-prescribing, and using such medications to stay awake and focused for long periods of time are not carefully monitoring their doses to facilitate a normal existence, but are striving to test their limits.

Q5: Would consuming an addictive drug now increase my child's chances of abusing drugs later in life?

According to the National Institute of Drug Abuse (NIDA): "research thus far suggests that individuals with ADHD do not become addicted to their stimulant medications when taken in the form...

Furthermore, several studies report that stimulant therapy in childhood does not increase the risk for subsequent drug and alcohol abuse disorders later in life." In fact, poor performance in school and negative peer, family, and teacher relationships is far more likely to be correlated with drug abuse: and negative social and academic experiences are what drug treatment is ultimately attempting to prevent or mitigate in children with ADHD.
Reference

Attention deficit hyperactivity disorder (ADHD) (2009, June 15). NIMH (National Institute of Mental Health). Retrieved January 25, 2010 at http://www.nimh.nih.gov/health/publications/attention deficit hyperactivity disorder/complete-index.shtml

NIDA InfoFacts: Stimulant ADHD Medications - methylphenidate and amphetamines.

(2009, October 2). National Institute on Drug Abuse (NIDA) Retrieved January 25, 2010

at http://www.drugabuse.gov/InfoFacts/ADHD.html