Well, my son takes Ritalin for severe ADHD, diagnosed at age 7 by a Licensed Professional Counselor, reviewed by his pediatrician. He did not start meds until the second six weeks of second grade. He had made no friends, was sinking quickly with grades, behavior was getting in his way, he was in trouble at home, hours and hours for just a little bit of homework..................we started him on Ritalin, and it did not take weeks. You could see the difference in one day, by day 8, it was the same as day 3, and not quite enough........it wore off too quickly..........upped the dosage to his maximum for his weight, and there it's been ever since. He's made the A honor roll ever since, has great friends, teachers say he's helpful, cooperative, respectful, and nearly always does what he should (it did not change his WHOLE personality, though I must say he is way more subdued than we are used to, so it does make us think something's wrong with him when we see him on meds!
He was switched to Strattera in 3rd grade, as it was new and the dr. thought it would be good for him, as it was a whole day dose instead of the Ritalin wearing off, having to take again and wait for it to kick in.........he was having some behavior issues during lunch when his meds were worn off. Strattera was awful! He cried and carried on for hours every night. He wouldn't know why he was crying. About 3 weeks in, he told me he wanted to "disappear", and I called the dr. right away. He said he was pulling all of his patients off the drug as all the reports he was getting were similar. Recently, they linked Strattera to depression and suicidal thoughts in children. We are glad he doesn't take it anymore, and doubt if we'll change his meds again due to this experience and how well he does with Ritalin, and it's long-standing safety rate.
Every child is different, and I have met some parents who swear by Strattera, but you asked for my experience!
Edited after reading some other posts to add: We had noticed these symptoms from preschool age, as I have a brother who has ADD and wasn't diagnosed until college. His behaviors were so similar (it does have a familial connection). However, we waited to medicate until it became obvious he wasn't able to conform his behavior to expectations in school, and wasn't able to perform to the best of his abilities. We also tried all the other touted methods, including increasing exercise, decreasing television and video games, increasing sleep, using reward and consequence systems, and changing diet. None of those did the trick. The ritalin did. He doesn't take it outside of school, and we do have behaviors we have to work around, but we know how to help him and we can tolerate him more easily than in a school environment. Sure, it'd be nice if school could work around it, but they don't, and so he needs all the help we can give him, just as if he had any other medical condition. It is a medical condition, actually a physical difference has been determined in the shapes of their brains.
By the by, he was given a series of IQ tests this year. One was inadvertently given during the time his meds were worn off. It was 40 IQ points lower than the other two!