Why did i get lightheaded when i was having sex on Ritalin ?

i have it for my ADD.....
will i'll be able to have normal sex when i get adjusted i started 4 days ago......am guessing yes because i remember the first day i wasn't able to get erection , but the the next day i was able to get one have way , then the next day i was able to get one but didn't last long , and today i was able to make it last long but it got me lightheaded ,,,anybody got an explanation for this ?

The light headedness was probably caused by a large release of adrenaline which can you light headed. Ritalin is the brand name for a powerful stimulant drug called methylphenidate, it's chemical structure and effects are similar to that of amphetamine.