How much different are the effects of Adderall XR when compared to Adderall IR?

I can only speak from experience and as a 115 pound female, but my best average answers for you would be.

1.) depending on your metabolism and digestion I would say anywhere from 45 minutes to begin to notice effects to an hour and a half.

2.) adderall I believe reaches peak plasma concentration in 2 hours, the time release coating within the pill would probably start to break down releasing the other half of the medicine about 4 hours from when you take it. To be safe I would assume one adderall 15xr would last about 8 hours. The lowest dose that will work for you is the best dose. Usually every year they lower your dosage and you climb back up to the dose that best suits you is what happened in my experience. If you don’t need it to last as long then there’s no reason you shouldn’t switch back to the IR. Same stuff chemically between the XR and IR forms is my point the key difference is the rate of absorption which as you probably know can majorly influence the way adderall effects you.

The last two questions ill combine. The severity of the comedown depends on how much you took at one time and also in one day. The less the better when it comes to the comedown. I can take up to 45 without experiencing a terrible comedown. The only difference that matters between the two is the amount of time it takes to absorb the dosage. I didn’t notice any real difference between ir and xr comedown it was more dose dependent.

Usually a Psychiatrist does not make that kind of mistake on accident but I find it weird that he/she would not first talk to you about the change and their reasons why. But on to your questions...
First off, I’ve been taking Adderall for the past 10+ years, have had my bad experiences and my good experiences. I have let the medicine put me at rock bottom, lead me to severe depression, and a lack of will to live. I’ve also had my share of my own ‘Golden days’ on adderall, so to speak. It is a drug which can bring you down to Earth or it can take you to the stars in a sense. Now, your questions..
-How long does it take for it to take effect? A.- It generally takes about the same amount of time that the IR would take. About 40-45 minutes.

-How many hours does adderall 15mg XR last for? A.- This will depend on how much you’ve taken the drug in the past week, give or take a day or two. Say if you’re used to taking a 30 MG IR everyday then chances are you might barely feel this 15 MG XR. But for the sake of the argument let’s say you’ve never had a adderall a day in your life.. One 15MG XR adderall would probably last you about 8-10 hours, the higher MGs you take, the longer you can expect the results to have effect. But keep in mind you won’t feel the adderall the entire 8-10 hours. It likes to fade in and out. You’ll feel the effects for maybe an hour after it kicks in and then it will fade and soon after the effects will rise up again. Off and on again, over and over until depleted.

-Is the XR come down any different (easier or worse) than IR? A.-In my experience, Most Definitly worse. Because the adderall is XR it will keep coming on and fading off repeatedly until the effects are gone completely, and you can expect mild to severe down comes, depending on how much you’ve taken all together from beginning to end of first daily dosage. I believe it is a worse come down because the XR lasts longer in your system and takes more time to dissolve completely throughout your body.

-Should I switch back if I don’t need it to last as long? A.- Yes, you’d probably be better off doing that either way. If you don’t want your adderall IR to last so long, simply don’t take that much of a MG, just break your pill in half by simply placing both your index and middle finger on both sides of the pill at once and push down, the pill will split evenly. And if you feel that the half of the adderall IR was not enough for the day, take the other half when you’re feeling low. Your psychiatrist will most definitly switch you back If you explain the unwanted effects of the XR. Without a doubt.
I hope I helped you in your search for answers about Adderall XR.