When taken as prescribed, the effects of Adderall (amphetamine and dextroamphetamine) last for about 4 to 6 hours. The effects of Adderall XR last for up to 12 hours because this form of Adderall has been designed to release its contents slowly, over a longer period of time (this is called a sustained release preparation).

Some medications can interact with Adderall and affect how much is absorbed or how quickly or slowly it is excreted, which can change the length of time Adderall lasts for in your body.

Medications that can decrease the absorption of Adderall, lowering blood levels, and decreasing the length of time it lasts for in the body include:

• Fruit juices, such as orange juice or cranberry juice
• Medications that increase the acidity of the stomach contents, such as guanethidine and reserpine
• Vitamin C supplements (also called ascorbic acid).

In addition, KPhos and other urinary acidifiers, or substances such as ammonium chloride or sodium acid phosphate can increase the excretion of Adderall by making the urine more acidic, which also lowers blood levels of Adderall, decreasing the length of time it lasts for in the body.

Other medications or substances, such as those that make the stomach contents more alkaline (less acidic), can increase the absorption of Adderall, which may or may not have an effect on how long it lasts for in the body. Modified release forms of Adderall, such as Adderall XR are more likely to be affected because it will cause the modified release coating to disintegrate faster than what would be expected in the normal stomach environment. Medications that can increase the absorption of Adderall, and increase blood levels of Adderall include:

• Gastrointestinal alkalinizing agents, such as sodium bicarbonate
• Proton pump inhibitors (PPIs), such as omeprazole or pantoprazole.

In addition, urinary alkalinizing agents (such as acetazolamide and some thiazides) can decrease the excretion of Adderall by making the urine more alkaline, which can increase blood levels of Adderall and increase the length of time it lasts for in the body. Other medications that can prolong the effect of Adderall include monoamine oxidase inhibitors (MAOIs) or medications which have MAOI-like activity, such as isocarboxazid, linezolid, methylene blue, procarbazine, selegiline, and tranylcypromine which slow the metabolism of Adderall.