Does grapefruit, vitamin C, or an antacid actually change how Adderall works?

Grapefruit, vitamin C, and some antacids sit in different pharmacology buckets, and a kitchen experiment is not a way to prove that any of them changed how mixed amphetamine salts work for you. In Canada the mixed-salt amphetamine product is usually Adderall XR, an extended-release capsule, not the immediate-release tablet that US internet threads often mean by Adderall. Amphetamine excretion can be pH-dependent. If the change is persistent, distressing, or affecting daily functioning, bring a brief timeline to the prescribing clinician rather than changing the dose independently. References: https://pdf.hres.ca/dpd_pm/00075816.PDF https://www.camh.ca/en/professionals/treating-conditions-and-disorders/adult-adhd/adult-adhd---treatment/adult-adhd---pharmacotherapy https://www.caddra.ca/medication-chart/

Different for me. I never ran a fruit experiment. I just panicked that Tums and a vitamin C packet were flattening my morning capsule. I brought the bottles to the pharmacy counter instead of dropping either one. Nobody treated my hunch as a lab result. I still take the same mixed salts as prescribed. This is only my anxiety in a Canadian pharmacy line, not a reason to change someone else's routine.

Last winter I ate grapefruit with my Adderall XR because a thread made it sound like a clean experiment. I felt wired and then useless and decided I had proved a thing. I had also slept four hours and had a huge coffee. I told my pharmacist I was not looking for a kitchen verdict. They asked what else I swallowed that morning, including the chewable vitamin. I still eat grapefruit sometimes. I do not treat that week as evidence. Only my scare, not a method for anyone else.