(Natural News) The United States is now experiencing a massive shortage of extensively used Big Pharma drug for attention-deficit/hyperactivity disorder (ADHD) Adderall.

Patients in California, Indiana and Michigan who ordered over the past two months at CVS Health Corp. and Walgreens Boots Alliance Inc. pharmacies were told the drug was out of stock. (Related: Amphetamine ADHD drug Adderall facing supply crunch, survey finds.)

Most of the time, they were told they will have to wait more than a week so they can buy the drug that is prescribed to be taken every day.

"There are supply chain challenges with this drug," Walgreens spokesperson Rebekah Pajak said. She added the issues are affecting both instant-release and extended-release Adderall. On the other hand, CVS spokesperson Matthew Blanchette said the company's pharmacies are able to fill Adderall prescriptions "in most cases.