NEXSTAR (WASHINGTON) – A nationwide shortage of Adderall has left many people with attention-deficit/hyperactivity disorder, or ADHD, struggling to find medication that they rely on.

Millions of people in the United States are prescribed the drug to help manage their ADHD. Zac Bowling, who lives in The San Francisco Bay area of California, is one of them. But recently, Bowling says, his local pharmacy couldn’t fill his prescription.

“So I called 14 other pharmacies and nothing is available, none of them,” Bowling said. “It’s a massive rollercoaster.”

The U.S. Food and Drug Administration blames the shortage on manufacturing problems at one major producer, Teva.

Dr. David W. Goodman, an assistant professor in psychiatry at the Johns Hopkins School of Medicine, says there has also been an increase in awareness about ADHD among both patients and physicians. He says that’s driving up demand.

“So they seek an evaluation, and more and more prescribers are comfortable enough to make a diagnosis and prescribe a medication,” Goodman said.

His advice for patients is not to panic.

“If it’s necessary, call your prescriber and see if there’s an alternative dose that can bridge you until you can get back on the dose that you’re prescribed,” Goodman said.

However, Dr. Goodman does add that finding the right alternative can take some time.

Duane Gordan, president of the Attention Deficit Disorder Association, says adjusting medication can disrupt the delicate balance between medication and life habits that many people use to manage their ADHD.

“It adds in many, many challenges to an already stressful situation,” Gordon said.

If a person with ADHD is struggling to cope with their disorder, he says that can have consequences at work, for their family and in their community.

“The ripples will be felt, not just for that person, but for the people around them,” Gordon said.

For now, with the shortage expected to last for several weeks, people like Zac are left waiting for solutions.

“I feel vulnerable, being sort of deprived of the thing that makes me function as well as I can,” Bowling said.

In a statement to Nexstar’s Washington DC bureau, an FDA spokesperson said:

“The FDA is in frequent communication with Teva Pharmaceuticals, one of the producers of the ADHD medication, regarding supply. We are continuing to work closely with Teva to monitor the overall availability of this drug and to assist as needed to resolve the shortage. We will continue to update our website with new supply information as it becomes available. “