A national Adderall shortage has been declared across the US — after at least half a dozen drug makers said they were running out.

The Food and Drug Administration (FDA) finally acknowledged the problem following months of anecdotal reports of desperate patients rationing the drug or shopping around up to 40 pharmacies for the drugs.

Some ADHD sufferers have already admitted being tempted to turn to the black market — where drugs are spiked with dangerous substances like fentanyl.

The FDA said it would 'continue to use all the tools we have available to help keep supply available for patients' - which could include looking for new suppliers for the US market.

Demand for Adderall rocketed during the pandemic when the move to telephone appointments made it easier to get prescriptions. Labor shortages and supply chain issues may have also had an effect on supply.

Adderall is a schedule two drug in the US — because of the risk of addiction — meaning there are limits on its production. 

At least 2million Americans are estimated to take Adderall, which is prescribed to treat ADHD or rare sleep disorders. 

But more and more otherwise healthy people are getting hold of the drug to help them 'power through' work and studying.

Adderall was heralded as a 'game-changer' for ADHD sufferers when it was approved in the US in 1996.

It is taken as either a fast-acting pill two to three times a day, or a slow-acting version which patients swallow once a day.

It works by boosting levels of the hormones dopamine and norephinephrine in the brain — known as 'feel good hormones' — to help ease ADHD symptoms.

But coming off the drug can cause agitation, higher appetite and tiredness.