The father of a family with ADHD has described a shortage of medication for the condition as "unthinkable".
Craig Lester and his children Gary and Caitlin from Chivenor, Devon, have all been diagnosed with attention deficit hyperactivity disorder.
Healthcare professionals were notified of disruption to supplies in September.
The Department for Health and Social Care (DHSC) said issues "are expected to be resolved by the end of the year".
Mr Lester said: "People have got no idea of what it's like to live with a child like this.
"If I have to drive six, seven hours to get something, I will," he added, and said they only have enough medication for the next month.
His daughter Caitlin, 11, said it made her feel "stressed out but also maybe scared sometimes or just can't concentrate".
Henry Shelford, chief executive officer of charity ADHD UK which works to reduce stigma and fund research, said: "I don't know what's going to unravel... it's absolutely terrifying, horrifying and you are just trying to keep it together."
A spokesperson for DHSC said: "We understand medicine shortages can be distressing but we want to reassure patients we are working intensively with manufacturers to increase supply.
"Some of these supply issues have now been resolved, but we know issues remain with others."
Patients are advised to speak with their clinician about concerns.