I feared my son had a brain tumour but he’d been poisoned with vitamin D

When seven-year-old Roo suddenly became ill last year (losing weight and drinking water), his doctors and parents feared he might have a brain tumor.

But investigations revealed that he had accidentally been poisoned by an overdose of vitamin D, which was prescribed for growing pains.

Roo’s bottle of vitamin D3 drops, which were about seven times more concentrated than they should have been, came from one of two bad batches distributed in the UK.

The dosage caused acute kidney injury in Roo, and a leading expert told BBC News that the little boy would have died if he had finished the prescribed treatment.

Vitamin D is a vital nutrient that regulates calcium and phosphate for healthy bones, teeth and muscles. It is taken as an over-the-counter supplement by millions of adults.

However, higher doses of Vitamin D prescribed by doctors are still classed as a food supplement and are not regulated by the medicines regulator MHRA.

Instead vitamins and food supplements are monitored by the Food Standards Agency.

The MHRA said it was working with the FSA to ensure public safety.

But a leading expert told BBC News the medicines watchdog should look at changing the way vitamin supplements are regulated.

To relieve severe pain in his legs, Roo was prescribed high-dose vitamin D3 drops for 12 weeks in December 2024.

This came after he was referred to paediatricians at Crosshouse hospital, near his home in Kilmarnock, Ayrshire.

Blood tests showed he was fit and healthy, but his vitamin D levels were slightly lower than normal.

He was given supplements containing vitamin D3, also known as cholecalciferol, to raise the levels in his blood.

Over the next few weeks, Roo became sleepy and lost his appetite.

His mother, Carys Hobbs-Sargeant, said he started losing weight and started drinking water “like he was in the desert.”

Roo also had bouts of vomiting and had trouble eating throughout January.

“He was really sick,” Carys said.

“He lost more than 10% of his body weight in six weeks. He had big eyes, was very tired and couldn’t eat.”

When Roo saw the pediatrician again, he was immediately taken to the hospital.

Initial blood tests showed that Roo had acute kidney injury and that his kidneys were severely dehydrated, so doctors began investigating the cause.

She initially had no concerns about the vitamin D prescription, as she had only completed two-thirds of the recommended dose.

However, his condition continued to worsen.

“He had hypercalcemia and they were worried about how high the calcium in his blood was,” said his mother, Carys.

“They were checking for a brain tumor and we were getting ready to take an MRI of his brain.”

Roo’s mysterious case was also being investigated by teams at the Royal Children’s Hospital Glasgow, and it was a chance phone call to an endocrinologist there that provided the missing piece of the puzzle.

A colleague in Manchester had asked him if they had seen a “bad batch” of vitamin D3.

Details of the party were able to be cross-referenced by Roo’s team with the bottle Roo still dribbles from every day.

“His body was doing weird things, he was actually poisoned from this bad batch,” Carys said.

“You felt relieved and lucky and angry at the same time that it wasn’t cancer, but it was something that happened to him. Essentially poisoning.”

Roo’s drop bottle was paired with one of two defective batches of TriOn Pharma’s Aactive D3 supplement distributed across the UK.

The drops were seven times the concentration they should have been.

The faulty batches were recalled by the Food Standards Agency (FSA) on January 9, but Food Standards Agency Scotland (FSS), which is responsible for the recall north of the border, said the alert had not reached the correct departments.

The investigation also revealed that the Ayrshire pharmacy that distributed the drops did not receive the manufacturer’s recall email until nearly three months after it was issued.

Medicines alerts from the MHRA should have gone to the pharmacies’ high-priority clinical inbox and then been read immediately.

Prof Stuart Ralston, of the University of Edinburgh, is a former chair of the MHRA’s Medicines for Human Use Commission. He said Roo’s shocking case showed why the MHRA should consider taking over the regulation of vitamin supplements.

“The product is estimated to contain seven times more vitamin D than it should have,” he said.

“I have never come across this in my career of over 40 years.

“He was supposed to have a 12-week course. If he had done that it would have been 3.5 million units and luckily he didn’t because if he had he would have undoubtedly died.”

If it had been regulated as a supplement, Ralston said, Roo’s doctor would likely have received an immediate alert.

The MHRA said it was the FSA’s duty to regulate dietary supplements and they were working together to ensure the public’s safety.

The FSS said it was working closely with the Food Standards Agency and local authorities to ensure product recalls were communicated effectively.

The Scottish government told Carys it had escalated the issue of regulation and further recalls to the UK Department of Health and Social Care.

A month before Roo started her vitamin D3 treatment, Kayan Khan, from Sheffield, was prescribed the same brand of supplement.

Kayan, now 13, was already living with several complex medical conditions, including chronic kidney disease, and the eight-week vitamin D treatment his doctor recommended was in line with recommendations.

Kayan was admitted to hospital in Sheffield in February 2025 with high levels of calcium and reduced kidney function.

A letter from Sheffield Children’s NHS Foundation Trust to her mother Alaina said doctors had difficulty checking calcium levels and vitamin D toxicity was found to be “well above what would be expected from standard supplementation”.

The exact amount could not be confirmed because Alaina did not keep the bottle containing the vitamin drops, but the letter stated that the “plausible explanation” for her toxic level was increased vitamin D intake.

Although news of the FSA recall was once again conveyed to hospital doctors and local pharmacies, it did not reach Alaina.

He said he only learned of the recall in April 2025.

Kayan’s kidney function has deteriorated significantly, and although he has improved somewhat now, he may need a transplant in the future.

“As a parent, as a mother, I’m disappointed,” she said.

“I can’t help but feel like I’ve been slowly poisoning my son for eight weeks.”

Dr Jeff Perring, executive medical director at Sheffield Children’s NHS Foundation Trust, said its standard practice was to ask GPs to prescribe medication, but they followed strict procedures to notify patients and families directly about recalls of prescribed medicines.

Drop manufacturer TriOn Pharma said it launched an immediate recall after a problem was identified and notified the FSA and MHRA in line with requirements.

“Recall notices have been issued to all direct customers through established channels for onward communication throughout the supply chain,” they said.

“We continue to work with authorities to support patient safety.”

It took about a year for Roo’s vitamin D levels to return to the safe range, and Carys said the long-term effects are still unclear.

“He went from being an outdoor forest school kid to someone who now needs a wheelchair to travel longer distances,” he said.

“He didn’t immediately go back to the person he was before, and he still deals with it every day.”