Parents demand that prominent warnings are added to a powerful asthma drug that can trigger suicidal thoughts and night terrors in children

Joanna Benz was on montelukast for just two weeks, but she continues to suffer violent nightmares, grisly hallucinations and inexplicable suicidal ‘urges’.

The digital marketing specialist has an extreme form of respiratory illness called brittle asthma and was put on the drug last winter. Ms Benz, from Romsey, Hampshire, said the side effects were appalling, adding that she is ‘absolutely certain’ her hallucinations were caused by montelukast.

‘The nightmares – and that’s an understatement – began on day two,’ she said. ‘They’d go on for ages and I’d struggle to wake up from them.

‘In some, I was being murdered or raped, or my loved ones were being murdered in front of me. They were very detailed, horrific.’

Sometimes she would wake and immediately hallucinate, leaving her unable to distinguish reality from make-believe, and she suffered excruciating pain.

Ms Benz, a motorcycle enthusiast, says she is speaking out to give credence to the accounts of others, especially children, who might otherwise be ignored.

‘People often dismiss what children say because they can exaggerate or make up stories,’ she said. ‘But I’m a 35-year-old woman with no tendencies to exaggerate, and for me this drug is horrific.’

Oliver, eight, is recovering after enduring hallucinations, crushing anxiety and obsessive compulsive traits while on montelukast, but like many, it took his parents a long time to discover the drug was behind his behaviour.

He was two when he was prescribed the drug after a severe asthma attack left him needing hospital treatment.

‘It worked really well for him,’ said his mother Lee, from South London, who asked for her surname to be withheld.

But problems began to emerge which Lee documented in her diary. ‘OMG – now afraid of the water heaters gushing into the pool,’ read one entry about her son who had previously loved swimming. ‘Didn’t sleep well Friday evening, didn’t like the “shadows” on his door,’ read another. Oliver came off montelukast aged four as his asthma improved. But he was put back on it early last year and by summer ‘he was having hallucinations,’ said Lee. ‘He could see things moving – a number on a sign would change. He’d say, “I hear voices that tell me if I don’t do things within a certain amount of time, mummy and daddy are going to be killed.” ’

Deeply concerned, Lee sought a referral to children’s mental health services but as they waited for their appointment, a doctor who heard about the symptoms took her aside and suggested Oliver come off montelukast.

‘Drug companies need to put a label on boxes saying “Look out for these signs”,’ Lee said. ‘This is a serious problem.’

Lily Hodge has twice run out into traffic in disturbing incidents that her mother Kayleigh blames on montelukast.

The eight-year-old was first put on the drug four years ago. Kayleigh, from Newport in South Wales, said: ‘At first I thought, “This is a miracle drug – she’s running around like a normal child without coughing.” ’

But a darker side soon emerged. ‘Lily had been a happy, bubbly child, but she started having nightmares and becoming obsessed with death,’ said her mother, who only made the link when the dosage of montelukast was increased and the problem grew worse.

On one occasion, the youngster ran out into the road after seeing a stick and telling her mother: ‘That stick’s going to die if it gets run over.’

‘She pulled away from me, ran out and stood there in the busy road, crying and holding this stick. I asked Lily why she’d done it and she said, “My brain told me to do it.” ’

Worried Kayleigh searched online for montelukast side effects and Lily was taken off the drug in 2017.

After an initial ‘flare-up’ when she ran into the road for a second time, her symptoms have since reduced.