Hundreds of thousands of Britons who take ADHD medication are at risk of debilitating gut symptoms that leave them constantly fearful of an embarrassing accident. Experts have told the Daily Mail that the stimulant pills, such as methylphenidate, also known as Ritalin, taken by increasing numbers of patients, can drastically affect signals sent between the brain and the bowel, resulting in greater 'urgency'. Meanwhile, some have reported having to stop the 'nightmare' medication - and suffer troublesome ADHD symptoms - as a result of the unbearable digestive side effects. One woman wrote on social media that she'd been rushing to the toilet so frequently that she'd developed 'very sore' haemorrhoids, which is when a swollen vein pushes through the back passage. While the problem is most commonly associated with constipation, the frequent straining and wiping involved with diarrhoea can both trigger and worsen it. 'To put it delicately, my bowels are moving more than they are used to, and this in turn has inflamed my piles,' the woman said.'It’s been manageable until this last week when it has been very sore. Mornings are not fun.' Another told Reddit: 'The damage in the toilet was beyond control... now my tummy is bloated like a balloon and I feel nauseous.' Jacob Wooderson, from London, suffered sudden arrhythmic death syndrome shortly after his dose of Elvanse, also known as lisdexamfetamine, was increasedOthers have told The Mail that the medication makes them rush to the toilet 'immediately', while some say bouts of diarrhoea became 'the new normal' while on the treatment. 'They were a total nightmare for me...I quit them,' one young woman said.The revelations come a week after The Daily Mail published campaigners' concerns about the link between ADHD medication and deadly heart rhythm problems in those with underlying cardiovascular conditions.The charity Cardiac Risk In The Young warned that most of the thousands who are vulnerable to lethal heart side effects will be unaware of their increased risk - as the conditions are typically not diagnosed until a life-threatening event such as a heart attack strikes.Doctors are not obliged to screen patients for cardiac problems before prescribing the drugs, which speed up heart rate and raise blood pressure. It's estimated that around 190,000 people in the UK are currently taking medication for ADHD. Last year the Mail reported the death of 28-year-old Jacob Wooderson, a finance worker from London who suffered sudden arrhythmic death syndrome after his dose of Elvanse, also known as lisdexamfetamine, was increased.Elvanse was listed as a cause of his death. He had been diagnosed with ADHD six months earlier.At the time, coroner Sarah Bourke called on the Government to launch an inquiry into the tablet’s safety, which is ‘increasingly being prescribed in the NHS’. However, no such inquiry was ever commenced. Elvanse was listed as a cause of Jacob Wooderson's death. He had been diagnosed with ADHD six months earlierADHD is a neurodevelopmental condition in which the connections between different brain regions work differently to that of a neurotypical person's, leading to issues with attention, impulsivity and hyperactivity.This can manifest as problems sleeping, an inability to focus and troubles with executive functioning - which is crucial for forward planning and following instructions.Previously it was considered a rare condition that affected children – primarily boys. However there are now 750,000 children and 1.5 million adults diagnosed with ADHD in the UK. As awareness of the condition has grown, so too has the number of people seeking medication. The number of women on ADHD medication has risen 20-fold in the past 15 years, while the number of men has risen 15-fold. Now, experts have raised the alarm about other side effects that, while not life-threatening, can dramatically impact patients' quality of life. Dr James Arkell, consultant psychiatrist at the Central Health London clinic, says most doctors are aware of the dramatic impact on the gut, and must keep an eye on digestive side effects. 'We need to listen to where patients are at with gut problems. Often we have to find a sweet spot - a point where there's enough medication for a benefit, but not so much that it's affecting their bowel.'Some patients, he adds, suffer extreme constipation and require laxatives to ease their discomfort.