Driving my son’s snake, Todd, a 3ft python wrapped in a pillowcase, to a Brighton vet in August was child’s play compared to the rest of what had gone on that summer. My son, who is 32 and has Asperger’s syndrome, had been served with an eviction notice from his rented flat, having been on what was effectively speed for the previous eight months. Since early July, when his three young carers resigned, he had been visited by the NHS mental health crisis team twice a day. This team, with great skill, calling on him in twos, had managed to get him off what — for him, and for anyone associated with him — had turned out to be a pernicious drug, Atomoxetine.

Unfortunately, he loved being on it and I could see why; it made him feel confident (those with Asperger’s usually suffer from high anxiety and are prey to obsessions) and, unlike with Olanzapine, the medication he had previously been on for several years, with Atomoxetine he did not feel sleepy during the day and did not crave sweet foods or alcohol. He was super-energetic and seemed to be enjoying life for the first time.

However, he was also manic and un-able to listen to what anyone had to say. My American cousin, meeting him for the first time, said he reminded her of adults she’d known on Adderall, which, I gather, is a drug containing amphetamine and is often used to treat ADHD.

One major result of my son’s manic behaviour was that he fell out with two important people in his life: a special needs teacher he’d known since he was ten, at our side in every previous crisis, including when he was sectioned at 17; and a former counsellor now a friend, who had patiently fielded my son’s innumerable phone calls over a period of several years, dispensing sensible advice.

Even these two helpful older women had now had their fill, the first finally snapping when he threatened to send the ex-husband of a member of the royal family to ‘get’ her. And his devoted godmother Cate said she could not have him to stay again till he came off Atomoxetine. At a charity Christmas carols event, he had charged into the ladies’ lavatory and harangued the terminally ill woman she had brought as her guest.

I had guessed what my son was up to when, in October last year, he had claimed to have ADHD. As a teenager he had been briefly on Ritalin and had liked the way it helped him concentrate on schoolwork. He was not on it long, but for years afterwards had yearned for a similar medication — he had heard of Concerta, like Ritalin for adults — and knew that a diagnosis of ADHD could lead to this type of drug being prescribed. Therefore his sympathetic young care team (my son cannot live without help), operating on a ‘client-led’ policy, took him to an experienced psychoanalyst whom I trusted and who had previously seen my son as a patient. The psychoanalyst, together with my son’s NHS Brighton psychiatrist, put my son on to Atomoxetine.

There were other changes in behaviour as a result. He had always been very careful with money (furious if I bought a too pricey balsamic vinegar, insisting on taking it back) and going each Sunday to car boot sales to find bargains. Now, on Atomoxetine, he suddenly forked out hundreds of pounds, first on Todd the python and then on a Russian Blue kitten that was delivered from the Midlands. My son promptly lost its pedigree papers and, annoyed by the way the kitten, which he named Sebastian, scratched his furniture, gave him away to a kind lady, telling me: ‘Sebastian’s packed his bags and gone to Russia!’

Then there were visits to random psychics. My son kept quoting one called Henry, who introduced him to the concept of ‘old souls’ and ‘new souls’. Those my son disliked in his life were now relegated to ‘new souls’. He also made several threats of violence and claimed to have assaulted a man outside Asda. Once when I was talking to him on his mobile, I heard him in the background having an altercation on a Brighton bus. I was also subjected to barrages of texts containing analyses of friends and relations, or nuggets of advice. After I had flu: ‘u must get sarano ham from Spanish shop. Bevyl found it made him stronger towards his departure 2 the other side’. (Beville was a deceased friend.) Or: ‘Cate only eats sandwiches like Snow White.’ (His black-haired, ivory-skinned godmother hates cooking and eats very little.)

Meanwhile my son had himself lost a huge amount of weight and his face looked pinched and ill. However, he seemed to feel omnipotent and one of his voice messages even said: ‘You will soon no longer have an Asperger’s son’, which I found poignant.

He then took care to sabotage two appointments at the Brighton psychiatrist, as he had guessed, rightly, that he was about to be taken off Atomoxetine. His young carers seemed tied by the 2015 Mentality Capacity Act — ‘designed to protect and empower individuals who may lack the mental capacity to make their own decisions about their care and treatment… Just because someone makes what those caring for them consider to be an “unwise” decision, they should not be treated as lacking the capacity to make that decision.’

I am not an expert on medication and am still not sure why Atomoxetine (which I gather does not have the same ingredients as those in Ritalin or Concerta or Adderall) had this effect on my son. All I know is that it was disastrous. I hope he never manages to order it on the internet.

Now, for the first time for 17 years, he is on no medication at all and is depressed — mainly about all the consequences of his behaviour, which he has still not accepted are at all his fault: the eviction from the flat he liked, falling out with those two helpful women, and the departure of the young carers of whom he was fond. I was unable to take him to Mallorca, a place he loves, or on our family holiday to Devon, as his behaviour was too wild.

But I am not sure he is capable of really understanding that his reaction to Atomoxetine was a major cause of all this. A few days ago, he begged the Brighton psychiatrist to put him back on it. Thank God, the psychiatrist refused.