Early in 2025, BBC Investigations Correspondent Noel Titheradge published his first story about a category of prescription drug with unusual side effects.

People who take dopamine agonist drugs for conditions like Parkinson’s disease or Restless Legs Syndrome often report impulse control disorders - problems with gambling, compulsive eating or shopping, or hypersexuality.

He wasn’t expecting the response. After that first article was published more than 200 people got in touch - that’s me, they said, that’s my partner, that’s my dad.

So Noel started digging.

Details of organisations offering help and support with some of the issues raised are available at bbc.co.uk/actionline.

If you have any concerns about medication you’re taking, speak to your doctor.

Impulse control disorders are a common side effect of dopamine agonist drugs - it’s generally accepted that they will affect around 1 in 6 people taking these drugs for Parkinson’s.

So why are these side effects so hard to talk about? How can people get past their guilt and shame to access the support they need?

And if subtle changes in the activity of chemicals in our brain can cause us to behave so differently - what is personality?

Details of organisations offering help and support with some of the issues raised are available at bbc.co.uk/actionline.

If you have any concerns about medication you’re taking, speak to your doctor.

Presenter: Noel Titheradge Producer: Lucy Burns Editor: Matt Willis A BBC News Long Form Audio production

Respected local solicitor Andrew is sent to prison - but the devastating impact of the side effects of his Parkinson’s medication continues.

BBC Investigations Correspondent Noel Titheradge has been contacted by more than 200 people about their experience of behavioural side effects of dopamine agonist drugs.

So who’s taking responsibility? We hear from pharmaceutical companies, regulators and doctors. There have been significant developments in the way these drugs are used - but what effect have they had?

Details of organisations offering help and support with some of the issues raised are available at bbc.co.uk/actionline.

If you have any concerns about medication you’re taking, speak to your doctor.

Presenter: Noel Titheradge Producer: Lucy Burns Editor: Matt Willis A BBC News Long Form Audio production

Andrew’s a respected local solicitor when one day he’s arrested. He has defrauded his elderly clients of more than £600,000, which he’s spent on sex workers and antiques.

His wife Frances and daughter Alice are shocked - this seems completely out of character. Then they learn there could be a connection to Andrew’s Parkinson’s medication.

But will the judge accept this as mitigation for his crimes?

Details of organisations offering help and support with some of the issues raised are available at bbc.co.uk/actionline.

If you have any concerns about medication you’re taking, speak to your doctor.

Presenter: Noel Titheradge Producer: Lucy Burns Editor: Matt Willis A BBC News Long Form Audio production

Lucy’s stumbled on a connection between her gambling problem and her medication. But her mental health team says they don’t know what she’s talking about.

Freddie’s reached breaking point. And, one day, he notices his dad’s medication leaflet on the kitchen table, sparking a full-blown crisis.

It’s been known for more than two decades that drugs affecting dopamine levels in the brain have potential side effects including impulse control disorders like hypersexuality, or compulsive shopping or gambling.

Warnings have been added to patient information leaflets - but many of the people who’ve contacted BBC investigations correspondent Noel Titheradge about their experiences say the risks weren’t made clear.

Why weren’t they warned about the potential side effects of these medications before it was too late?

Details of organisations offering help and support with some of the issues raised are available at bbc.co.uk/actionline.

If you have any concerns about medication you’re taking, speak to your doctor.

Presenter: Noel Titheradge Producer: Lucy Burns Editor: Matt Willis A BBC News Long Form Audio production

Lucy’s on her lunchbreak when she tries her first scratchcard - soon, she’s hooked. She’s never been interested in gambling before, but after a few months the glove compartment of her car is full of scratchcards. And then she starts gambling online…

Lucy’s taking a medication called Aripiprazole for her mental health condition. It’s a partial dopamine agonist - a different mechanism to the dopamine agonist drugs used for Parkinson’s and Restless Legs Syndrome that we’ve heard about in previous episodes.

But it’s got similar side effects. For Lucy, this means compulsive eating, hypersexuality - and a gambling problem that’s spiralling out of control.

Details of organisations offering help and support with some of the issues raised are available at bbc.co.uk/actionline.

If you have any concerns about medication you’re taking, speak to your doctor.

Presenter: Noel Titheradge Producer: Lucy Burns Editor: Matt Willis A BBC News Long Form Audio production

Lisa has Restless Legs Syndrome - it feels like her legs are on fire and they keep moving around. It’s affecting her sleep, so she’s pleased to hear that there’s a treatment: a commonly used Parkinson’s medication called Pramipexole. The prescriber doesn’t mention any side effects.

But Lisa’s dosage of Pramipexole keeps increasing as her symptoms keep returning, and she starts behaving in ways that feel out of character. After an argument with her husband, she starts an affair with a man she meets online. Soon she’s meeting strangers for sex.

And even while her personality’s changing, her condition keeps getting worse…

Details of organisations offering help and support with some of the issues raised are available at bbc.co.uk/actionline.

If you have any concerns about medication you’re taking, speak to your doctor.

Presenter: Noel Titheradge Producer: Lucy Burns Editor: Matt Willis A BBC News Long Form Audio production

When BBC Investigations correspondent Noel Titheradge first started looking into this story, he set about finding insiders who knew what had gone on inside the pharmaceutical companies that made them. He contacted former staff and officials, cold called potential whistleblowers - and then he got lucky.

Someone shared an internal report from the drug company GlaxoSmithKline which revealed that they’d been aware of fifteen cases of “increased libido” in patients taking their dopamine agonist Ropinirole, including cases of paedophilia and indecent behaviour.

The report had been published in 2003, three years before warnings appeared on patient leaflets - and thirteen years before Steve started taking the drug.

Details of organisations offering help and support with some of the issues raised are available at bbc.co.uk/actionline.

If you have any concerns about medication you’re taking, speak to your doctor.

Presenter: Noel Titheradge Producer: Lucy Burns Editor: Matt Willis A BBC News Long Form Audio production