After two antidepressants were prescribed at the same time, I suddenly developed serotonin syndrome, which is uncommon, but can become life-threatening. Here’s what happened to me – and the early warning signs everyone taking serotonin-boosting medication should know.
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For someone who is usually happy-go-lucky, what happened to me one morning was completely out of character.
The confusion came first, followed by tears that simply wouldn’t stop. My body began making jerky movements, my pupils became noticeably dilated and I found myself experiencing irrational thoughts alongside an overwhelming feeling of dread and doom.
I felt as though something was seriously wrong, but I had no idea what.
I was fortunate enough to get a quick appointment with my private GP after feeling too unwell to make it to my usual NHS doctor. Within a short period of time, he identified what was happening: serotonin syndrome, a potentially serious reaction caused by excessive serotonin activity in the nervous system.
The diagnosis was frightening – but knowing what was happening meant I could act quickly.
Had I continued taking the medication that had been prescribed by a psychiatrist just two days earlier, my symptoms could have become significantly worse.
How my panic attacks led to serotonin syndrome
The backstory began around six months earlier, when I started experiencing acute panic attacks seemingly out of nowhere.
My father had suffered from panic attacks, so I recognised some of the symptoms. I would feel dizzy and experience the overwhelming urge to fight or flee whenever I went out.
I initially tried CBT and therapy before being prescribed a low dose of the antidepressant sertraline, which is commonly used to treat conditions including panic disorder.
It seemed to help, but I was still struggling.
My doctor suggested that I see a psychiatrist to discuss whether I was taking the most appropriate medication.
Following an hour-long consultation, the psychiatrist added another SSRI – a type of antidepressant that affects serotonin, a chemical messenger involved in mood and anxiety.
It was after starting the second medication that everything changed.
When I knew something was seriously wrong
Within two days, I began experiencing symptoms that were completely unlike anything I had experienced before.
I became increasingly confused and disorientated, couldn’t speak coherently and had to rely on my husband to explain what was happening when I contacted my GP.
I was crying uncontrollably and experiencing jerky movements, dilated pupils, irrational thoughts and an intense feeling that something terrible was about to happen.
My GP quickly recognised the combination of symptoms and medications as potentially indicating serotonin syndrome.
He told me to stop taking the second medication immediately.
Within a day, I began to feel much more like myself as the effects of the additional medication subsided.
The experience left me shaken, particularly because I had never heard of serotonin syndrome before.
It also made me realise how important it is to understand the medications we take – particularly when more than one drug affects the same chemical pathways in the body.
What is serotonin syndrome?
“Serotonin syndrome is a potentially serious reaction caused by too much serotonin activity in the nervous system,” explains Dr Ahmed Shoka, consultant psychiatrist at Medical Express Clinic.
“It’s usually as a result of medication or an interaction between medicines.”
Serotonin is an important chemical messenger involved in a range of functions, including mood, sleep and digestion.
Certain medications can increase serotonin activity. In some circumstances, taking combinations of medicines that affect serotonin can cause levels of serotonin activity to become excessive.
“Serotonin syndrome can cause symptoms including agitation or confusion, sweating, a fast heart rate, shaking and muscle twitching, and in severe cases can become life-threatening,” says Dr Shoka.
“Serotonin syndrome can be a serious condition if undetected and untreated.”
What are the warning signs?
My experience taught me that serotonin syndrome isn’t necessarily something you will recognise immediately.
According to Dr Shoka, early symptoms can include:
- Tremors
- Feeling very fidgety or agitated
- Sweating
- Dilated pupils
- Mild jerky movements or clonus
As the condition becomes more severe, symptoms can include high body temperature, muscle rigidity and delirium.
Severe cases can involve seizures and other potentially life-threatening complications.
This is why recognising a sudden change in how you feel after starting or changing medication is important.
How common is serotonin syndrome?
The good news is that serotonin syndrome is uncommon, and most people who take SSRIs will not develop it.
Dr Shoka estimates that it occurs in around 0.1–2% of people prescribed serotonin reuptake inhibitors, although estimates vary depending on the population studied and how cases are defined.
The risk can increase when medications that affect serotonin are combined or when drug interactions are overlooked.
“Serotonin reuptake inhibitors should be prescribed by a medically qualified person under regular monitoring and supervision,” Dr Shoka says.
“The detection of early warning signs is crucial for preventing it. Avoiding drug overload and managing drug-to-drug interaction is very important.”
In my case, this was the part that particularly resonated.
What women taking antidepressants should know
Millions of people take antidepressants and other medications that affect serotonin, and they can be extremely important in treating conditions such as depression and anxiety.
My experience isn’t intended to frighten anyone away from medication. For many people, antidepressants can be an important part of managing their mental health.
But it has made me much more conscious of asking questions whenever a medication is started, stopped or changed.
If you are prescribed a new medication, make sure your doctor or pharmacist knows about everything else you take, including prescription medicines, over-the-counter treatments and supplements.
Don’t stop prescribed medication without medical advice, unless you have been specifically instructed to do so. If you develop concerning symptoms after starting or changing medication, seek urgent medical advice.
The lesson I took away
Before experiencing serotonin syndrome, I had never realised that taking medications that affect the same chemical system could potentially trigger such a dramatic reaction.
The sudden confusion, uncontrollable crying, physical movements and overwhelming sense of dread were terrifying precisely because I didn’t understand what was happening.
I was lucky that my GP recognised the warning signs quickly.
My experience is also a reminder that knowing the names of your medications isn’t enough. Understanding what they do, checking potential interactions and telling healthcare professionals about everything you’re taking can all help reduce the risk of medication-related problems.
Serotonin syndrome does not routinely happen to people taking SSRIs. But if you’re taking medication that affects serotonin, knowing the warning signs could help you recognise when something isn’t right – and know when to seek help.
