The DrugCard platform is known for its ability to detect adverse drug reactions (ADRs) in multilingual literature. One powerful feature is its instant English translation – you can analyse Romanian, Serbian, or any other language article in seconds. But what happens when the adverse reaction itself speaks a different language? This is not science fiction. It’s a rare neurological condition called foreign language syndrome, and it’s more than just a linguistic mystery – it may be a warning sign of serious neurotoxicity.

Let’s dive into a rare and intriguing case that blurs the lines between pharmacovigilance, psychiatry, and neurology.

What Is Foreign Language Syndrome?

Foreign language syndrome (FLS) is a rare neurological phenomenon in which a person spontaneously begins speaking a language other than their native tongue. Unlike foreign accent syndrome, where patients retain their native language but speak it with an unfamiliar accent, FLS involves a complete switch in grammar, vocabulary, and syntax to a second language.

Most documented cases occur following general anesthesia or neurological trauma and are often short-lived. The patient usually has some prior exposure to the language, such as school lessons or passive media consumption, but has never used it actively or fluently.

Despite the dramatic presentation, FLS is usually self-limited and resolves without long-term neurological damage. However, its presence often signals underlying brain dysfunction, making it a matter of interest for pharmacovigilance.

A Case That Spoke for Itself

A 34-year-old man with schizoaffective disorder was hospitalised for a depressive episode. On day four, he received 50 mg of intramuscular chlorpromazine to manage persistent insomnia.

By the next morning, his condition had deteriorated. He was pale, sweaty, non-verbal, and exhibited muscle rigidity – classic signs of neuroleptic malignant syndrome (NMS). Then came the extraordinary moment: he suddenly began speaking fluent English, asking:

“Where am I? What hospital is this? Why am I here? What’s wrong with me?”

His speech was coherent, emotionally expressive, and grammatically correct. Yet this man had never spoken English in real life. His exposure was limited to school textbooks and TV cartoons. He had never travelled abroad or engaged in English conversations.

The entire episode lasted about five minutes. Patient then fell silent again and resumed his confused, non-communicative state.

Pharmacovigilance Implications of Foreign Language Syndrome

This case illustrates how altered mental states associated with severe ADRs – like NMS – can produce bizarre neurological phenomena. Foreign language syndrome is not just a linguistic oddity; it can be a marker of neurotoxicity or profound brain dysfunction.

For pharmacovigilance professionals, this underlines the need to:

Document and report unusual behavioral or speech changes.

Be alert to neurological symptoms even when not classically listed.

Consider the cultural and linguistic context when assessing ADRs.

There’s a strange poetry in this story. While DrugCard automatically translates medical literature to aid safety teams, the patient in this case did the same – his brain, under chemical assault, switched languages for reasons still not fully understood.

It’s a vivid reminder that drug safety is never just pharmacokinetics and lab values. It’s also about human behavior, memory, emotion, and sometimes even language.

Conclusion

Foreign language syndrome is sporadic, but its occurrence during a life-threatening adverse reaction like NMS should not be ignored.

For pharmacovigilance professionals, this case is a compelling example of how the unexpected can provide critical insight into drug safety. The human brain reacts in mysterious ways – and sometimes, the language of safety signals is far from familiar.

In this case, DrugCard helped uncover the story. And in an even stranger twist, the patient helped translate it.