Isoniazid Drug Side Effects Lead to Fatal Liver Failure

A hospital consultant has apologised to the family of Dymphna Dykes, a 68-year-old woman who died after suffering toxic liver failure caused by the Isoniazid drug side effects. The drug had been prescribed to treat her latent tuberculosis (TB).

At an inquest held at Dublin District Coroner’s Court, consultant Professor Séamas Donnelly expressed deep regret, saying:

“Myself, the GP, and the system let the family down.”

Treatment for Latent TB Turns Fatal

In August 2020, Ms. Dykes was prescribed a six-month course of Isoniazid, the standard first-line medication used to treat latent tuberculosis infections. Isoniazid is effective but known to occasionally cause liver toxicity, a risk that affects about 1% of patients.
To monitor for this risk, monthly liver function tests were recommended. However, evidence presented to the inquest revealed that these tests were never carried out during her treatment.

Missed Monitoring and Communication Gaps

Professor Donnelly told the court that he had written to Ms. Dykes’s general practitioner, Dr. Siobhán Kierans, in August 2020 to confirm whether her practice would handle the monthly blood tests or if they should be arranged at the hospital.
He said he never received a reply from the GP but had assumed that the tests were being done because there was no indication otherwise. Unfortunately, that assumption proved fatal.
Dr. Kierans admitted during her evidence that she could not recall fully reading the consultant’s letter and was unaware of the need for regular monitoring while Ms. Dykes was taking Isoniazid. The GP, who is no longer in practice, described her oversight as something that had “gone under the radar” and acknowledged, “It was a bit stupid of me.”
She also agreed that there was a lack of systems in her practice to ensure proper follow-up on such important communications.

Rapid Decline After Treatment Ended

Ms. Dykes completed her six-month course of Isoniazid in early February 2021. Two weeks later, she became seriously ill and was admitted to Tallaght University Hospital (TUH) with signs of acute liver failure.
Consultant hepatologist Dr. Niall Breslin testified that the liver damage likely began in the first few months of treatment. Despite intensive care, Ms. Dykes’s condition worsened, and she was transferred to St Vincent’s University Hospital, where doctors determined she was not suitable for an urgent liver transplant.
She sadly passed away on March 26, 2021, from multi-organ failure due to acute liver failure.

Postmortem Findings: Severe Liver Damage

Pathologist Dr. Niamh Nolan reported that Ms. Dykes’s liver had shrunk dramatically, weighing only 390 grams compared with a normal average of about 1,500 grams. The findings confirmed extensive tissue loss caused by the toxic effects of Isoniazid.
While such a reaction is rare, Dr. Nolan emphasised that it is a well-recognised side effect and highlights why routine monitoring of liver function is critical for anyone on this medication.

Hospital Changes After the Tragedy

Following Ms. Dykes’s death, Prof. Donnelly said Tallaght University Hospital has introduced a more proactive follow-up process. Now, if a GP does not respond to his letters regarding monitoring tests, he personally follows up to confirm that testing arrangements are in place.
However, he admitted that even with new measures, “it’s not a perfect system.”
He also accepted that he had missed an opportunity to clarify whether Ms. Dykes was having the correct liver tests when he saw her in October 2020, a few weeks into her treatment.

Medical Misadventure

Coroner Cróna Gallagher recorded a verdict of medical misadventure, noting that Ms. Dykes’s death was an unintended consequence of medical treatment. She stated that the required liver monitoring tests were not carried out during the six-month course of Isoniazid.
While the verdict is considered neutral, meaning there was no intent or gross negligence, it acknowledges that failures occurred at multiple levels of care.

Family’s Response and Hope for Change

After the inquest, solicitor Aidan Flahavan, representing the Dykes family, said they welcomed the verdict and hoped that healthcare providers would learn important lessons from this case.
Professor Donnelly again apologised directly to the family, expressing his sorrow to Ms. Dykes’s husband, Freddie, and their daughters, Kerena and Aiveen.

Conclusion

The case of Dymphna Dykes highlights the importance of strict monitoring for Isoniazid drug side effects, particularly liver toxicity. Regular liver function tests are essential to detect early signs of liver injury, which can often be managed if identified promptly.

For both doctors and patients, clear communication and follow-up systems are vital to ensure safe and effective treatment of latent tuberculosis.

Source: Inputs from various media Sources

Priya Bairagi

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I’m a pharmacist with a strong background in health sciences. I hold a BSc from Delhi University and a pharmacy degree from PDM University. I write articles and daily health news while interviewing doctors to bring you the latest insights. In my free time, you’ll find me at the gym or lost in a sci-fi novel.