According to the US Food and Drug Administration’s (FDA) warning issued Monday, HIV patients taking a Bristol-Myers Squibb drug could be at risk of a rare, but fatal liver disorder.

Since 1991, when Videx was approved, 42 reports of the order have been received, with four patients who developed the problem, dying from bleeding or liver failure, known as non-cirrhotic portal hypertension.

In this problem, the blood flows dangerously slow through the liver, causing the thin veins in the esophagus to swell, and being thin, these veins can burst, resulting in potentially fatal bleeding.

The only reason the drug is still on the market, is because FDA says its benefits far outweigh its risks. The drug prevents HIV from multiplying and is used in combination with other virus-fighting drugs in both adults and children.

Warnings have been added to the drug’s label regarding signs and symptoms of the liver disorder, and patients ‘should be monitored for early signs of portal hypertension during routine medical visits.’

As well, Bristol Myers Squibb based in New York has been asked by FDA to develop a medication guide for patients detailing Videx’s risks.