Ribavirin antiviral drug, molecular model. Ribavirin is an antiviral medication for several haemorrhagic fevers and for hepatitis C. In vivo, ribavirin is converted to an analogue of guanosine that can inhibit the biosynthesis of viral RNA (ribonucleic acid). Atom colour codes: carbon is black; hydrogen is white; nitrogen is blue; oxygen is red; phosphorus is orange.