The commonest side-effects of saquinavir (Invirase) are diarrhoea, abdominal discomfort, headache and nausea. These are most likely to occur during the early weeks of treatment. Medicines to control nausea, diarrhoea and headache can be prescribed before starting saquinavir. The risk of side-effects is increased if saquinavir is combined with ritonavir.

As a class, protease inhibitors have been associated with a syndrome of fat and metabolic irregularities. This syndrome includes body fat redistribution, high fat levels in the blood, diabetes, increased levels of blood sugar and increased bleeding in haemophiliacs. For more details, see Body fat and metabolic changes whilst on treatment.

Saquinavir is not linked to liver toxicity.