The most common side effects with Epivir (seen in between 1 and 10 patients in 100) are diarrhoea, nausea (feeling sick), vomiting, headache, insomnia (difficulty sleeping), cough, nasal symptoms, rash, muscle disorders, arthralgia (joint pain), alopecia (hair loss), fever, abdominal (tummy) pain or cramps, malaise (feeling unwell) and fatigue (tiredness).