The most common side effects with Isentress (seen in between 1 and 10 patients in 100) are insomnia (difficulty sleeping), dizziness, headache, abdominal distension (bloating), abdominal (tummy) pain, constipation, diarrhoea, flatulence (gas), nausea (feeling sick), vomiting, hyperhidrosis (excessive sweating), night sweats, pruritus (itching), rash, arthralgia (joint pain), asthenia (weakness), fatigue (tiredness) and increased blood levels of liver enzymes (alanine aminotransferase and aspartate aminotransferase), triglycerides (a type of fat), creatinine kinase (an enzyme found in muscles) and lipase (an enzyme found in the pancreas).