Hi All drugs have side effects but most common with karvezide which contains irbesartan and hydrochlorthiazide.Irbesartan may cause headach,ringing in ears,cough taste disturbance,indigestion,pain in joints,abnormal liver function,and kidney function,increased level of potassium in blood,rash and swelling of face,lips,tounge etc side effects of hydrochlorthiazide in karvezide may cause loss of appetite,stomach cramps,jaundice,sleep disorders,decrease in platelet count,tiredness dizziness,photo sensitivity side effects of perindopil may be headache,dizziness,sleep disorder,fever,depression,cough,chest pain,abnormal ECG etc Side effects list is long but only a few people get some of these side effectc Hope this answers your query