I have been using Seretide (Advair) for around 6 months and like a lot of you thought the drug was wonderful with how it was controlling my Asthma. I am usually a fit and well person but over the last couple of weeks have been feeling so tired and lethargic, even the smallest task wiping me out. I thought nothing of it really, just stresses and strains of modern life. Then I started to get frequent palpitations and every time I fell asleep my heart would miss a beat and I would wake up. This would last a couple of hours and obviously over a matter of weeks I was getting more and more exhausted. I talked to my Doctor and she said that Seretide could cause abnormal heart rythyms, and along with the frequent oral thrush and dry mouth I have decided to give up on Seretide, hope it hasn't done any long term damage and resolve to using my salbutamol more often. It was great to find this site and discover that these side effects are not uncommon amongst others.