Question: Hi I recently returned from a holiday to china and was prescribed doxycycline tablets to take before and after trip. I commenced taking them on 12/10/14 and am still taking them. I suffer from Atrial Fibrillation for which I am prescribed metoprolol 50mm per day. Up to this trip I only suffered mild infrequent AF episodes usually at night and whilst at rest. I am a lawn contractor and for the past few days I have had irregular heart beats whilst mowing, no chest pain for shortness of breath. I have my two yearly stress test with my cardiologist tomorrow. Could the doxycycline be causing these irregular beats which commence shortly after I put some stress on the heart to perform.? XXXXXXX

Hi Dr XXXXXXX - thank you for your reply. Today I saw my cardiologist and my stress test was positive with no signs of any heart muscle or vascular problems. Heart function was normal for a person of my age and condition. The cardiologist did however share my concerns that docycycline was a contributing factor. The reason I contacted you was after researching the possible side effects of the drug which stated that irregular heart rhythms was possible. I have stopped taking the drug and have noticed a significant improvement with few or no irregular rhythms. These rhythms were identified as ectopic and benign during the stress test on the ECG. consequently I am disappointed in your response and information because it failed to clearly identify possible underlying causes. Your response was very general and provided no solution other than to obtain further medical assistance. I believe that under these circumstances I should receive a full refund of my fee.