Hello. 4 days ago I started taking Hydroxycut Onix. I accidentally drank a cup of coffee after that. I was at work and began feeling my heart rate rise, along with my blood pressure and could barely breathe. I went to the hospital. The first time the doctor performed a blood test and also checked my blood pressure which was a little high... She told me everything was within parameters, however, that same day I started feeling palpitations again and shortness of breath and went back to the hospital where they performed an electro cardiogram. The doctor also told me that I had not heart conditions, and that I should just rest and let the effects of the caffeine pass. I ve never experienced issues with caffeine before, nor felt this tired/shortness of breath before ( If I walk a short distance, I get agitated). I went to a clinic where they checked my electrolytes and magnesium and potassium levels, as well as my hemoglobin and everything checked within the normal range! This happened on Monday 02-8-16... It is now 02-12-16 and I m still feeling like I can t walk for a short time because otherwise I feel that my chest becomes heavy and I have trouble breathing. Ever since that happened, I have not taken any caffeine again in any form and will definitely not ever take it again. Please help as the doctors are telling me that I m ok, but I do not feel that this side effect should last this long!!! What can it be??