Before the decision to buy Calan is made, a history of low blood pressure, AV blocks, or a recent heart attack needs to be discussed with your local physician. This medication can cause impaired judgement, so patients are cautioned while driving or performing tasks that require you to be awake and alert. If serious conditions such as kidney disease, liver disease, or muscle disorders are in the medical history, inform your personal physician. It is unknown if this medication is harmful during pregnancy, so consult your local physician before starting a generic Calan treatment if you are pregnant or plan to become pregnant. Severe reactions have been reported in patients who are taking prescription to treat asthma in conjunction with this medication.